pi|iti|i;N!:;;:' 
 
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CORNELL 
 
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 LIBRARY 
 
 BOUGHT WITH THE INCOME 
 OF THE SAGE ENDOWMENT 
 FUND GIVEN IN 1891 BY 
 
 HENRY WILLIAMS SAGE 
 
The original of tliis book is in 
 tine Cornell University Library. 
 
 There are no known copyright restrictions in 
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 http://www.archive.org/details/cu31924030584605 
 
Cornell University Library 
 
 LB1131.T31 S6 
 
 The Stanford revision and extension of t 
 
 olin 
 
 3 1924 030 584 605 
 
THE STANFORD REVISION AND EXTENSION 
 
 OF THE BINET-SIMON SCALE FOR 
 
 MEASURING INTELLIGENCE 
 
jE&uraltottal j^aarl^ologg jMonograplfa 
 
 No. 18 
 
 THE STANFORD REVISION AND EXTENSION 
 
 OF THE BINET-SIMON SCALE FOR 
 
 MEASURING INTELLIGENCE 
 
 Bt 
 
 Lewis M. Terman, Grace Lyman, Geobge Ordahl, 
 Louise Ellison Ordahl, Neva Galbreath 
 
 AND WiLFORD TaLBERT 
 Abbisted bt 
 
 Herbert E. Knollin, J. H. Williams, H. G. Childs, Helen 
 
 Trost, Richard Zeidlbr, Charles Waddle 
 
 AND Irene Cuneo 
 
 BALTIMORE 
 
 WARWICK & YORK, Inc. 
 1917 
 
1131 
 
 T31 
 
 S4> 
 
 C^l5TSli|ri917. 
 
 By 
 
 Wabwiok & YoBK, Inc. 
 
 m 
 

 Dedicated 
 
 by 
 Lewis M. Terman 
 
 to 
 
 Those whose loyal cooperation 
 
 made the study possible 
 
EDITOR'S PREFACE 
 
 The labors of Professor Terman and his co-workers 
 at Stanford University in the critical examination and 
 improvement of the Binet-Simon Scale for Measuring 
 Intelligence are so well and so favorably known by 
 psychologists and by the many users of the method 
 that no words of editorial introduction are needed to 
 call attention to the importance of the present mono- 
 graph. 
 
 The results of these labors are embodied in the Stan- 
 ford Revision of the Binet-Simon Scale. A general 
 guide for the appUcation of this Revision has been 
 published elsewhere. In the present monograph, how- 
 ever, the reader is taken "behind the scenes," is shown 
 the precise methods by which the Revision was made, 
 the actual data on which it was based. There is intro- 
 duced also an instructive discussion of a nmnber of 
 very sahent questions: What is the nature of intelli- 
 gence? How is intelUgence distributed? What sex 
 differences exist in intelUgence? What is the relation 
 between intelligence and social status? Between 
 intelligence and school success? Is the intelUgence 
 quotient a vaUd measure? How shall the vaUdity of 
 any single test in an intelUgence scale be determined? 
 What principles should govern the assembling of 
 tests into a system, or scale? These questions have 
 more than a merely technical interest: they bear in 
 many ways upon practical problems of school instruc- 
 tion and administration. The monograph should do 
 much to stimulate and to clarify thinking, both in 
 psychological and in pedagogical circles. 
 
 G. M. W. 
 
12 STANFORD REVISION OF BINET-SIMON SCALE 
 
 by not going back far enough. Errors of this sort 
 doubtless about balance in the long run, and so do not 
 affect appreciably the distribution of mental ages. 
 They do affect, however, the statistical treatment 
 of the results for individual tests, and as a rule we 
 have given the per cents passing a test only for those 
 ages at which all the children were given the test. 
 
 6. Much attention was given to securing uniformity 
 of procedure. A half-year was devoted to training 
 the examiners and another half-year to the supervi- 
 sion of the testing.'* In the further interests of uni- 
 formity all the records were scored by one person 
 (Terman). 
 
 In working out a revision of the scale the guiding 
 principle was to secure an arrangement of the tests 
 and a standard of scoring which would cause the median 
 mental age of the children of each age-group to coincide 
 with the median chronological age. If the median 
 mental age at any point in the scale was too high or 
 too low, it was only necessary to change the location 
 of certain of the tests, or to change the standard of 
 scoring, until an order of arrangement and a standard 
 of passing were found which would throw the median 
 mental age where it belonged. We had already be- 
 come convinced that no satisfactory revision of the 
 Binet scale was possible on any theoretical consider- 
 ( ations as to the percent of passes which an individual 
 test ought to show in a given year in order to be con- 
 sidered standard for that year, although such a plan 
 might be feasible with a scale differently founded. 
 
 ^ This statement does not apply, however, to Professor and Mrs. 
 Ordahl, who had to rely on a 20-page guide, supplemented by a few 
 demonstration tests and such further direction as could be given by 
 correspondence. Mr. Talbert and Miss Cuneo had also somewhat 
 less specific training for the tests than had the others, though both had 
 taken a half-year course in cUnioal psychology. 
 
THE STANFOKD KE VISION AND ITS HISTORY 13 
 
 As was to be expected, the first draft of the revision 
 did not prove satisfactory. The scale was still too 
 hard at some points and too easy at others. Three 
 successive revisions were necessary, involving three 
 separate scorings of the data and as many tabulations 
 of the mental ages, before the desired degree of accur- 
 acy was secured. 
 
 As finally left, the scale gives a median intelligence 
 quotient closely approximating 100 for our non-se- 
 lected children of each age. The revision contains 
 six regular tests and from one to three alternative 
 tests in each year from 3 to 10, eight tests at year 12, 
 six at 14, and six in each of two higher groups which 
 are named, in order, "average adult" and "superior 
 adult." 
 
 The tests in the two highest groups were standardized 
 chiefly on the basis of results from 400 adults. The 
 extension of the scale in the upper range is such that 
 ordinarily intelligent adults, httle educated, test near 
 to what is called the "average adult" level. Adults 
 whose intelligence is known from other sources to be 
 superior are found to test well up to the "superior 
 adult" level, whether they are well educated or prac- 
 tically unschooled. Of 30 uneducated business men, 
 15 tested at "average adult" (15-17), 8 at "superior 
 adult" (17-19), 6 at "inferior adult" (14-15) and 1 
 at 13. Of 32 high-school students who were 16 years 
 of age or older, 22 tested at "average adult," 5 at 
 "superior adult," 5 at "inferior adult." 
 
 The trial arrangement of tests included, in addition 
 to those of the Binet 1908 and 1911 series, 31 addi- 
 tional tests, as follows: Kuhlmann's test of discrimin- 
 ation of forms, two new tests of comprehension (Terman), 
 four tests of repeating digits in reversed order (suggested 
 by Bobertag), repeating 8 digits, test of ability to tie 
 a bow-knot (Termanl. two tests of finding similarities 
 
14 STANFOED KEVISION OF BINET-SIMON SCALE 
 
 (Terman), six vocabulary tests (Terman and Childs), 
 two form-board tests (Healy and Femald), the Healy- 
 Femald code test, two tests of fable interpretation (Ter- 
 man and Childs) , two " ball and field " tests (Terman and 
 Childs), an "induction" test (Terman), a test of arith- 
 metical reasoning (selected from Bonser's series), an 
 "ingenuity" test (Terman), a test of "comprehension 
 of physical relations" (suggested in part by Meumann), 
 a test of observation (drawing an apple with pencil 
 through it, suggested by an experiment of Professor 
 Earl Barnes), and the "problem of enclosed boxes" 
 (Terman). The test of observation proved too un- 
 satisfactory to be included in the revision, as was true 
 also of one of the Healy-Fernald form boards and 
 Binet's "suggestion" and "reversed triangle" tests. 
 Counting both regular and alternative tests, the re- 
 vision contains 90 tests, as contrasted with 54 in the 
 Binet 1911 series. 
 
 As far as possible, the original Binet tests have been 
 retained in the form in which they were used by their 
 author, although in a number of cases it has seemed 
 advisable to introduce alterations either in procedure 
 or scoring. In preparing the directions, special at- 
 tention has been devoted to the difficulties encountered 
 by inexperienced examiners in giving and scoring the 
 tests. 5 
 
 While it is not claimed that the revision here offered 
 is satisfactory in every respect,- the authors beUeve 
 that it possesses a number of distinct advantages over 
 other versions of the Binet scale. Among these ad- 
 vantages are the following: 
 
 = An extended guide for the giving and scoring of the individual 
 tests and for the interpretation of test results has been published in a 
 separate volume, The Measurement of Intelligence (Houghton Mifflin 
 Co., 1916). With the latter is furnished all the necessary material 
 for the use of the Stanford Revision. 
 
THE STANFORD REVISION AND ITS HISTORY 15 
 
 1. Correction of the too-great ease of the original 
 scale at its lower end and its too-great difl&culty at 
 the upper end. This correction should have the im- 
 portant result of tending to prevent the overlooking 
 of borderline cases of deficiency among young children 
 and the overestimation of deficiency among adults of 
 somewhat inferior or borderline intelligence.' 
 
 2. The revision not only contains a much larger 
 number of tests than any other series, but also brings 
 into operation a much greater variety of mental fimc- 
 tions. This is especially true for the upper part of 
 the scale. 
 
 3. It is believed that the detailed directions set forth 
 in the companion volume for giving and scoring the 
 tests should tend materially to promote uniformity of 
 procedure. 
 
 The following copy of the forms used in applying 
 the tests wiU serve to indicate their nature. 
 
 YEAB, III. (6 tests, 2 months each.) 
 
 1. Points to parts of body. (3 of 4.) 
 
 Nose Eyes Mouth Hair 
 
 2. Names familiar objects. (3 of 5.) 
 
 Key Penny Closed kiiife Watch Pencil 
 
 3. Pictures, enumeration or better. (At least 3 objects in one picture. 
 
 "Tell me everything you can see in this picture.") 
 
 a. Dutch Home 
 
 6. Canoe 
 
 c. Post Office 
 
 4. Gives sex. (Note form of question.) 
 
 6. Gives last name 
 
 6. Repeats 6-7 syllables. (1 of 3.) 
 
 a. "1 have a Uttle dog." 
 6. "The dog runs after the cat." 
 c. "In summer the sun is hot." 
 Al. Repeats 3 digits. (1 of 3. Order correct. Read 1 per second.) 
 6-4-1 3-5-2 8-3-7 
 
 YEAR IV. (6 tests, 2 months each.) 
 
 1. Compares hnes. (3 of 3, or 5 of 6.) 1 2 3 
 
 2. Discrimination of forms. (Kuhhnann. 7 of 10.) 
 
 Circle Square Triangle Other errors 
 
 » For a fuller discussion, see L. M. Terman, Some problems related 
 to the detection of border-hne cases of mental deficiency, J. of Psycho- 
 Asthenics, Sept. and Dec, 1915. 
 
16 STANFOKD REVISION OF BINET-SIMON SCALE 
 
 3. Counts 4 pennies. (No error.) 
 
 4. Copies square. (Pencil. 1 of 3.) 1 2 3 
 
 5. Comprehension, 1st degree. (2 of 3.) "What must you do: 
 
 a. "When you are sleepy? 
 
 b. "When you are cold? 
 
 c. "When you are himgry?" 
 
 6. Repeats 4 digits. (1 of 3. Order correct. Read 1 per second.) 
 
 4^7-3-9 2-8-6-4 7-2-6-1 
 
 Al. Repeats 12-13 syllables. (1 of 3 absolutely correct, or 2 with 1 
 error each.) 
 o. "The boy's name is John. He is a very good boy." 
 6. "When the train passes you will hear the whistle blow."- 
 c. "We are going to have a good time in the country." 
 
 YEAR V. (6 tests, 2 months each.) 
 
 1. Comparison of weights. (2 of 3.) 
 
 3-15 15-3 3-15 
 
 2. Colors. (No error.) 
 
 Red Yellow Blue Green 
 
 3. Aesthetic comparison. (No error.) 
 
 Upper pair Middle Lower 
 
 4. Definitions, use or better. (4 of 6.) 
 
 Chair Doll 
 
 Horse Pencil 
 
 Fork Table 
 
 5. Patience, or divided rectangle. (2 of 3 trials. 1 minute each.) 
 
 1 Time 
 
 2 Time 
 
 3 Time 
 
 6. Three commissions. (No error. Order correct.) 
 
 Puts key on chair Brings box Shuts door 
 
 Al. Age 
 
 YEAR VI. (6 tests, 2 months each.) 
 
 1. Right and left. (3 of 3, or 5 of 6.) 
 
 R. hand L. ear R. eye 
 
 2. Mutilated pictures. (3 of 4.) 
 
 Eye Mouth Nose Arms 
 
 3. Counts 13 pennies. (1 of 2 trials, without error.) 
 
 4. Comprehension, 2d degree. (2 of 3.) " What's the thing to do : 
 
 o. "If it is raining when you start to school? 
 
 b. "If you find that your house is on fire? 
 
 c. "If you are going some place and miss your car?" 
 
 5. Coins. (3 of 4. Present in order given below.) 
 
 Nickel Penny Quarter Dime 
 
 6. Repeats 16-18 syllables. (1 of 3 absolutely correct, or 2 with 1 error 
 
 each.) 
 o. "We are having a fine time. We foimd a little mouse in the 
 
 trap." 
 6. "Walter had a fine time on his vacation. He went fishing every 
 
 day." 
 c. "We will go out for a long walk. Please give me my pretty 
 
 straw hat." 
 Al. Morning or afternoon, __(NQteJorm of question.) 
 
THE STANFOED REVISION AND ITS HISTORY 17 
 
 YEAR VII. (6 tests, 2 months each.) 
 
 1. Fingers. (No error.) R L Both 
 
 2. Pictuies, description or better. (Over half of performance descrip- 
 
 tion. "Tell me what this picture is about?" "What is this 
 a picture of? ") 
 o. Dutch Home 
 
 b. Canoe 
 
 c. Post Office 
 
 3. Repeats 5 digits. (1 of 3. Order correct. Read 1 per second.) 
 
 3-1-7-5-9 4r-2-8-3-5 9-8-1-7-6 
 
 4. Ties bow knot. (Model shown. 1 minute. "Single" bow half 
 
 credit.) 
 Time Method 
 
 5. Gives differences. (2 of 3.) 
 
 a. Fly and butterfly 
 
 b. Stone and egg 
 
 c. Wood and glass 
 
 6. Copies diamond. (Pen. 2 of 3.) a b c 
 
 Al. 1. Names days of week. (Order correct. 2 of 3 checks correct.) 
 
 Mon., Tues., Wed., Thurs., Fri., Sat., Sun. 
 Al. 2. Repeats 3 digits backwards. (1 of 3. Read 1 per second.) 
 2-8-3 4r-2-7 9-5-8 
 
 YEAR VIII. (6 tests, 2 months each.) 
 1. Ball and field. (Inferior plan or better.). 
 
 2. Counts 20-0. (40 seconds. 1 error allowed.) Time. . . .Errors. . . . 
 
 3. Comprehension, 3rd degree. (2 of 3.) "What's the thing for you 
 
 to do: 
 a. "When you have broken something which belongs to someone 
 
 else? 
 
 6. "When you are on your way to school and notice that you are 
 
 in danger of being tardy? 
 
 c. "If a playmate hits you without meaning to do it?" 
 
 4. Gives similarities, two things. (2 of 4. "In what way are wood 
 
 and coal alike?" etc. Any real likeness is plus.) 
 
 a. Wood and coal 
 
 6. Apple and peach 
 
 c. Iron and silver 
 
 d. Ship and automobile 
 
 5. Definitions superior to use. (2 of 4. "Thing" as genus counts • 
 
 plus.) 
 o. Balloon 
 
 b. Tiger 
 
 c. Football 
 
 d. Soldier. 
 
 6. Vocabulary, 20 words. Score Total Vocab 
 
 Al. 1. Six coins. (No error. Give in order indicated.) 
 
 .05 01 25 10 1.00 50 
 
 Al. 2. Dictation. ("See the httle boy." Easily legible. Pen, 1 
 minute.) 
 Time Score by Ayres scale 
 
18 STANFORD REVISION OF BINET-SIMON SCALE 
 
 YEAR IX. (6 tests, 2 months each.) 
 
 1. Date. (Allow error of 3 days in c, no error in a, 6, or d.) 
 
 a. Day of week 6. month c. day of m d. year 
 
 2. Weights. (3, 6, 9, 12, 15. Procedure not illustrated. 2 of 3 
 
 correct.) 
 
 a Method 
 
 b Method 
 
 c Method 
 
 3. Makes change. (2 of 3. No coins, paper, or pencil.) 
 
 1(^4 15-12 25-4 
 
 4. Repeats 4 digits backwards. (1 of 3. Read 1 per second.) 
 
 6-5-2-8 4^9-3-7 8-6-2-9 
 
 5. Three words. (2 of 3. Oral. 1 sentence or not over 2 codrdinate 
 
 clauses.) 
 
 a. Boy, river, ball 
 
 6. Work, money, men 
 
 c. Desert, rivers, lakes 
 
 6. Rhymes. (3 rhymes for each word. 1 minute for each part. 
 
 Illustrate with hat, rat, cat.) 
 
 a. Day Time 
 
 6. Mill Time 
 
 c. Spring Time 
 
 Al. 1. Months. (15 seconds and 1 error in naming. 2 checks of 3 
 correct.) 
 Jan., Feb., Mch., Apr., May, June, July, Aug., Sept., Oct., Nov., 
 Dec. 
 AI. 2. Stamps, gives total value. (2d trial if individual values are 
 known.) 
 
 YEAR X. (6 tests, 2 months each.) 
 
 1. Vocabulary, 30 words. Score Total Vocab 
 
 2. Absurdities. (4 of 5. Warn. Spontaneous correction allowed.) 
 
 a. "A man said: 'I know a road from my house to the city which 
 is down hiU all the way to the city and down hill all the way 
 backihome.'" 
 
 6. "An engineer said that the more cars he had on his train the 
 faster he could go." 
 
 c. "Yesterday the police found the body of a girl cut into 18 
 pieces. They beheve that she killed herself." 
 
 d. "There was a railroad accident yesterday, but it was not very 
 serious. Only 48 people were killed." 
 
 e. "A bicycle rider, being thrown from his bicycle in an accident, 
 struck his head against a stone and was instantly killed. They 
 picked him up and carried him to the hospital, and they do not 
 think he will get well again." 
 
 3. Designs. (1 correct, 1 half correct. Expose 10 seconds.) a. . .b. . . 
 
 4. Reading and report. (8 memories. 35 seconds and 2 mistakes in 
 
 reading.) 
 
 Memories Time for reading Mistakes 
 
 New York. | September 5th. | — A fire | last night | burned | three 
 houses I near the center | of the city. | It took some time | to put it out. | 
 
THE STANFORD REVISION AND ITS HISTORY 19 
 
 The loss I was fifty thousand dollars, | and seventeen families | lost 
 their homes. ] In saving I a girl | who was asleep | in bed, | a fireman | 
 was burned | on the hands. 
 
 5. Comprehension, 4th degree. (2 of 3. Question may be repeated.) 
 
 a. "What ought you to say when someone asks your opinion about 
 a person you don't know very weU?" 
 
 6. "What ought you to do before undertaking (beginning) some- 
 thing very important?" 
 
 c. "Why should we judge a person more by his actions than by his 
 words?" 
 
 6. 60 words. (Score half-minutes separately. Illustrate with clouds, 
 
 dog, chair, happy.) 1 2 3 4 5 6 
 
 Method 
 
 Al. 1. Repeats 6 digits. (1 of 2. Order correct. Read 1 per sec- 
 ond.) 
 
 3-7-4-S-5-9 5-2-1-7-^W 
 
 Al. 2. Repeats 20-22 syllables. (1 of 3 correct, or 2 with 1 error 
 each.) 
 
 a. "The apple tree makes a cool pleasant shade on the ground 
 where the children are playing." 
 
 6. "It is nearly half-past one o'clock; the house is very quiet and 
 the cat has gone to sleep." 
 
 c. "In simmier the days are very warm and fine; in winter it 
 snows and I am cold." 
 Al. 3. Form board. (Healy-Femald Puzzle A. 3 times in 5 min- 
 utes.) 
 
 Time: a 6 c Method 
 
 YEAR XII. (8 tests, 3 months each.) 
 
 1. Vocabulary, 40 words. Score Total Vocab 
 
 2. Abstract words. (3 of 5.) 
 
 a. Pity 
 
 6. Revenge 
 
 c. Charity 
 
 d. Envy 
 
 e. Justice 
 
 3. Ball and field. (Superior plan.) 
 
 4. Dissected sentences. (2 of 3. 1 minute each.) 
 
 a Time 
 
 6 Time 
 
 c Time 
 
 5. Fables. (Score 4, i. e., two correct or the equivalent ia haK credits.) 
 
 a. Hercules and wagoner 
 
 6. Maid and eggs 
 
 c. Fox and crow 
 
 d. Farmer and stork 
 
 e. Miller, son and donkey 
 
 6. Repeats 5 digits backwards. (1 of 3. Read 1 per second.) 
 
 3-1-8-7-9 6-9^r-8-2 5-2-9-6-1 
 
 7. Pictures, interpretation. (3 of 4. "Explain this picture.") 
 
 a. Dutch Home 
 
 6. Canoe 
 
20 STANFORD REVISION OF BINET-SIMON SCALE 
 
 c. Post Office 
 
 d. Colonial Home 
 
 Gives similarities, three things. (3 of 5. " In what way are — , - 
 
 — , alike?" Grade fairly closely.) 
 
 a. Snake, cow, sparrow 
 
 6. Book, teacher, newspaper 
 
 c. Wool, cotton, leather 
 
 d. Knife-blade, penny, piece of wire 
 
 e. Rose, potato, tree 
 
 -t 
 
 YEAR XIV. (6 tests, 4 months each.) 
 
 1. Vocabulary, 50 words. Score Total Vocab 
 
 2. Induction test. (Gets rale by 6th folding. Unfold after each 
 
 cutting.) 
 1 2 3 4 5 6 
 
 3. President and king. (Power.... accession.... tenure.... 2 of 3.) 
 
 o 
 
 6 
 
 c 
 
 4. Problems of fact. . (2 of 3. Query on o and 6.) 
 
 o. "A man who was walking in the woods near a city stopped 
 suddenly, very much frightened, and then ran to the nearest 
 poUceman, saying that he had just seen hanging from the limb 
 of a tree a a what?" 
 
 6. " My neighbor has been having queer visitors. First a doctor 
 came to his house, then a lawyer, then a minister (preacher or 
 priest). What do you think happened there?" 
 
 c. "An Indian who had come to town for the first time in his life 
 saw a white man riding along the street. As the white man rode 
 by the Indian said — 'The white man is lazy; he walks sitting 
 down.' What was the white man riding on that caused the 
 Indian to say 'he walks sitting down'?" 
 
 5. Arithmetical reasoning. (1 minute each. 2 of 3.) 
 
 a. If a man's salary is $20 a week and he spends $14 a week, how 
 long will it take him to save $300? 
 
 6. If 2 pencils cost 5 cents, how many pencils can you buy for 50 
 
 cents? 
 
 c. At 15 cents a yard, how much will 7 feet of cloth cost? 
 
 6. Clock. (2 of 3. Error must not exceed 3 or 4 minutes.) 
 
 6:22 Time required 
 
 8 :10 Time required 
 
 2 :46 Time required 
 
 Al. Repeats 7 digits. (1 of 2. Order correct. Read 1 ner second "i 
 3-1-&-3-4-3-9 9-7-2-8-4-7-5 ..... 
 
THE STANFORD REVISION AND ITS HISTORY 21 
 
 YEAR XVI, AVERAGE ADULT. (6 tests, 5 months each.) 
 
 1. Vocabulary, 65 words. Score Total Vocab 
 
 2. Interpretation of fables. (Score 8.) (First explain what a fable 
 
 is, and after reading each say, "What lesson does that teach 
 us?") 
 
 a. Hercules and wagoner 
 
 b. Maid and eggs 
 
 c. Fox and crow 
 
 d. Farmer and stork 
 
 e. Miller, son and donkey 
 
 3. Difference between abstract words. (3 real contrasts out of 4.) 
 
 a. Laziness and idleness 
 
 b. Evolution and revolution 
 
 c. Poverty and misery 
 
 d. Character and reputation 
 
 4. Problem of the enclosed boxes. (3 of 4.) One large box con- 
 
 taining: 
 
 a. 2 smaller, 1 inside of each 
 
 6. 2 smaller, 2 inside of each 
 
 c. 3 smaller, 3 inside of each 
 
 d. 4 smaller, 4 inside of each 
 
 5. Repeats 6 digits backwards. (1 of 3.) 
 
 4-7-1-9-5-2 5-8-3-2-9-4 7-5-2-6-3-8 
 
 6. Code, writes "Come quickly." (2 errors. Omission of dot counts 
 
 half error. Illustrate with "war," "trench," and "spy.") 
 
 Errors C-O-M-E Q-U-I-C-K-L-Y Time 
 
 Method 
 
 Al. 1. Repeats 28 syllables. (1 of 2 absolutely correct.) 
 
 a. Walter likes very much to go on visits to his grandmother, 
 
 because she always tells him many funny stories. 
 6. Yesterday I saw a pretty Uttle dog in the street. It had curly 
 brown hair, short legs, and a long tail. 
 Al. 2. Comprehension of physical relations. (2 of 3.) 
 — u,. Path of cannon ball 
 
 6. Weight of fish in water, 
 c. Hitting distant mark. . . 
 
 XVIII, SUPERIOR ADULT. (6 tests, 6 months each.) 
 1. Vocabulary, 75 words. Score Total Vocab. 
 
 2. Binet's paper cutting test. Draws folds and locates holes. (If 
 
 given, must come before XIV2.) 
 
 3. Repeats Sdigits. (lofS. Order correct. Read 1 per second.) 
 
 7l2-5-(5^-9-6. . . . 4-9-8-T5+3r 7-6-2. . . . 8-3-7-9-5-4^8-2. . . . 
 
 4. Repeats thought of passage heard. (1 of 2. E. reads each in about 
 
 }4 min.) "I am going to read you a little selection. Listen 
 carefully, and when I am through I will ask you to tell as much 
 of it as you can remember. Ready — " 
 
22 STANFORD EEVISION OF BINET-SIMON SCALE 
 
 a. "Tests such as we are now making are of value both for the 
 advancement of science and for the information of the person 
 who is tested. It is important for science to learn how people 
 differ and on what factors these differences depend. If we can 
 separate the influence of heredity from the influence of environ- 
 ment we may be able to apply our knowledge so as to guide 
 human development. We may thus in some cases correct 
 defects and develop abilities which we might otherwise neglect." 
 
 . "Many opinions have been given on the value of life. Some call 
 it good, other call it bad. It would be nearer correct to say 
 that it is mediocre, for on the one hand our happiness is never as 
 great as we should like, and on the other hand our misfortunes 
 are never as great as o\a enemies would wish for us. It is this 
 mediocrity of life which prevents it from being radically unjust." 
 
 6. Repeats 7 digits backwards. (1 of 3.) 
 
 4r-l-6-2-5-9-3 3-8-2-6-4-7-5 9-4-5-2-8-3-7 
 
 6. Ingenuity test. (2 of 3. 5 minutes each. If S fails on 1st, E 
 explains that one.) 
 o. "A mother sent her boy to the river to get seven pints of water. 
 She gave him a 3-pint vessel and a 5-pint vessel. Show me how 
 the boy can measure out exactly 7 pints without guessing at 
 the amount. Begin by fiUing the 5-pint vessel." 
 
 6. Same, except 5 and 7 given to get 8. ("Begin with 5.") 
 c. Same, except 4 and 9 given to get 7. ("Begin with 4.") 
 
THE STANFORD REVISION AND ITS HISTORY 
 
 23 
 
 THE VOCABULARY TEST 
 
 Time required. 
 
 1. orange. . . . 
 
 2. bon&e 
 
 3. roar 
 
 4. gown 
 
 5. tap 
 
 6. scorch 
 
 7. puddle 
 
 8. envelope . . 
 
 9. straw 
 
 10. rule 
 
 11. haste 
 
 12. afloat 
 
 13. eye-lash. . . 
 
 14. copper. . . . 
 
 15. health 
 
 Score 
 
 51. pecuharity 
 
 52. coinage 
 
 53. mosaic 
 
 54. bewail 
 
 55. disproportionate. 
 
 56. dilapidated 
 
 57. charter 
 
 58. conscientious . . . . 
 
 59. avarice 
 
 60. artless 
 
 61. priceless 
 
 62. swaddle 
 
 63. tolerate 
 
 64. gelatinous 
 
 65. depredation 
 
 16. curse - 66. promontory. 
 
 17. guitar. 
 
 18. mellow 
 
 19. pork 
 
 20. impolite. . . 
 
 21. plumbing. . 
 
 22. outward. . . 
 
 23. lecture. . . . 
 
 24. dungeon. . . 
 
 25. southern. . 
 
 26. noticeable. 
 
 27. muzzle 
 
 28. quake 
 
 29. civil 
 
 30. treasury. . . 
 
 31 . reception. . 
 
 32. ramble 
 
 33. skill. 
 
 67. frustrate. 
 
 68. milksop 
 
 69. philanthropy. 
 
 70. irony 
 
 71. lotus 
 
 72. drabble 
 
 73. harpy 
 
 74. embody 
 
 75. infuse 
 
 76. flaunt 
 
 77. declivity 
 
 ■78. fen 
 
 79. ochre 
 
 80. exaltation. . . . 
 -81. incrustation. . 
 
 82. laity 
 
 83. selectman. . . . 
 
 34. misuse ^84. sapient. 
 
 35. iosure 85. retroactive . . 
 
 36. stave 86. achromatic. . 
 
 37. regard 87. ambergris. . . 
 
 38. nerve '88. casuistry. . . . 
 
 39. crunch 89. paleology — 
 
 40. juggler 90. perfunctory. . 
 
 41. majesty 91. precipitancy. 
 
 42. brunette '92. theosophy. . . 
 
 43. snip '<"93. piscatorial. . . 
 
 44. apish '94. sudorific 
 
 ■-45. sportive. 
 
 46. hysterics. 
 
 47. Mars 
 
 48. repose 
 
 49. shrewd. 
 
 '95. parterre 
 
 ■^'96. homunculus. 
 
 97. cameo 
 
 '98. shagreen. . . . 
 
 99. limpet. 
 
 50. forfeit -100. complot 
 
 Note : To get the entire vocabulary, multiply the number of correct 
 definitio ns by 180. 
 
24 STANFORD REVISION OF BINET-SIMON SCALE 
 
 The Fable Test 
 
 "Fables, you know, are little stories which teach us a lesson. Now 
 I am going to read a fable to you. Listen carefully and when I am 
 through I wiU ask you to tell what lesson the fable teaches us." 
 
 After reading each fable say, "What lesson does that teach us? 
 Ask also if fable has been heard before. 
 
 A. Hercules and the Wagoner 
 
 A man was driving along a country road, when the wheels suddenly 
 sank in a deep rut. The man did nothing but look at the wagon and 
 call loudly to Hercules to come and help him. Hercules came up, 
 looked at the man, and said: "Put your shoulder to the wheel, my 
 man, and whip up your oxen." Then he went away and left the driver. 
 Lesson 
 
 B. The Milkmaid and Hbe Plans 
 
 A milkmaid was carrying her paU of milk on her head, and was 
 thinking to herself thus: "The money for this milk wiU buy 4 hens; 
 the hens will lay at least 100 eggs; the eggs will produce at least 75 
 chicks; and with the money which the chicks wiU bring I can buy a 
 new dress to wear instead of the ragged oae I have on." At this mom- 
 ent she looked down at herseH, trying to think how she would look in 
 her new dress; but as she did so the pail of milk slipped from her head 
 and dashed upon the groimd. Thus all her imaginary schemes perished 
 in a moment. 
 Lesson 
 
 C. The Fox and the Crow 
 n 
 A crow, having stolen a bit of meat, perched in a tree and held it 
 in her beak. A fox, seeing her, wished to secure the meat, and spoke 
 to the crow thus: "How handsome you are! and I have heard that the 
 beauty of your voice is equal to that of your form and feathers. Will 
 you not sing for me, so that I may judge whether this is true?" The 
 crow was so i)leased that she opened her mouth to sing and dropped 
 the meat, which the fox immediately ate. 
 Lesson 
 
 D. The Farmer and the Stork 
 
 A farmer set some traps to catch cranes which had been eating his 
 seed. With them he caught a stork. The stork, which had not really 
 been steaUng, begged the farmer to spare his hfe, saying that he was 
 a bird of excellent character, that he was not at all hke the cranes, and 
 that the farmer should have pity on him. But the farmer said: "I 
 have caught you with these robbers, the cranes, and you have got to 
 die with them." 
 Lesson 
 
THE STANFORD REVISION AND ITS HISTORY 25 
 
 E. The Miller, His Son, and the Donkey 
 
 A miller and his son were driving their donkey to a neighboring 
 town to sell him. They had not gone far when a child saw them and 
 cried out: "What fools those fellows are to be trudging along on foot 
 when one of them might be riding." The old man, hearing this, made 
 his son get on the donkey, whUe he himself walked. Soon they came 
 upon some men. "Look," said one of them, "see that lazy boy riding 
 while his old father has to walk." On hearing this the miller made his 
 son get off, and he climbed upon the donkey himself. Farther on they 
 met a company of women, who shouted out: "Why, you lazy old 
 fellow, to ride along so comfortably while your poor boy there can 
 hardly keep pace by the side of you!" And so the good-natured 
 miller took his boy up behind ViJTn and both of them rode. As they 
 came to the fown a citizen said to them, "Why, you cruel fellows! 
 you two are better able to carrjr the poor donkey than he is to carry 
 you." "Very well," said the miller, "we will try." So both of them 
 jumped to the ground, got some ropes, tied the donkey's legs to a pole 
 and tried to carry him. But as they crossed the bridge the donkey 
 became frightened, kicked loose and fell into the stream. 
 Lesson 
 
CHAPTER II 
 
 THE DISTRIBUTION OF INTELLIGENCE 
 
 The question as to the manner in which intelligence 
 is distributed relates itself at once to fundamental 
 issues in biological theory and suggests social and 
 educational problems of great importance. Perhaps 
 the most vital question which can be asked by any 
 nation of any age is the following: "How 'high is the 
 average level of mental endowment among our people, 
 and how frequent are the various grades of abihty 
 above and below the average?" 
 
 With the development of standardized intelligence 
 tests we are approaching, for the first time, a possible 
 answer to this question. The future of such tests is 
 guaranteed by the importance of the problems which 
 they undertake to answer. This would still be true 
 even if it could be shown that all the mental tests 
 which have yet been devised or suggested are of little 
 worth. 
 
 Difficulties in Finding the True Distribution of Intelli- 
 gence 
 
 In view of the large number of investigations made 
 with the Binet-Simon tests in many countries, the 
 light which these have thrown upon the distribution 
 of intelligence is less than might have been expected. 
 The reasons for this are various. In the first place, 
 the number of children tested by any one investigator, 
 .and particularly the number at any one age, has 
 usually fallen short of that required for far-reaching 
 conclusions. If we could mass the results of different 
 investigators the problem would be made much easier; 
 
 26 
 
THE DISTKIBXJTION OF INTELLIGENCE 27 
 
 but owing to the lack of uniformity in the methods by 
 which the data have been secured, this is usually a 
 dangerous procedure. Because of the small numbers 
 we can seldom be sure that the children tested were 
 representative. Educational advantages, social status, 
 racial differences, and other possible selective influences^ 
 must be taken into accovmt. To get representative 
 children of a given age is especially difficult, and it is 
 by no means easy even when questions of education, 
 social status and race hOTeJbeen eliminated. Studies 
 of the progress of school children through the grades 
 have shown that children of any given age are scattered 
 over an astonishing range of grades. It has been a 
 common mistake to select certain school grades for 
 the testing and to suppose that the results secured 
 could be used as norms for the ages foimd in those 
 grades. 
 
 One factor or another has entered to impair the 
 value of almost every experiment with the scale. 
 Kuhhnann, for example, in his tests of 1000 children, 
 avoided selection by examining all the children enrolled 
 in the pubUc schools of a small middle-class city; but 
 his examiners were untrained. Fewer tests by trained 
 examiners would have made his experiment of greater 
 value in several respects. Binet's 1908 scale was based ( 
 on tests of only 200 children, 15 to 25 of each age, and 
 these were situated in one of the poorest quarters of 
 Paris. What further selection of subjects took place 
 in this experiment we are not informed. Bobertag's 
 subjects were in the main pupils attending the Volks- 
 schule, and these are known to have a lower average 
 level of mental endowment than pupils attending the 
 higher schools. Goddard's numbers were fairly large, 
 but the tests were made by persons of limited training 
 and at a rate (as high as thirty per day for one tester) 
 
28 STANrOED REVISION OP BINET-SIMON SCALE 
 
 which rendered thoroughness impossible. Some of 
 the tests of Terman and Childs were made by only 
 partly-trained examiners, and here, again, too little 
 attention was paid to social class and age selection. 
 
 In like manner it would be easy to point out serious 
 shortcomings in every study which has been made 
 with the Binet scale, including those of Jeronutti at 
 Rome, Treves and Saffiotti at Milan, Dr. Anna Schu- 
 bert at St. Petersburg, Mrs. Wolkowitsch at Moscow, 
 Bloch and Preiss at Kattowitz, Miss Johnston at Shef- 
 field, Winch in London, Rogers and Mclntyre at 
 Aberdeen, Decroly at Brussels, Levistre and Morl^ in 
 Paris, Miss Dougherty in Kansas City, Dr. Morse and 
 Miss Strong in South Carolina, Dr. Rowe in Michigan, 
 the Weintrobs in New York City, Dr. Schmidt in 
 Chicago, etc. 
 
 But even had the procedure and the method of 
 selecting cases not been at fault in these studies, the 
 results would still have been misleading as regards 
 the distribution of intelligence, owing to the acknowl- 
 edged imperfection of the scale used. The arrange- 
 ment of tests in the earlier years magnified decidedly 
 the amount and range of superior abiUty, and to a 
 corresponding degree covered up the presence of re- 
 tardation. At the upper end of the scale the tests 
 were so few and so unsatisfactory that individual 
 differences above the level of eleven years were hardly 
 brought out at all. Only at the middle point was the 
 scale reasonably accurate. 
 
 As regards the distribution of intelUgence we believe 
 that the Stanford 1914-1915 data have more than 
 ordinary significance, and for reasons which it may be 
 well to enumerate: 
 
 (1) The children were as nearly representative of 
 the different ages as it is possible to get. The method 
 
THE DISTRIBUTION OF INTELLIGENCE 29 
 
 was to select a school attended by all the children of 
 school age in the community, and to test the children 
 of the various ages in whatever grades they might 
 happen to be. This obviates accidental age selection 
 at least for the years 7 to 13, inclusive. It is possible, 
 however, that six-year-old and fourteen-year-old school 
 children are not quite representative of children of 
 those ages, since mentally retarded six-year-olds are 
 likely to enter school a year late and since a consider- 
 able number of fourteen-year-olds have been promoted 
 to the high school. 
 
 (2) The children tested were all within two months 
 of a birthday. Our curve of distribution for nine- 
 year intelligence, for example, really represents the 
 distribution of intelhgence for nine-year olds, and not 
 that of children ranging all the way from eight and a 
 haK to nine and a half years. 
 
 (3) The schools selected for the tests were such as 
 almost any one would classify as middle-class. Few 
 children attending them were either from very wealthy 
 or very poor homes. The only exception to this rule 
 was in the case of Reno, where all the children within 
 two months of a birthday were tested throughout 
 the city. The large majority of these, however, were 
 from homes of average wealth and culture. Only 2 
 per cent., in fact, were classified by the teachers as of 
 "very inferior" social status, and only 1.6 per cent, as^ 
 of "very superior" social status. '-~ 
 
 (4) Care was taken to avoid racial differences and 
 the difficulties due to lack of familiarity with the 
 language. None of the children was foreign-bom 
 and only a few were of other than western European 
 descent. The names were chiefly EngUsh, Irish, 
 Scotch and German, with a few Swedish, French, 
 Spanish, Itahan, and Portuguese. Tests of Spanish^ 
 
30 STANFORD REVISION OF BINET-SIMON SCALE 
 
 Italian and Portuguese children were eliminated from 
 our study of distribution, for the reason that in west- 
 ern cities children of these nationalities are likely to 
 belong to unfavorably selected classes. We are justi- 
 fied in beheving, therefore, that the distribution of 
 intelligence among our subjects is less influenced by 
 extraneous factors than has been the case in other 
 studies of this kind. 
 
 (5) The numbers tested were relatively large, 
 namely 80 to 120 at each age from 6 to 14 years, with 
 somewhat fewer at 5 and 15. Moreover, the use of 
 only such children as were within two months of a 
 birthday greatly enhances the value of the numbers 
 
 , 1 employed. In each school this near-birthday group 
 ■ composed approximately one-third of all the children 
 in attendance, and by the laws of chance we can be 
 sure that the results are approximately as they would 
 have been had the entire school enrollment been 
 tested, that is, 3000 instead of 1000. This plan has the 
 further advantage that three times as many schools 
 were sampled as would otherwise have been the case; 
 and if it happened, in spite of the care exercised, that 
 some of the schools were below average in social status, 
 this would probably be counterbalanced by other 
 schools somewhat above average. 
 
 (6) The scale by which the mental ages were com- 
 j puted is certainly much more accurate than Binet's 
 
 or the earlier revisions. As already stated, the tests 
 i were worked over until the average mental age se- 
 cured at each level approximately coincided with the 
 physical age. In this way the scale was made of 
 nearly equal accuracy at every point. 
 
 (7) Correcting the rather large error of the scale 
 at the upper and lower ranges gives another advantage 
 of extreme importance, for it enables us to combine 
 
THE DISTRIBUTION OF INTELLIGENCE 31 
 
 the intelligence quotients of the children of all ages 
 into a single surface of distribution. As long as in- 
 telligence was reckoned in terms of years and months 
 of retardation or acceleration it was of course not 
 permissible to combine the distributions for different 
 ages. The range of mental ages is approximately 
 twice as great at 10 years as at 5 years, so that one 
 year of retardation or acceleration at 5 is equivalent 
 to two years of retardation or acceleration at 10. Ac- 
 cordingly, to combine the results for children of several 
 different ages so as to show what percent of the entire 
 number are retarded or accelerated one year, two 
 years, three years, etc., is an absurd procedure. The 
 range of intelligence quotients, however, as measured 
 by the revised scale, is not far from constant from 
 five to fourteen years, and these may therefore be 
 combined iato a single surface of distribution. The 
 curve thus obtained differs from those of the indi- 
 vidual years only in being somewhat more regular. 
 
 (8) Finally, though by no means least in importance, 
 the tests from which the following curves of distribu- 
 tion were derived were made with more than ordinary 
 care. The examiners were trained, the procedure was 
 kept as uniform as possible and the scoring was all 
 done by one person. Wherever evidence was found 
 of mistaken procedure, the examiner was questioned, 
 and if the records of that exairdner for that test were 
 not comparable with the others, they were thrown 
 out* 
 
 After making the necessary eliminations because of 
 incomplete testing, foreign parentage, etc., there 
 remained 981 children, distributed as shown herewith. 
 
 TABLE 2 
 
 Age 4 5 6 7 8 9 10 11 12 13 14 15 16 
 
 Cases.... 16 54 117 92 100 113 87 97 83 98 82 46 14 
 
32 STANFOKD KEVISION OF BINET-SIMON SCALE 
 
 The Distribution of Intelligence for the Ages Separately 
 
 The intelligence quotients were calcvilated for all 
 the children and those for a given year were then 
 thrown into groups so that each group represented 
 the cases include in a range of ten points intelligence 
 quotient. The middle group includes the intelligence 
 quotients from 96 to 105; the ascending groups include 
 in order those from 106-115, 116-125, 126-135, and 
 136-145. The corresponding descending groups are 
 86-95, 76-85, 66-75, and 56-65. Only one case tested 
 below 56, a girl of 8 years who had an intelligence 
 quotient of 51. None tested above 145. Graphs 1 to 
 13 show the results of this grouping for each age sepa- 
 rately from 4 to 16. 
 
 It is evident at a glance at these graphs that the 
 distribution of intelligence quotients is fairly sym- 
 metrical at each age from 5 to 14. At 14 the number 
 of exceptionally superior children decreases, as we 
 should expect, since a few of the brightest have by 
 that age finished the eighth grade. At 15 the intelU- 
 gence quotients range on either side of 90 as a median, 
 and at 16 years on either side of 80 as a median. 
 This, again, is what we should expect, because we 
 know from other facts that a majority of school 
 retardates are below average in intelligence. The 17 
 4-year-olds averaged high, with a median intelligence 
 quotient of 103. It is reasonably certain, however, 
 that children of this age attending school are usually 
 somewhat beyond the average in intelligence. 
 
 It Mdll be noted that at every year from 5 to 14 the 
 middle group is the largest and that the groups on 
 either side decrease in size somewhat regularly with 
 increasing distance from the median. In the lower 
 years, however, the 106-115 and 116-125 groups are 
 larger than the Sfl-Qj^ onri Vfi-Sfi o-T-nnr^o T-ooTAonfi NroNr 
 
THE DISTEIBXJTION OF INTELLIGENCE 
 
 33 
 
 SG-6S 6e-7S 7e-8S 8G-9S 3G-I05 lOe-IIS IIB-IZS IZG-IJS l2&-/-f-S 
 9'l, 13'/. 32-/. Zri. 18% f/. 
 
 Graph 1. Distribution of intelligence quotients of 16 kindergaxten 
 
 children, age 4 years. (These pupils are a selected group and 
 
 test high.) 
 
 S6-65 b6-7S 76-S5 86-95 SG-IOS IO&-IIS II&-IZS IZe-l3S I3&-H-S 
 IZS7, iS'l. 27.S'I. IZSr. 01 li?t 
 
 Graph 2. Distribution of inteUigence quotients of 54 kindergarten 
 children, age 5 years. (Median at 102.) 
 
34 STANFORD REVISION OF BINET-SIMON SCALE 
 
 _c 
 
 5G-e5 66-7S 76-85 8&-35 SS-IOS lOb-IIS llb-IZS l2e-l3S I36-/1-S 
 ri. 67. I7t 38'/. 24-'/. 31. el. a 
 
 Graph 3. Distribution of intelligence quotients of 117 imselected 
 6-year-olds. (Median at 103.) 
 
 .5G-G5 66 - 7S 7& -85 66 -95 96 -105 106 -1/5 ll6 -126 IZ6-I35 li6-l+5 
 
 2 7. :}3y. i7sy. 35'/. 277. 1/7. jjy. 17. 
 
 Graph 4. Distribution of intelligence quotients of 93 unselected 
 7-year-oIds. (Median at 102.) 
 
THE DISTRIBUTION OF INTELLIGENCE 35 
 
 SG-eS 66-75 76-8S S6-3S Se-IOS lOG-IIS II6-I2S IZe-l35 i:i6-/4-S 
 /'/. 0'/. ?•/. 16.5'/. ^07. 20.5 y. 12 7. 3'/- 
 
 Graph 5. Distribution of intelligence quotients of 98 unselected 
 8-year-olds. (Median at 101-|-.) 
 
 56-65 66-175 7(>-B5 8&-3S S&-l05IOb-IIS Ili,-I2£ l2(>-l35l3(,-l4-5 
 zy. IZX 211. 38'/. Z3.51. 6,t /'/. 11. 
 
 Graph 6. Distribution of intelligence quotients of 113 unselected 
 9-year-olds. (Median at 100.5.) 
 
36 STANFORD REVISION OF BINET-SIMON SCALE 
 
 zn 
 
 se-es ee-rs 76 -as 86 -as 96-/os /oe-i/s //6-/2S/26-/3s /36-/-f-s 
 
 2jy. 237. l&.Sy. 3V/. 26'/. /■f-'A /'/. /'/. 
 
 Graph 7. Distribution of intelligence quotients of 87 unselected 
 lO-year-olds. (Median at 103.) 
 
 c 
 
 ± 
 
 56-6S &B-7S 76-85 86-95 36/03 IO&-JIS n6-l25 t26-IJ5l5B-H-5 
 1.3% 2S% 63'l. 2037. J2-/. 2/.77. IIS'/. ^7. /J/- 
 
 Graph 8. Distribution of intelligence quotients of 79 unselected 
 11-year-olds. (Median at 98.) 
 
THE DISTRIBUTION OF INTELLIGENCE 37 
 
 56-6S 66-7i5 76-85 SB -35 36-105 IOe-115 ll6-IZ5IZe-l35 I3e-I4-S 
 I'/. 71 111 225'/. 337. 185'/. &'/. /'/. 
 
 Graph 10. Distribution of inteUigence quotients of 98 unselected 
 13-year-olds. (Median at 96.5.) 
 
 A few of the brightest 13-year-olds had been eliminated from this 
 group by promotion to the high school and were not tested. 
 
 5B-G5 &G-75 76-8586-95 36-105 106-115 116- 125 I26-I55I36-J4-5 
 ZS7. 12-/. 2557. J'h7. 22 7. 3 7'/. 
 
 Graph 11. Distribution of inteUigence quotients of 82 children 14 
 years of age. (Median at 97+.) 
 
 Many of the brightest 14-year-olds had been promoted to the high 
 school and do not appear in the above graph. 
 
38 STANFORD REVISION OF BINET-SIMON SCALE 
 
 5&-&S bb-75' 7i>-8S 86-95 9b-l05 IDi^-i 15 I li,-IZS Hb-IJS I3C>-H-S 
 2.x b'l. Zb'l. 3b'/, 26'/. +■/. 
 
 Geaph 12. Distribution of intelligence quotients of 47 children, age 
 15 years (over-age for grade). (Median 90.) 
 Most of the average and superior 15-year-olds had been promoted 
 to the high school and do not appear in the above graph. 
 
 Sb-&S Gb-7S 7b-8S S6-3S 3b-/0S lOb-IIS llb-IZS IZ&- I3S- /3&-/4-S 
 m ZZt 351 22V. 7% 
 
 Graph 13. Distribution of intelligence quotients of 14 children aee 
 
 lb years (over-age for grade). (Median 80.) 
 ^J^°i ^\ ayerage and superior IG-year-olds had been promoted to 
 the high school and do not appear m the above graph. 
 
THE DISTRIBUTION OF INT^ILLIGENCE 39 
 
 on the other side. The most noticeable lack of sym- 
 metry occurs at ages 5, 6, and 14. This is due in part 
 to a certain amount of unavoidable selection. The 
 five-year-olds were enrolled in kindergartens, and since 
 school attendance at this age is not compulsory, we 
 can not be sure that kindergar'Fgncnildren represent 
 the median inteUigence for five-year-olds. The same 
 is true of six-year-olds, though to a less extent. In 
 both cases the distribution of intelligence quotients 
 suggests that at these ages inferior children are some- 
 what less Ukely to be found in school than those of 
 superior endowment. The reverse is the case at 14, 
 since a few of the brighter children of that age have 
 completed the eighth grade and have either dropped 
 out or passed on to the high school. It is possible 
 that a few children under 14 have managed to evade 
 the compulsory attendance laws and are not in school, 
 but it is certain that in the cities and towns where our 
 testing was done the amount of such evasion was 
 practically negligible. 
 
 On the whole, it is evident that the distribution .of 
 intelligence quotients is fairly regular_an.d-Unif orm in 
 The variouji years. This is fm-ther shown by the fact 
 that the range including the middle 50 percent of the 
 inteUigence quotients does not vary greatly between 
 5 and 14 years. Combining each two successive years 
 in order to overcome the chance effects of the limited 
 number of children of any one age, we have the ac- 
 companying table in which, it is of interest to note, 
 the distribution of intelligence quotients for the differ- 
 ent age-levels furnishes no support to the very generally 
 accepted belief that variability materially increases at 
 adolescence. As far as 14, at least, there is no evidence 
 that this occurs. 
 
40 STANFORD REVISION OF BINET-SIMON SCALE 
 
 Ages 
 
 6 and 6 combined 
 
 7 and 8 combined 
 9 and 10 combined 
 
 II and 12 combined 
 13 and 14 combined 
 
 All ages combined 
 
 TABLE 3 
 Limits of quotient 
 including middle 50% 
 97 to 111 
 95+ to 111 
 94 to 108 
 92 to 108 
 90 to 105 
 
 92+ to 108 
 
 Eange of quotients 
 including middle 50% 
 15 
 16+ 
 
 15 , 
 
 17 
 16 
 
 16+ ' 
 
 The Distribution of Intelligence for the Ages Combined 
 As already explained, the corrected scale has the 
 advantage of enabling us to combine the intelligence 
 quotients of the children of different ages into a single 
 surface of distribution, something that we could not 
 do when the scale was too easy at some levels and 
 too hard at others. By combining ages 5 to 14, we 
 have the distribution shown in Graph 14. Ages 4, 15 
 and 16 have been omitted from this combined dis- 
 tribution because of the selection which has taken 
 place at these years.* 
 
 S6-&S6e-rS 76-8S 86-9S 3&-I05 10^-115 ll&-IZ5IZ&-l351^6-l'h5 
 ^St Z3l 5.67. 20.11 33.37. 23.11 9.0% 231. ^sr. 
 
 Graph 14. Distribution of intelligence quotients of 905 unselected 
 children, ages 5-14 years. (Median at 99.) 
 
 ^At 15 and 16 there is the additional reason, that growth at this 
 time is probably slowing down sufficiently to impair the validity of the 
 intelligence quotient. 
 
THE DISTRIBUTION OF INTELLIGENCE 
 
 41 
 
 Exception may be taken to this combined distribu- 
 tion on the groimd that it fails to take account of 
 possible selection which may have taken place at ages 
 5, 6, 13, and 14. As shown in Graph 15, however, the 
 distribution for ages 7 to 12 combined is httle different 
 from that for 5 to 14 combined. 
 
 =L 
 
 3= 
 
 5B-es ee-TS re-as Bess se-ios loe-iis iie-izs ize-iss i3e,-ii-s 
 
 .37. 1:87. 87. 137. 337. Zf-Jl. 3.87. 2'/. 77. 
 
 Graph 15. Distribution of intelligence quotients of 554 unselected 
 children 7-12 years of age. (Sexes combiQed.) 
 
 The intelUgence quotients may, of course, be grouped 
 in ranges of any desired extent. If the nimibers dealt 
 with had been larger, it would have been interesting 
 to group them in ranges of 5 instead of 10. With the 
 numbers available, however, the curves resulting from 
 this method of grouping would be much less regular than 
 when larger groups are used. On the other hand, if 
 ranges above 10 are used for the grouping, the distri- 
 bution becomes still more symmetrical. This may 
 be seen from Graph 16, which shows the relative sizes 
 of groups contained in ranges of 20, for ages 5 to 14 
 combined. 
 
42 STANFORD REVISION OF BINET-SIMON SCALE 
 
 Geaph 16. Distribution of intelligence quotients of 905 unselected 
 
 children, age 5-14 years. Intelligence quotients grouped in 
 
 ranges of 20. 
 
 Following is a comparison of the observed distri- 
 bution (Ages 5-14) with that called for by the theoretical 
 "normal" curve of distribution (the Gaussian curve): 
 
 TABLE 4 
 Intelligence Quotient Ranges 
 
 56-65 
 
 66-75 
 
 76-85 
 
 86-95 
 
 96-105 
 
 106-115 
 
 116-125 
 
 126-135 
 
 136-145 
 
 Obtained 
 Theoretical 
 
 .33 
 .4 
 
 2.3 
 3.1 
 
 8.6 
 11. 
 
 20.1 
 22. 
 
 33.9 
 
 27. 
 
 23.1 
 22. 
 
 9. 
 11. 
 
 2.3 
 3.1 
 
 .55 
 .4 
 
 The normal nature of the distribution of mental 
 ability is further borne out by the teachers' rankings 
 according to intelligence and school work, which were 
 made according to the form given in the appendix. 
 These rankings were made in a little more than half 
 
THE DISTRIBUTION OF INTELLIGENCE 
 
 43 
 
 the schools and included 489 children, about equally 
 divided between the sexes. The results are shown on 
 page 48. 
 
 The distribution shown iu the graphs of this chapter 
 are for the boys and girls combined. There are cer- 
 tain sex differences, however, which will be set forth 
 in Chapter III. We may ignore these for the present, 
 since they are not great, and proceed to an examination 
 of the frequency with which various departures from 
 the normal are encountered. 
 
 An examination of the distribution for all the ages 
 from 5 to 14, taken together, and for the sexes com- 
 bined, gave the following significant facts: 
 
 TABLE 5 
 lie lowest 1 percent go to 70 or below; the highest 1 percent reach 130 or above 
 
 2 
 
 
 ' " 73 
 
 
 
 " 2 
 
 " 128 " " 
 
 3 
 
 
 ' " 76 
 
 
 
 " 3 " 
 
 " 125 " " 
 
 5 
 
 
 ' " 78 
 
 
 
 " 5 " 
 
 " 122 " " 
 
 10 
 
 
 ' " 85 
 
 
 
 " 10 " 
 
 " 116 " " 
 
 15 
 
 
 ' " 88 
 
 
 
 " 15 
 
 " 113 " " 
 
 20 
 
 
 ' " 91 
 
 
 
 " 20 
 
 " 110 " " 
 
 25 
 
 
 ' " 92+ 
 
 
 
 " 25 " 
 
 " 108 " " 
 
 33.3 
 
 
 ' " 95 
 
 
 
 " 33.3 " 
 
 " 106+ •■' " 
 
 A perfectly normal distribution would cause 93 per- 
 cent of the cases to fall between 76-125, instead of 
 the observed 94.7 percent; and 99.2 percent between 
 66-135, instead of the observed 99.3 percent. 
 
 Or, to put some of these facts of distribution in 
 another form, we may say, speaking approximately: 
 
 The child reaching 110 is equaled or excelled by 20 out of 100 
 
 " " " 115 " " " " " 10 " " 100 
 
 " " " 125 " " " " " 3 " " 100 
 
 " " 130 " " " " " 1 " " 100 
 
 Again, for those whose intelligence quotient is below 
 100: 
 
 The child testing at 90 is equaled or excelled by 80 out of 100 
 
 u li u a g5 a u u u u qq u a ^qq 
 
 (( U ti It rre U tl (i a tt q't it ti iqq 
 
 i( tt IC tl YQ (( (( ei it II QQ » (( J^QQ 
 
44 STANFORD REVISION Or BINET-SIMON SCALE 
 
 When we examine the above data, it is difficxilt to 
 avoid the conclusion that superior intelligence of any- 
 given degree occurs with approximately the same 
 frequency as intelUgence which is inferior to a corres- 
 pondiag degree. The usual assumption, however, is 
 that extreme degrees of mental deficiency are much 
 more nimaerous than extreme degrees of mental 
 superiority. As far as intelUgence quotients between 
 60 and 140 are concerned, our figures do not support 
 this assumption.^ As regards the relative frequency 
 of intelligence quotients below 60 and above 140, the 
 assumption is in all probability valid; for while all idiot 
 and most imbecile children have an iatelligence quotient 
 as low as 50, there are extremely few cases of budding 
 genius which reach as high as 150. Indeed, notwith- 
 standing diligent search, the writer has found only a 
 few cases testing above 150, and only two testing as 
 high as 170.' 
 
 The significance of various intelligence quotients 
 will be dealt with more fully in another chapter. It is 
 
 ' This statement requires some modification in view of the fact that 
 our data were collected entirely from children who were attending 
 ^.hlin snhoills. There are, of course, in any community a few children 
 with inteUigence quotients between 60 and 80 who are either kept at 
 home or placed in institutions. No investigation seems to have been 
 made which would show what proportion of such children are not iu 
 school, but our experience suggests that it is very smaU. At any rate, 
 relatively few children testing as high as 65 or 70 are sent to an institu- 
 tion until they have first been tried for several years in the schools, 
 usually until well toward adolescence. It is well known that only a small 
 minority with an inteUigence quotient of 75 to 80 ever get iato an 
 iastitution for the feeble-miaded. 
 
 ^ This is not to deny that cases of considerably higher intelligence 
 quotient are to be found. A five-year-old child reported by Miss 
 Langenbeck seems to have tested not far from ten years. If the test 
 can be accepted at its face value, the child, therefore, had an intelUgence 
 quotient of about 200. See A study of a five-year-old child Pedaq 
 Seminary, March, 1915, 65-88. More recently Dr. Leta S. HolUng- 
 worth has favored us with a copy of a test of an eight-year boy whose 
 intelUgence quotient is 190. 
 
THE DISTRIBUTION OP INTELLIGENCE 45 
 
 already evident, however, that the term "feeble- 
 mindedness" is a matter of arbitrary definition. In 
 one sense it could be said that a child with an intelli- 
 gence quotient of 85 or 90 is as truly feeble-minded as 
 one testing at 50, only he is mentally feeble to a much 
 less degree. It becomes merely a question of the 
 amount of intelUgence necessary to enable one to get 
 along tolerably with his fellows and to keep somewhere 
 in sight of them in the thousand and one kinds of 
 competition in which success depends upon mental 
 ability. The definition of feeble-mindedness, too, is 
 a constantly shifting one. Until recent years the 
 standard was one which would have classed a majority 
 of children having two-thirds intelUgence (intelligence 
 quotient 67) in the normal group. Even yet the usual 
 medical standard is no higher than this. The child 
 of moron grade is rarely classified by the physician 
 as "feeble-minded." Social workers, psychologists, 
 and criminologists, however, are constantly meeting 
 facts which would seem to justify the application of 
 the term feeble-minded to many children with three- 
 fourths intelUgence (intelligence quotient 75). It is 
 possible that the development of civilization, with 
 its inevitable increase in the complexity of social and 
 industrial Ufe, will raise the standard of mental nor- 
 mality higher still. 
 
 But whatever the standard, the number of borderline 
 and debatable cases will probably be greater than the 
 number of those whom all would agree to call feeble- 
 minded. The attempt to classify all children as either 
 definitely feeble-minded or definitely normal involves 
 exactly the same difficulties as we should encounter 
 in trying to classify all adult men as either "normally 
 tall" or "abnormaUy short," and we may add that 
 
46 STANFOED REVISION OF BINET-SIMON SCALE 
 
 the one attempt is just about as much worth while 
 as the other. 
 
 To regard feeble-intelligence as always a disease, 
 which, like small-pox, one either has or does not have, 
 is a view which is contradicted by all we know about 
 the distribution of mental traits. Physicians find 
 special difficulty in freeing themselves from this fallacy, 
 since for them diagnosis consists essentially in deter- 
 mining the presence or absence of definitely patho- 
 logical conditions. 
 
 There is other evidence than that of mental tests 
 to support the hypothesis that intelligence is dis- 
 tributed in the manner indicated by our distribution 
 of intelligence quotients. It has often been shown 
 that a similar distribution results when teachers are 
 asked to classify children into three groups (or five 
 groups) according either to school success or intelU- 
 gence. Thus, Bobertag had teachers classify 2772 
 pupils into three groups according as their school 
 work was "unsatisfactory," "satisfactory," or "better 
 than satisfactory." The resulting classification showed 
 50.8 percent in the middle group, 25.7 percent in the 
 superior group, and 23.5 percent in the inferior group. 
 The numerous other studies which have been made 
 of teachers' marks give similar results, though in 
 some cases the curve shows a more noticeable tendency 
 to be skewed in the direction of superiority. 
 
 About half our teachers supplied for each of their 
 children tested the supplementary data called for on 
 the blank shown in the appendix. It will be noted 
 that Question 4 calls for a classification of the children 
 into five groups according to the quality of school 
 work, and Question 5 a similar classification on the 
 basis of the teacher's judgment as to a child's intelli- 
 
THE DISTRIBUTION OF INTELLIGENCE 47 
 
 gence. The classes were designated in the blank as 
 "very inferior," "inferior," "average," "superior" 
 and "very superior." The resulting distributions 
 are shown herewith. 
 
 TABLE 6 
 Peecents Rated 
 Very Very 
 
 Inferior Inferior Average Superior Superior 
 School work (503 ChU- 
 
 dren) 5.2 17.9 51.0 22.1 3.8 
 
 Teacher's judgment of 
 intelligence (489 
 Children) 3.4 14.4 55.8 23.1 3.3 
 
 If for quality of school work, we combine the two 
 superior groups and combine similarly the two inferior 
 groups, the distribution coincides remarkably with 
 that found by Bobertag. 
 
 TABLE 7 
 
 Inferior Average Superior 
 
 Bobertag 23.5 50.8 25 7 
 
 Ours 23.1 51.0 25^8 
 
 It is interesting to compare the teachers' groupings 
 for intelligence with those for school success, as shown 
 in Graphs 17 and 18. 
 
 The "piling up" of the intelligence distribution 
 in the direction toward the "superior" end indicates 
 that teachers are able to judge the degree of a child's 
 intelligence less objectively and therefore less accu- 
 rately than they judge the quality of his school work. 
 Personal factors are more hkely to enter into judgments 
 about intelUgence, and in case of uncertainty as to 
 the proper classification there is a natural tendency 
 to give the child the benefit of the doubt, even at 
 the risk of grading him too high." 
 
 * The relation between the intelligence tests and the teachers' judg- 
 ments of intelligence is treated in full in Chapter VI. 
 
48 STANFORD EEVISION OF BINET-SIMON SCALE 
 
 \/ery Inferior Inferior Averaje Superior Very supenvr 
 Z.Vj. I^n. 55 8t 231'/. 33'l.- 
 
 Graph 17. Distribution of teachers' rankings of 489 children ac- 
 cording to intelligence. 
 
 J 
 
 Very Inferior Inftrior Average Superior Very superior 
 5.Z'/. 17.9'/. 51'/. ZZl'i. 38'/. 
 
 Ghaph 18. Distribution of teachers' rankings of 603 children^ac- 
 cording to quality of school work. (Mostly the same children as 
 appear in Graph 17.) 
 
THE DISTRIBUTION OF INTELLIGENCE 49 
 
 The "Mental Ages" of 62 Normal Adults 
 The use of the Stanford revision with 30 business 
 men of moderate success and of very limited educa- 
 tional advantages gave a distribution of mental ages 
 differing little from that found with 32 high school 
 pupils pupils from 16 to 20 years of age. The results 
 for both groups are shown in tabular form. 
 
 TABLE 8 
 Mental Age 
 
 13 to 14 to 15 to 16 to 17 to 18 to 
 
 13-11 14^11 15-11 16-11 17-11 18-11 
 
 Business Men 1 6 7 8 6 2 
 
 H. S. Pupils 5 12 10 4 1 
 
 If we combine the business men with the high school 
 pupils who are over 16 years of age chronologically, 
 we have the distribution of mental ages shown in 
 Graph 19. It will be noted that the middle part of 
 the graph represents the "mental ages" falling within 
 the range of two years, namely 15 to 17. This range 
 we may designate as the "average adult" level. 
 
 Summary 
 
 1. The revised scale gives a median intelligence 
 quotient of approximately 100 when used with unse- 
 lected children of any age from 5 to 14. 
 
 2. The distribution of intelligence quotients for 
 unselected children of each age conforms fairly closely 
 to the Gaussian curve. This holds particularly for 
 our subjects of ages 7 to 13. 
 
 3. Since the revised scale yields the same form of 
 distribution of intelUgence quotients at each age, it 
 is permissible to combine the intelligence quotients 
 for the different ages from 5 to 13 or 14 into a single 
 surface of distribution. 
 
 4. The mental ages found by testing 30 uneducated 
 business men and 32 high school pupils over 16 years 
 of age range from the "inferior adult" level to the 
 "su perior adult" level, with t he greatest number at 
 
50 STANFORD EEVISION OF BINET-SIMON SCALE 
 
 l3tol3-ll li-t. 14-11 I5UIS-U I7UI7-II IShlg-lt 
 I.&7. ml, S3.77, l&Z% ■h.SZ 
 
 Graph 19. Mental ages of 62 adults, including 30 business men of 
 little education and 32 high school students over 16 years of age. 
 
CHAPTER III 
 
 THE RATE OF GROWTH AND THE VALIDITY 
 OF THE INTELLIGENCE QUOTIENT 
 
 The previous chapter showed that for unselected 
 children the distribution of intelUgence as measured 
 by the revised scale maintains a certain constancy 
 from 5 to 13 or 14 years, when the^degree of intelligence 
 is expressed iii^terws.j3jthAJ^!^^^nc^j2MM?nt. Any 
 givenlJeviaBon from the medl^^ occurs with much 
 the same frequency at all the ages. 
 
 The intelUgence of children has usually been esti- 
 mated, however, ia terms of years and months of 
 retardation or acceleration. Binet, while using this 
 method, reaUzed that a year of retardation is less 
 serious with older children than with younger, and 
 accordingly he suggested the rule that while a retarda- 
 tion of 2 years usually means feeble-mindedness in 
 children under ten years of age, older children should 
 not be regarded as feeble-minded unless retarded as 
 much as 3 years. This is obviously crude, but Binet 
 did not suggest any more definite adjustment to allow 
 for the decreasing significance of a given amount of 
 retardation in the upper years. Even this sUght 
 adjustment is often ignored by those who use the 
 scale. One person, after testing a large number of 
 juvenile delinquents ranging from 10 to 18 years in 
 age, lumps all the ages together and counts up the 
 number who were retarded 1 year, 2 years, 3 years, 
 4 years, etc., concluding finally that about 75 percent 
 of the total number were feeble-minded, since that 
 many were retarded 3 years or more. This error 
 appears again and again in the literature of Binet 
 testing. Others, starting from the same erroneous 
 
 51 
 
52 STANFORD REVISION OF BINET-SIMON SCALE 
 
 assumption, have defined "at-age" intelligence as 
 "that which is within one year of the child's physical 
 age and have expected to find the number of children 
 testing "at-age" to be the same at all chronological 
 ages. 
 
 It is obvious, however, from the distribution of 
 intelUgence quotients as shown in Chapter II, that 
 a given number of years of retardation can have no 
 definite meaning except in relation to the age of the 
 subject. Whatever the age of a group of non-selected 
 children, approximately the same percent will always 
 be included in any range of the intelUgence quotients. 
 As already shown, the middle fifty percent are at all 
 ages included in the range of about 92 or 93 intelUgence 
 quotient to 108 or 109 intelligence quotient. Trans- 
 muting these values into months, we have for 6-year- 
 olds, 50 percent included in a range of a Uttle less than 
 one year of mental age; while for 12-year-olds, the 
 middle 50 percent range over about twice this distance, 
 or nearly two years. Retardation of two years is 
 about as common at 12 years as retardation of one 
 year at 6; and either is about as common as retardation 
 of a year and a half at 9. That is, the curve of dis- 
 tribution of mental ages becomes progressively flat- 
 tened, the older the children with which we deal. 
 This is shown in Graphs 20, 21, and 22, which give 
 the distribution of mental ages for children of 6, 9, 
 and 12 years, respectively. 
 
 The range including 50 percent of the mental ages 
 increases in a fairly constant ratio from Age 6 to Age 
 14, as shown in Graph 23. 
 
 The use of the intelligence quotient as a means of 
 expressing a child's intelligence status is based, of 
 course, on the assumption that the intelligence quo- 
 
VALIDITY OF THE INTELLIGENCE QUOTIENT 
 
 53 
 
 -3 
 
 -2 
 
 0"/. 
 
 -; 5-7 
 737. 73'L 
 
 +1 +2 +3 
 
 IZ'U 27°/. 0'/. 
 
 Graph 20. Distribution of mental ages of the 117 unselected 6-year- 
 olds. 
 
 -f 
 
 -3 
 
 -2 
 
 -1 
 
 8-10 
 
 +1 
 
 +2 
 
 + 3 
 
 +■^ 
 
 p% 
 
 OX 
 
 ■h'/z'l. 
 
 16°/. 
 
 eoy. 
 
 15°/. 
 
 3°/. 
 
 /'/. 
 
 0'/. 
 
 Graph 21. Distribution of mental ages of the 113 unselected 9-year- 
 olds. 
 
 _r 
 
 -f- -3 -2 -/ tl-l3 +/ +2 +3 +-(- 
 
 0'/. 3.57. 12% 17 7. 4-3'/. 11:57. 8.57. 17. 07. 
 
 Graph 22. Distribution of mental ages of the 83 unselected 12-year- 
 
54 STANFORD REVISION OF BINET-SIMON SCALE 
 
 A^^ £ 
 
 10 morilh^ 
 
 
 /IjtS 
 
 13,4- TTyonThs 
 
 Ajn.10 
 
 /6 moTiTh!, 
 
 
 Aa^lZ 
 
 ZO moTjThi 
 
 
 
 Aaeli- 
 
 ZG -movThs 
 
 Graph 23. Showing range of months including the middle 50% of 
 mental ages at various years. 
 
 tient remains practically constant during the years of 
 mental growth; that, for example, the child of five 
 years who tests at 4 (intelligence quotient 80) will 
 at later ages have the mental ages shown in the follow- 
 ing figures: 
 
 TABLE 9 
 
 
 
 
 8 9 10 11 
 
 12 
 
 13 
 
 14 
 
 6.4 7.2 8 8.8 
 
 9.6 
 
 10.4 
 
 11.2 
 
 Physical Age 5 6 7 
 
 Mental Age.... 4 4.8 6.6 6.4 7.2 
 
 The facts which have already been presented argue 
 in favor of the validity of the intelUgence quotient 
 at least for Ages 5 to 13 or 14. It has been shown 
 that the distribution of intelligence quotients for 
 the different years remains essentially the same, and 
 that the distribution of mental ages (in terms of years 
 and months) flattens out in the upper years in approxi- 
 mately the expected ratio; 79 percent test within one 
 year of physical age at 6, 60 percent at 9, and 43 
 percent at 12. The percents called for at 9 and 12 by 
 a theoretically valid intelHgence quotient would be 
 59.25 and 39.5, granting 79 percent to be correct for 
 
VALIDITY OF THE INTELLIGENCE QUOTIENT 55 
 
 Age 6. The range of mental ages including the middle 
 50 percent of cases is 10 months at Age 6, and increases 
 in the succeeding years as shown in the accompanying 
 table. 
 
 TABLE 10 
 
 Observed Percentage Percentage of In- 
 
 Eange Including of Increase Over crease Called for by 
 
 Age Middle 50 Percent That of Year 6 a Theoretically Valid 
 
 4| ^^ Intelligence Quotient 
 
 8 13.4 months 34 33.3 
 
 10 16 months 60 67.6 
 
 12 20 months 100 100 
 
 The crucial test of the vaUdity of the intelligence 
 quotient would be to measure the intelUgence of the 
 same children several times during their period of 
 mental growth. No experiment of this kind appears 
 to have been made on any considerable scale, barring 
 a few repetitions of tests after an interval of only one 
 year. The results of such tests, however, support 
 in a general way the hypothesis that the intelligence 
 quotient of a given child tends to remain constant.' 
 The matter has been compUcated, however, by the 
 uneven inaccuracy of the Binet scale at different 
 levels. 
 
 Repeated tests are being made of a considerable 
 number of children with the Stanford revision, and 
 although the investigation is not complete at this 
 writing, the results of 140 such tests show that as far 
 as the age of 13 or 14, even when the tests are separated 
 by as much as five years, changes of 10 points in 12 
 are relatively rare. In general, it can be said that 
 the superior children of the first test are found superior 
 in the second, the average remain average, the inferior 
 
 'See W. Stem: Der Intelligenzquotient als Mass der kindlichen 
 Intelligenz, inbesondere der untemormalen. Zeitsch. f. Angewandte 
 Psychologie, 1916, Bd. II, Heft, 1-19. (Argues for the constancy of 
 the inteUigence quotient from 7-12.) 
 
56 STANFORD REVISION OF BINET-SIMON SCALE 
 
 remain inferior, the feeble-minded remain , feeble- 
 minded, and nearly always in approximately the 
 same degree. The most marked exceptions to this 
 rule are found with the feeble-minded, whose intelli- 
 gence quotient shows a tendency to decrease consid- 
 erably. 
 
 If future investigations should confirm the vaUdity 
 of the intelligence quotient and its necessary corol*- 
 laries, the practical consequences would be of the 
 greatest importance. It would mean that, after a 
 mental test consuming no more time than an ordinary 
 medical examination, the psychologist would be able 
 to predict, with some degree of accuracy, the future 
 of the child's mental development. There is nothing 
 else which the average parent would more Uke to 
 know about the child, and nothing else which would 
 prove of greater value in directing its education. 
 
 Whether the intelligence quotient holds even ap- 
 proximately with very young children, or with children 
 much beyond the age of 14, is a question on which 
 the data available afford little Ught. We are war- 
 ranted in believing, however, that general intelligence 
 practically ceases to develop by the age of 18 or 20 
 years. The mental age of high-grade morons appears 
 to change Uttle after the age of 14 or 15 years. With 
 normal children development continues a Uttle longer, 
 though at a decreasing rate. It is practically certain, 
 however, that growth of intelligence comes to a stand- 
 still somewhere in the later years of adolescence, and 
 that the cessation is gradual rather than sudden. It 
 is evident, also, that beyond the time when the cessa- 
 tion begins, the intelligence quotient rapidly loses its 
 meaning. The 12-year-old moron with a mental age 
 of 8 years has an inteUigence quotient of 67, which 
 
VALIDITY OP THE INTELLIGENCE QUOTIENT 57 
 
 at this period of life probably indicates his mental 
 status fairly well. When 6 years old, the same child 
 probably had a mental age of about 4 years, and when 
 9 years old, a mental age not far from 6 years. But 
 inasmuch as mental growth slows down rapidly some- 
 time after the age of 14 or 15, the mental age of this 
 subject is unlikely ever to go beyond 10 years. Sup- 
 posing it to stop at 10, the inteUigence quotient, if 
 we continued to use it, would be reduced to 50 at 
 the age of 20 years, to 25 at the age of 40 years, etc. 
 Such a use of the term, of course, would be absurd, 
 since the subject's intelligence is really a constant 
 quantity throughout adult life. 
 
 If it could be shown that mental growth continues 
 its earlier rate up to a certain age, say 16, and then 
 stopped quite suddenly, we could continue to use the 
 intelligence quotient with adults of any age by merely 
 ignoring the years beyond 16. That is, all adults, 
 for purpose of reckoning the intelligence quotient, 
 would be regarded as exactly 16 years of age.^' There 
 are two difficulties, however, with a plan of this kind: 
 (1) mental growth probably does not come to a stand- 
 still suddenly; and (2) the time of its cessation is 
 not accurately known. 
 
 A practical way to get at the matter is to adopt 
 some hypothesis of this general nature, a quite tenta- 
 tive one, of course and by subjecting it to the pragmatic 
 test of experiment, to see whether it is in harmony 
 with ascertainable facts. If the hypothesis first 
 adopted is unable to satisfy the requirements, it may 
 be altered or replaced by a better. In this way, by 
 
 2 Such a scheme would demand, however, that the upper end of the 
 scale be so framed that the intelligence of superior adults as well as 
 that of superior immature subjects could be expressed in an inteUigence 
 quotient above 100. 
 
58 STANFOED REVISION OF BINET-SIMON SCALE 
 
 checking up every step and profiting from our mis- 
 takes, we should be able finally to arrive at a solution 
 of /the problem which would be correct enough for 
 all practical purposes. 
 
 / Some of the data which have been presented would 
 sfeem to justify the assumption, as a tentative working 
 basis, that mental age maintains approximately a 
 /fixed ratio to chronological age until the latter has 
 /reached about 14 or 15 years, that during the next 
 I year or two the ratio diminishes, and that after the 
 chronological age of 17 or 18 years, mental age re- 
 mains constant. According to this hypothesis, the 
 intelligence quotient would be a proper expression 
 of the intellectual status with subjects as old as 14 or 
 15 years. 
 
 This is the hypothesis which has guided us in the 
 extension of the scale at the upper end. We have at 
 least succeeded in shaping it in such manner that a 
 child, for example, whose mental age at 7 was 8 years 
 (intelligence quotient about 115) wiU have at 14 a 
 mental age in the neighborhood of 16 (intelligence 
 quotient about 115), with the possibility of further 
 increasing his mental age considerably before growth 
 ceases. Our high school students usually test between 
 15 and 17 years, as do also Knollin's and Zeidler's 
 business men. College students average slightly 
 higher, as we should expect from the fact that they 
 belong to a selected group. 
 
 It will be understood naturally that the numbers 
 expressing such mental ages as 17 years, 18 years, 
 19 years, etc., have only a conventional value and 
 are not to be interpreted Uterally. Their use offers 
 a feasible, if arbitrary, method of enabling the superior 
 adolescent or adult to earn a quantitative expression 
 
VALIDITY OF THE INTELLIGENCE QUOTIENT 69 
 
 of his superiority in the tests. Tentatively, we may 
 use the intelligence quotient with normal adults by 
 merely ignoring years of age beyond 16. That is, 
 the adult's chronological age is always, for this pur- 
 pose, reckoned as 16. 
 
 Further trial of our revision by repeating the tests 
 between early and late adolescence, supplemented 
 by tests, of different groups of adults, will determine 
 the adequacy of our arrangement. It is not offered 
 as a finished product, but as material for further 
 elaboration and refinement. 
 
 Although the intelligence quotient maintains a 
 fairly constant value from rather early in childhood 
 imtil late in the growing period in the case of children 
 of all grades of intelligence above mental deficiency, 
 it is possible that this constancy may not be main- 
 tained with defectives, particularly those of low grade. 
 The child of 4 years who has a mental age of 1 year 
 is an idiot and may never develop higher than a mental 
 level of 2 years, perhaps not so high. His intelligence 
 quotient of 25 at 4 years will gradually diminish, say 
 to 15, at the age when mental maturity is attained in 
 the normal child. We must look to the institutions 
 where low-grade defectives are abundant to supply 
 the facts regarding mental growth in these subjects. 
 
 In closing this discussion it may be interesting to 
 point out that the facts presented in this and the 
 preceding chapter are not entirely in harmony with 
 certain wide-spread opinions about the rate of mental 
 growth. The view has often been expressed that 
 intelligence normally develops by alternate leaps and 
 rests. Starting from observations on certain instincts, 
 the doctrine of "nascent stages" has come to be applied 
 to the phenomena of mental development generally 
 
60 STANFORD REVISION OF BINET-SIMON SCALE 
 
 and is now almost a dogma in the literature of child 
 psychology. Researches are rapidly showing, how- 
 ever, that instincts themselves have less a Minerva- 
 bu-th than we had supposed, a fact which Freudian 
 psychology has demonstrated in the case of the 
 sex instincts. As far as general intelligence is con- 
 cerned, there is little evidence of periodicity or irregu- 
 larity. If such periodicity or irregularity occurred, 
 the intelligence quotient of the developing child 
 would be now high, now low, instead of maintaining 
 a fairly constant value.' 
 
 The facts we have presented offer little hope to the 
 parent who would like to believe that his backward 
 boy who is 6 or 8 years old will "catch up" in the 
 supposed spurt of adolescence. Indeed, the much- 
 taUced-of adolescent spurt begins to look Uke a myth. 
 
 These same facts, however, furnish some consolation 
 to the parents of a young genius. It has been the 
 custom for teachers and even for some psychologists 
 to inspire in them a dismal and uneasy fear that such 
 a child is in danger of retrograde development. We 
 hear of great men who in childhood were famous 
 blockheads, and of genius children who became numb- 
 skulls! Perhaps it would not be safe to assert that 
 such cases do not occur, for logic teaches that uni- 
 versal negatives are hard to establish. If they do 
 occur, we may suppose that a concrete example will 
 sometime come to light, vouched for by the necessary 
 scientific proof. 
 
 ' Baldwin has recently shown that physical growth also proceeds at 
 a nearly uniform rate from 7 to 14 years of age, and that a child's 
 physical status, as expressed in height and weight, maintains a fairly 
 constant position, with reference to norms, from age 6 or 7 through 
 adolescence. Bird T. Baldwin: Physical Growth and School Proaress. 
 BvU. U. S. Bur. of Ed., 1914, No. 581. 
 
VALIDITY OF THE INTELLIGENCE QUOTIENT 61 
 
 Summary 
 
 1. Retardation or acceleration of any given number 
 of years has no meaning apart from the age of the 
 child, and the method of expressing intelligence status 
 in absolute years only should be abandoned. 
 
 2. The distribution of intelligence quotients for 
 the separate years argues strongly in favor of the 
 intelligence quotient as a valid method of expressing 
 a child's development status, at least for the years 
 5 to 14. 
 
 3. Data are presented which indicate that the 
 intelUgence quotient of a child of any grade of intelli- 
 gence remains fairly constant until well into the period 
 of adolescence. Doubt is thrown upon the existence 
 of the supposed "nascent stages," the "adolescent 
 spurt," and other popularly assumed irregularities 
 of mental growth. 
 
CHAPTER IV 
 
 Sex Differences 
 
 Our revised scale has been constructed by massing 
 the results from boys and girls, and our discussion 
 of the distribution of intelligence in Chapter II took 
 no account of sex differences. However, when we 
 treat the intelligence quotients of the boys and girls 
 separately, we find a somewhat constant, though rather 
 slight superiority of the girls from Ages 5 to 13, with 
 the exception of Age 10. At 14 years the boys appear 
 to be about as superior to the girls as the girls were 
 superior to the boys at 5. This is shown in Graph 24, 
 which gives the median intelligence quotient for the 
 boys and girls separately at each age from 5 to 14. 
 
 Graphs 25-34 show the distribution of intelligence 
 quotients for the sexes separately, when grouped in 
 ranges of ten, 56-65, 66-75, 76-85, 86-95, etc. Be- 
 cause of the small number of boys or girls in any one 
 year, successive ages have been combined for the 
 graphs, as 5-6, 7-8, 9-10, etc. 
 
 If, now, we combine the intelligence quotients for 
 all ages from 5 to 14, inclusive, we have Graphs 35 
 and 36 for boys and for girls, respectively. 
 
 Comparison of the sexes with regard to the range 
 of intelligence quotient that includes the middle 50 
 percent shows that half the boys lie between 91-107 
 and half the girls between 93 and 109. Table 11 
 shows the frequency of some of the more extreme 
 degrees of variation according to sex. 
 
 62 
 
SEX DIFFERENCES 
 
 63 
 
 30 
 
 .60 
 
 .*0 
 
 .ZO 
 
 s 
 
 Boy 5 1-00 
 Girls 1.01- 
 
 Graph 24. Showing median intelligence quotients for boys and girls 
 separately at each age, number of boys, 457; girls, 448. 
 
 6 
 
 7 
 
 8 
 
 3 
 
 10 
 
 II 
 
 IZ 
 
 13 
 
 H- 
 
 .93 
 
 1.01 
 
 m 
 
 .38 
 
 1.03 
 
 36 
 
 .37 
 
 .56 
 
 100 
 
 1.05 
 
 I.DZ 
 
 I.OZ 
 
 Wl 
 
 Ifi3 
 
 1.01 
 
 .93 
 
 37 
 
 .96 
 
64 STANFORD REVISION OF BINET-SIMON SCALE 
 
 ^e-es ee-75 re-8s 86-95 96-io5 loe-iis 11&-125 126-135 i3S-i4-5 
 
 I'l. ll'l. ZZ'L 36'/. 1831 9-/. Z5'/. 
 
 Graph 25. Distribution of intelligence quotients of 87 boys, ages 5 
 and 6 combined. 
 
 J6-6S 66-Z5 76-85 8&-95 9e- 105 I0e-ll5 iie-IZ5 125-135 l3&-i4-i 
 I'l. 5'/. I'f-y, 3Sy. Z3'/. 14--/. &■/. /■/. 
 
 Graph 26. Distribution of intelligence quotients of 87 girls, ages 5 
 and 6 combined . 
 
SEX DIFFERENCES 
 
 65 
 
 c 
 
 n= 
 
 i 
 
 J6-e5 66-75 76-85 86-95 96-/05 W6-ll5 iie-125 I2G-I35I3G-I4-5 
 
 n. n. 'h.5'1. iQ5'l. 4-1'/. 2:sy. /o'/. z-u /% 
 
 Graph 27. 
 
 Distribution of intelligence quotients of 100 boys, ages 
 7 and 8 combined. 
 
 56-65 £6-75 76-85 86-95 Se-I05 106-115 IIG-/Z5 /ZB-/35/3e-l-t-^ 
 /•/. 7'/. 19'/. 531 Z1--/. /Z'l. 4-V. 
 
 Graph 28. Distribution of intelligence quotients of 91 girls, ages 7 
 and 8 combined. 
 
66 STANFORD REVISION OF BINET-SIMON SCALE 
 
 56-65 66-75 76-85 86-35 96-/05 I0G-Il5 I/6-IZ5 i26-i35>36-l4-5 
 6.5'/. 207, i-l'l. zv/. a'l. /'/. 
 
 Graph 29. Distribution of intelligence quotients of 92 boys, ages 9 
 and 10 combined. 
 
 zC 
 
 56-65 66-75 76-85 86-95 3B-I05 106-1/5 / 16-125 /2e-/35 I3G-I4-5 
 ^% 85°/. 19.5°/, 3/.57. ZG7. 9°/. /'/. Z°l. 
 
 Geaph 30. Distribution of intelligence quotients of 108 girls, ages 
 9 and 10 combined. 
 
SEX DIFFERENCES 
 
 67 
 
 ^6-85 6e-7S 76-85 8e-9S S6 -103 lOB-Z/S 116-125 I2&-I35 I3&-I4-5 
 1.5% 5'J. 13'/. 24-y. 287. 207. S'J. 3'/. 
 
 Graph 31. Distribution of intelligence quotients of 74 boys, ages 
 11 and 12 combined. 
 
 X 
 
 5G-G5 86-75 76-85 8B-95 96-105 I06-II5 118-125 128-135 136-/4-^ 
 27. 9V. 17'/. 32'/. 21-'/. 12 5'/. 2'/. /% 
 
 Graph 32. Distribution of intelligence quotients of 88 girls, ages 
 11 and 12 combined. 
 
68 STANFORD REVISION OF BINET-SIMON SCALE 
 
 L 
 
 se-es e6-7J re-as ae-as se-ios /oe-i/s iie-125 ize-us/se-zi-s 
 zy. e-'i. in. zoi. 32% zz'i. s'l. 
 
 Graph 33. Distribution of intelligence quotients of 106 boys, ages 
 13 and 14 combined. 
 
 lU 
 
 56-&5 6B-75 76-86 86 -9S 96-/05 /06-l/S /I6 -125 IZG-/55li&-lt5 
 5.5'/. 8'/. 271 35'/. 175'/. SS7. 1.31. 
 
 Graph 34. Distribution of intelligence quotients of 74 girls, ages 
 13 and 14 combined. 
 
SEX DIFFERENCES 
 
 69 
 
 3- 
 
 S6-eS GG-YS re-SS 86-95" 9B-I0S I06-IISIIG-IZ5 I26-I3S/3G-/4-S 
 t3'h 2.171. lO.e?]. ZIJ37. J3.J5r. 22.01 8.0€j. 2J7l. 
 
 Graph 35. Distribution of intelligence quotients of 457 boys, 5-14 
 years of age. 
 
 56-G5 66-7S 76-85 86-95 3G-I0S IDG-II5 II6-IZS /ze-I3S l3G-/fS 
 .22'/. 2.Q77. Gf7l. 18.97'/. 33.7'/. 2^.33'/. ID.01-1. 2f5'/. IjH 
 
 Graph 36. Distribution of intelligence quotients of 448 girls, 6-14 
 years of age. 
 
70 STANFORD REVISION OF BINET-SIMON SCALE 
 
 TABLE 11 
 
 Distribution of Certain Intelligence Quotients in 457 Boys and 448 
 
 Girls 
 
 
 Total 
 60 or 
 lower 
 
 Total 
 70 or 
 lower 
 
 Total 
 75 or 
 lower 
 
 Total 
 125 or 
 
 higher 
 
 Total 
 130 or 
 higher 
 
 Total 
 140 or 
 higher 
 
 Boys. . . 
 Girls. . . 
 
 No, 
 1 
 1 
 
 % 
 .21% 
 .22% 
 
 No. 
 4 
 5 
 
 % 
 
 .87% 
 1.11% 
 
 No. 
 13 
 14 
 
 % 
 2.83% 
 3.12% 
 
 No. 
 
 11 
 
 17 
 
 % 
 2.39% 
 3.47% 
 
 No. 
 5 
 8 
 
 % 
 1.08% 
 1.74% 
 
 No. 
 
 3 
 
 % 
 .66% 
 
 The facts we have presented indicate that, apart 
 from a slight superiority of the girls from 5 to 12 years, 
 the distribution of intelligence is much the same for 
 the sexes. There is no evidence of any wider range 
 of intelligence among boys, such as has commonly 
 been supposed to exist. The difference, if any exists, 
 seems to be in the other direction. A slightly larger 
 percent of girls than of boys falls to 75 or below, which 
 is the point frequently taken as indicating feeble- 
 mindedness, and a decidedly larger percent of girls 
 reaches as high as 125. The range that includes the 
 middle 50 percent is almost exactly the same in extent 
 for the two sexes. This is all quite contrary to the 
 traditional belief that both feeble-ihindedness and 
 exceptionally superior ability are more frequent with 
 boys than with girls.' 
 
 Although the superiority of the girls is not great in 
 amount, it appears over a long enough period to 
 suggest that it may represent a genuine difference 
 and not some accidental condition of the experiment. 
 
 1 In support of our results we are glad to cite the study of Mrs. Leta 
 Hollingworth: "The frequency of amentia aa related to sex," The 
 Medical Record, Oct. 25, 1913, which is an analysis of 1000 cases ex- 
 amined in the New York Clearing House for Mental Defectives. See 
 also, by the same author: "Variability as related to sex differences 
 in achievement, Am. J. Sociology, Jan., 1914, pp. 510-530; and the 
 comparative variabihty of the sexes at birth, same Journal Nov. 
 1914, pp. 335-370. 
 
SEX DIFFERENCES 71 
 
 It was first thought that part of the difference might 
 be accounted for by the fact that two-thirds of the 
 tests were made by women and only one-third by 
 men, but when the intelligence quotients were classi- 
 fied according to the sex of the examiners no such 
 influence was discoverable. There remains the possi- 
 bihty that the superiority of the girls in the tests 
 may be the result of a somewhat more ready faciUty 
 of the girls in the use of language, or of their greater 
 willingness to respond. 
 
 Fortunately the supplementary information fur- 
 nished by the teachers affords us valuable data as 
 to the genuineness of the sex difference in inteUigence 
 quotients. On page 48 was given the grouping of 
 476 children, boys and girls together, according to 
 the teachers' estimates of intelligence. When these 
 estimates are summarized for the boys and girls sep- 
 arately (Table 12), the superiority of girls appears 
 only in one respect: viz., 12, or 4.8 percent of the girls 
 are classified in the "very superior" group, as con- 
 trasted with 3, or 1.3 percent of the boys. 
 
 TABLE 12 
 
 Teachers' Estimates op Intelligence for 229 Boys and 247 Girls, 
 
 BY Sex 
 Percent Very Very 
 
 Baulked Inferior Inferior Average Superior Superior 
 
 229 Boys 3.9 14.4 56.7 23.5 1.3 
 
 247Girk 3.2 13.7 57.0 21.0 4.8 
 
 Table 12 is for the ages 5 to 14 combined. The 
 teachers' estimates for the ages 13 and 14 were treated 
 separately from the other ages in order to find out 
 whether the tendency of the girls to lose their advan- 
 tage in intelligence quotient at this point is confirmed 
 or contradicted by the judgment of the teachers. 
 The results, shown in Table 13, bear out the tests. 
 
72 STANFOED REVISION OF BINET-SIMON SCALE 
 
 for while the teachers have judged the intelligence 
 
 of the girls at earlier ages as fully equal, if not superior 
 
 to that of the boys, they give the advantage at age 
 
 13-14 to the boys. The table shows 19.5 percent 
 
 of the boys of 13 and 14 years of age classed as below 
 
 average, as contrasted with 24.5 percent of the girls; 
 
 on the other hand, 26 percent of the boys are classed 
 
 as above average, as contrasted with 13.5 percent of 
 
 the girls. 
 
 TABLE 13 
 
 Teachers' Estimates of Intelligence of Boys and Girls for the 
 Ages 5-12 and 13-14 
 
 Percent Very Very 
 
 Banked Inferior Inferior Average Superior Superior 
 
 Ages 5-12 Boys 3.2 14.7 57.3 22.9 1.6 
 
 Combined Girls 3.8 11.9 56.1 22.3 5.7 
 
 Ages 13- Boys 6.5 13.0 54.3 26.0 0.0 
 
 14 Combined.. Girls 0.0 24.5 62.0 13.5 0.0 
 
 In like manner we have compared the boys and 
 girls with reference to the quality of their school work, 
 as judged by the teachers. When we classify the 
 judgments for the ages 5-12 separately from those 
 for 13-14, we have Table 14. 
 
 TABLE 14 
 
 Teachers' Estimates of the Quality op the School Work of 
 Boys and Girls for the Ages 5-12 and 13-14 
 Percent Very Very 
 
 Eanked Inferior Inferior Average Superior Superior 
 
 Boys 3.8 11.1 60.0 23.8 1.1 
 
 5-12 Girls 3.3 12.6 57.7 20.8 5.3 
 
 Ages Boys 4.1 26.5 45.0 22.5 2.0 
 
 13-14 Girls 2.4 19.5 53.6 22.0 2.4 
 
 Table 14 agrees with the tests in showing a larger 
 number of cases of greatly superior ability in school 
 work among girls than among boys from 5 to 12 years. 
 The data for Ages 13-14 agree with the tests less 
 closely, for, while the boys are less inferior to the 
 
SEX DIFFERENCES 
 
 73 
 
 girls than in the ages 5-12, they are still somewhat 
 inferior. 
 
 There remains still another means of checking up 
 the evidence of the tests as to the relative inteUigence 
 of boys and girls; we can compare their age-grade 
 distribution in school. Fortxmately, our data enable 
 us to do this for all the children tested. Table 15 
 gives the age-grade distribution for Ages 7 to 14. Ages 
 5 and 6 are left out of account because children of 
 this age have not had time to become retarded or 
 accelerated in school, and those above 14 are eliminated 
 because they represent a selected group — the "left- 
 overs." 
 
 TABLE 15 
 Age-Grade Distribution of Boys and op Girls fob the Ages 7 to 
 
 
 
 
 14. 
 
 (In Percents) 
 
 
 
 
 Age 
 
 Grade 
 
 I 
 
 II 
 
 III 
 
 IV 
 
 V 
 
 VI 
 
 VII 
 
 VIII 
 
 7 
 
 Boys 
 
 Girls 
 
 Boys 
 
 Girk 
 
 Boys 
 
 Girls 
 
 Boys 
 
 Girls 
 
 Boys 
 
 Girls 
 
 Boys 
 
 Girls 
 
 Boys 
 
 Girls 
 
 Boys 
 
 Girls 
 
 77.7 
 76.2 
 
 22.3 
 21.5 
 
 2.5 
 
 24.0 
 18.2 
 
 2.0 
 2.5 
 
 15.5 
 14.0 
 
 1.9 
 3.5 
 
 25.0 
 16.4 
 
 2.8 
 2.0 
 
 20.0 
 35.2 
 
 
 
 35.2 
 
 2.7 
 9.1 
 
 
 8 
 
 22.0 
 27.0 
 
 3.9 
 
 5.2 
 
 52.0 
 52.5 
 
 
 9 
 
 32.8 
 26.1 
 
 2.8 
 8.1 
 
 5.3 
 
 
 46.2 
 50.8 
 
 
 10 
 
 25.0 
 22.5 
 
 8.4 
 9.3 
 
 13.3 
 
 
 3.4 
 
 
 44.4 
 51.0 
 
 
 11 
 
 31.6 
 16.4 
 
 10.8 
 9.1 
 
 10.3 
 2.6 
 
 2.2 
 3.0 
 
 34.3 
 37.2 
 
 2.3 
 
 12 
 
 32.4 
 32.0 
 
 15.5 
 5.4 
 
 2.2 
 
 
 40.6 
 47.9 
 
 
 
 2.5 
 
 13 
 
 38.0 
 35.0 
 
 24.5 
 24.0 
 
 27.7 
 40.5 
 
 5.2 
 16.2 
 
 14 
 
 13.3 
 39.5 
 
 57.6 
 33.3 
 
74 STANFORD REVISION OF BINET-SIMON SCALE 
 
 Inspection of Table 15 will show that the results 
 lack uniformity. At Age 7, the age-grade status 
 of the girls is slightly better; at 8, the boys have a 
 shade the advantage; at 9, the girls; at 10, the boys; 
 at 11, 12 and 13, the girls are much in advance; while 
 at 14, the boys are the first time decidedly ahead. 
 On the whole, we may say that there is httle difference 
 for Ages 7, 8, 9, and 10; that for the next three years 
 the girls are much more advanced than the boys; 
 and that at 14 the boys have much the advantage. 
 
 Ignoring Year 7, since at this age pupils have had 
 little time to become retarded or accelerated, we are 
 justified in grouping the ages together as follows: 
 Years 8, 9, and 10; years 11, 12, and 13; and finally. 
 Year 14 by itself. Table 16 shows the percent of 
 boys and girls retarded or accelerated 1, 2, 3, or 4 
 years in each of these age-groups. 
 
 TABLE 16 
 
 Peecbnt of Boys and Gihls Retarded or Accelerated in School 
 
 BY 1, 2, 3, OR 4 Grades in Various Age-groups 
 
 Age 
 
 Sex 
 
 —4 
 
 —3 
 
 —2 
 
 —1 
 
 Normal 
 
 + 1 
 
 +2 
 
 +3 
 
 +4 
 
 Ages 
 
 8, 9, 10 
 
 combined 
 
 Boys. . . 
 Girls. . . 
 
 
 
 1.4 
 4.6 
 
 27.0 
 25.3 
 
 48.1 
 51.3 
 
 21.1 
 16.0 
 
 2.1 
 2.6 
 
 
 
 Ages 
 11, 12, 13 
 combined 
 
 Boys. . . 
 Girls. . . 
 
 1.5 
 
 10.0 
 .8 
 
 12.3 
 8.0 
 
 34.6 
 27.5 
 
 33.0 
 42.0 
 
 8.5 
 20.1 
 
 1.6 
 
 
 
 Age 
 14 
 
 Boys. . . 
 Girls. . . 
 
 2.2 
 3.3 
 
 2.2 
 
 24. S 
 24.2 
 
 13.3 
 39.3 
 
 57.8 
 33.3 
 
 
 
 
 
SEX DIFFERENCES 
 
 75 
 
 TABLE 17 
 
 Percent op Boys and Girls Retarded or Accelerated in School 
 BY 1, 2, 3, OR 4 Grades, for the Ages 8 to 14 Combined 
 
 
 —4 
 
 —3 
 
 —2 
 
 —1 
 
 Normal 
 
 + 1 
 
 + 2 
 
 +3 
 
 +4 
 
 Boys 
 
 .95 
 
 4.47 
 
 9.58 
 
 28.11 
 
 43.13 
 
 12.77 
 
 .95 
 
 
 
 Girls 
 
 .32 
 
 .32 
 
 8.11 
 
 27.59 
 
 45.45 
 
 15.90 
 
 1.94 
 
 .32 
 
 
 Table 17 shows the percent of boys and girls retarded 
 or accelerated 1, 2, 3, or 4 years for all the ages 8-14 
 combined. It should be emphasized, however, that 
 the facts we want to know are best disclosed in Table 
 16, and that the evidence goes to show that the grade 
 progress of our boys and girls differs little up to, and 
 including Age 10, that for the next three years the girls 
 are clearly in advance, and that the reverse is the case at 
 14- In the main, therefore, the school progress of our 
 subjects agrees with the intelligence tests, with the teachers' 
 estimates of intelligence, and with the teachers' judgments 
 of the quality of the school work, in showing a sex differ- 
 ence which is in favor of the girls before 14, and in favor 
 of the boys thereafter. 
 
 Before accepting this conclusion there is one other 
 factor to be taken into account which might help to 
 explain the apparent superiority of the boys at Age 14. 
 A certain amount of selection has taken place in this 
 age-group. A considerable number of the 14-year-olds 
 have been promoted to the high school, and these are 
 not included in our group of subjects of this age. This 
 has doubtless occurred more often with the girls than 
 the boys, for we have already showed that marked 
 school acceleration occurs much oftener with girls 
 than with boys at the ages 12 and 13 years. At Age 
 
76 STANFOBD REVISION OF BINET-SIMON SCALE 
 
 12 there are 9.1 percent of the girls in Grade VII and 
 2.5 percent in Grade VIII, as compared with only 
 2.7 percent of the boys in Grade VII and none at all 
 in Grade VIII. Similarly, at Age 13 there are 16.2 
 percent of the girls in Grade VIII as compared with 
 only 5.2 percent of the boys. If all our 13-year-olds 
 in Grade VIII should be promoted to the high school 
 at the end of the year, the number of 13-year-old girls 
 receiving such promotion would accordingly be more 
 than three times as great as the number of boys. If 
 this situation holds true generally, it can not be safely 
 ignored in making a comparative study of the intelli- 
 gence of boys and girls at the age of 14. Even at 13, 
 unequal selection appears to have taken place to no 
 small degree, as would appear from the following 
 age-grade distribution (in percents) of 13-year-old 
 boys and girls: 
 
 TABLE 18 
 
 
 HI 
 
 IV 
 
 V 
 
 VI 
 
 VII 
 
 VIII 
 
 13 Boys. . . . 
 
 . 3.4 
 
 10.3 
 
 15.5 
 
 38 
 
 27.7 
 
 5.2 
 
 year 
 
 olds Girls. . . . 
 
 
 2.6 
 
 5.4 
 
 35 
 
 40.5 
 
 16.2 
 
 The foregoing distribution would suggest that our 
 13-year-old boys are almost free from any selection 
 as far as promotion to the high school is concerned, 
 but that probably 5 percent or more of the girls who 
 ought to be present at this age are not in our group. 
 Comparison of the relative number of boys and girls 
 tested at different ages fully confirms this suspicion. 
 Table 19 shows that, while the number of girls found 
 in the grades equals or exceeds the number of boys 
 at every age but one below 13, yet at 13 and 14 the 
 girls make up only about 41 percent of the entire 
 number. This is significant when it is remembered 
 that, in all the schools where testing was done, all 
 
SEX DIFFERENCES 77 
 
 the boys and girls below the high school were tested 
 who were within two months of a birthday, whatever 
 grade they may have been in. By the laws of chance 
 the number of boys and girls found at each age ought 
 to have been nearly equal, barring selective influences. 
 
 TABLE 19 
 
 Percent the Gikls Fokm of the Entire Number of Pupils in 
 Grades Below the High School at Each Age 
 
 Age S 6 7 8 9 10 11 12 13 14 15 16 
 
 Percent... 50 60 49.5 46 51.3 57.5 56 53 41 41.5 45 28.6 
 
 The only possible conclusion seems to be that the 
 apparent superiority of boys at the age of 14, as well as 
 also their diminished inferiority at 13, is due solely to 
 the unequal selection which has taken place at these ages. 
 The results of the tests themselves, the teachers' 
 estimates of inteUigence, the teachers' judgments 
 about the quaUty of school work, and the age-grade 
 distribution, offer four separate and distinct Unes of 
 evidence pointing in this direction. The same four 
 lines of inquiry are also in general agreement in show- 
 ing a distinct, though slight superiority of the girls 
 in the ages below 13. 
 
 Unfortunately, most of the studies made with the 
 Binet tests throw httle light on sex differences. In 
 only two studies besides our own have the subjects 
 tested been nearly enough non-selected to make such 
 a comparison worth while, namely, in Goddard's 
 tests of 1500 Vineland school children and in Kuhl- 
 mann's tests of 1000 Faribault school children. Kuhl- 
 mann, however, has not analyzed his data for the 
 sexes separately, and Goddard has done so only to 
 the extent of giving the percent of boys and girls 
 testing 1, 2, 3, 4, or more years above or below age. 
 
78 STANFORD EEVISION OF BINET-SIMON SCALE 
 
 Even this is given by Goddard only for all the ages 
 taken together, a procedure which ignores the unequal 
 significance of a given number of years of retardation 
 with children of different ages. However, his data 
 for the ages combined agree with our own in indicating 
 a slight superiority of the girls. 
 
 TABLE 20 
 
 Sex Differences as Shown by the Binet Tests (Goddaed) 
 
 — 2 years — 1 year At age +1 jear +2 years 
 
 Percents or more or more or more 
 
 Boys 18.5 23 34.5 20 4 
 
 Girls 18.5 17 36.5 23 5 
 
 Bloch and Preiss made comparisons for sex differ- 
 ences in their tests of 79 boys and 71 girls aged 7 to 
 11 years. However, their results, which indicated a 
 marked superiority of the boys, throw no light on the 
 question of real sex differences, for the reason that 
 their subjects had been selected from a large number 
 as being supposedly "average" in intelUgence, and we 
 have no means of checking up the effect of this selec- 
 tion. 
 
 The only other Binet results thus far published 
 which may be used for comparative purposes are those 
 of Yerkes and Bridges, who present the sex differences 
 found in the use of their Point Scale with 760 grammar 
 school children from the kindergarten to the eighth 
 grade. The school chosen was located in a "medium 
 to poor" district, but otherwise there seems to have 
 been no selection of subjects which could have influ- 
 enced sex differences except the fact that in this study, 
 as in our own, the 14 and 15-year-olds tested were 
 composed wholly of those who had not progressed 
 in school beyond the eighth grade. 
 
 To make comparison easier, Yerkes' and Bridges' 
 curves showing the average scores earned by boys 
 
SEX DIFFERENCES 79 
 
 and girls of different ages are reproduced here. We 
 have chosen the curves obtained by excluding the 
 children of non-English-speaking parents. When the 
 latter were included, the curves crossed and re-crossed 
 so often as to have no clear significance. 
 
 It will be noted that the results of Yerkes and Bridges 
 are not altogether in harmony with our own. The 
 two scales agree in that both show a superiority of 
 the girls in the earlier ages and a superiority of the 
 boys at Ages 14^15. The latter, in all probability, 
 has the same cause in both cases, namely, the more 
 frequent elimination of 13, 14, and 15-year-old girls 
 from the grades by promotion. Yerkes and Bridges, 
 however, seem not to have considered this possibility. 
 In the middle ages the results of the two studies are 
 quite in contrast. 
 
 In evaluating these somewhat contradictory find- 
 ings it should be remembered, (1) that the Stanford 
 data are based on more than twice as many children 
 as those entering into the Yerkes-Bridges curve; (2) 
 that all of our children were within two months of a 
 birthday, thus obviating large possible errors likely 
 to result from dividing a small number of children 
 with age differences ranging up to one year into sex 
 groups; and (3) that the number of tests in the Stan- 
 ford revision is much larger than that included in the 
 Yerkes-Bridges scale, thus reducing the part played 
 by chance. 
 
 In conclusion, we may say that the evidence seems 
 to us to point to the existence of a small sex difference 
 in intelligence, which, but for the influence of selection, 
 would probably be in favor of the |,irls at all ages from 
 5 to 13 or 14 at least. It should be emphasized, how- 
 ever, that the difference is small, amounting to no 
 
80 STANFORD REVISION OF BINET-SIMON SCALE 
 90 
 
 
 
 
 
 
 
 
 
 
 
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 ' 
 
 
 
 
 
 
 
 
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 / 
 
 A- 
 
 
 
 
 
 
 
 
 
 
 if 
 It 
 1/ 
 
 
 
 
 
 
 
 
 
 
 ^ 
 
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 • 
 
 
 
 
 
 
 
 
 
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 / /■ 
 
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 (/ 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 ll 
 1 
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 f 1 
 
 1 
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 / 
 
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 A- S e> 7 8 9 10 II IZ iz 14- !£" 
 
 AvEBAGE Scores Earned by 468 Boys and Giels of Different 
 Ages with the Yerkes-Beidges Point Scale 
 
SEX DIFFERENCES 81 
 
 more than 6 percent in terms of intelligence quotient 
 at any age, and at most ages from only 2 percent to 
 4 percent. In view of the wide distribution of intelli- 
 gence in each sex (from 50 to 150 intelligence quotient), 
 a difference of 2-4 percent in median intelligence 
 would be practically negligible, even if it were dem- 
 onstrably genuine. The difference actually foimd is 
 so small that it might conceivably result from a sex 
 difference in temperamental traits having nothing 
 to do with intelligence, such, for example, as a differ- 
 ence in willingness to attempt a novel task, difference 
 La timidity, or what not. We prefer not to indulge 
 in speculation. At any rate we find no reason to 
 share the opinion voiced by Yerkes and Bridges "that 
 at certain ages serious injustice will be done to individ- 
 uals by evaluating their scores in the light of norms 
 which do not take account of sex differences." 
 
 Finally, the individual tests were examined sep- 
 arately for sex differences. Since the number of our 
 pupils of one sex was ordinarily not larger than 40 to 
 50 at one age, it was found that the increase in the 
 percent passing in successive years was so irregular 
 as to be very confusing. One way out of this difficulty 
 is to mass together the percents of boys (or girls) 
 passing a test at three separate age levels: the age 
 at which the test appears in the scale, and the adjoining 
 ages above and below. We have not deemed a sex 
 difference worth noting unless it appeared in all of 
 these three successive age levels and to such an extent 
 that the superiority averaged 10 percent for the three 
 ages taken together. This is, of course, an arbitrary 
 basis, but some such plan is necessary to escape the 
 confusion and contradiction engendered by chance 
 variations due to small numbers. As will be seen 
 
82 STANFORD REVISION OF BINET-8IMON SCALE 
 
 from Table 21, the number of tests in which significant 
 sex differences appear, is not large— only 19 out of 58.' 
 
 TABLE 21 
 
 Sex Differences in Individtjai Tests 
 
 SUPEEIOKITY OF BOTS 
 
 StrPBRIOEITY OF GlBLS 
 
 Tests in which the super- 
 iority of BoTS in three 
 successive years averaged 
 10 percent or more 
 
 Amount 
 
 of such 
 
 superiority 
 
 in 
 
 percent 
 
 Tests in which the super- 
 iority of GiBLS ia three 
 successive years averaged 
 10 percent or more 
 
 Amount 
 
 of such 
 
 superiority 
 
 in 
 
 percent 
 
 Arithmetical reasoning, 
 
 XIV 
 President and king, XIV 
 Form-board, IX 
 Fables, XII 
 Makiag change, IX 
 Hands of clock, XIV 
 Ball and field, XII 
 Similarities, XII 
 Induction, XIV 
 
 33 
 25 
 20 
 15 
 15 
 12 
 11 
 11 
 10 
 
 Designs from memory, X 
 Aesthetic compr., V 
 Ball and field, VIII 
 Giving differences, VII 
 Comprehension, VIII 
 4 digits backwards, IX 
 
 6 digits, X 
 
 7 digits, XIV 
 Bow-knot, VII 
 Rh3Tnes, IX 
 
 19 
 17 
 16 
 13 
 12 
 11 
 10 
 10 
 10 
 10 
 
 Smaller differences were found in favor of the boys 
 in Copying a Diamond (VII), Giving Easy Similarities 
 (VIII), Naming the Months (VIII), and Defining 
 Abstract Words (XII) ; in favor of the girls ia Repeat- 
 ing 5 Digits (VII), Naming the Days of the Week 
 (VII) and Hard Comprehension (XII). 
 
 We refrain from extended comment on the list 
 of tests in which sex differences have been found. 
 It will probably agree badly enough with anyone's 
 a priori expectations. There are apparent contra- 
 dictions, also, as well as surprises. We have no theory 
 
 " The tests of Years 3 and 4, and those of the "average adult" and 
 "superior adult" were left out of this comparison because of insufficient 
 data. 
 
SEX DIFFERENCES 83 
 
 to explain why the girls are superior on the ball and 
 field test of Year VIII (score 2) and the boys on the 
 same test at Year XII (score 3); or why the boys 
 are better in the tests of giving similarities, and the 
 girls iQ the test of giving differences. Perhaps we 
 should have expected the superiority of the boys in 
 arithmetical reasoning, the form-board, and making 
 change; likewise the superiority of the girls in aesthetic 
 comparison, tying a bow-knot, and repeating digits. 
 
 Summary 
 
 1. The tests indicate a slight superiority of girls 
 over boys at each age from 5 to 13. The apparent 
 superiority of the boys at 14, however, is probably 
 accounted for by the unequal selection which has taken 
 place m the promotion of pupils to the high school. 
 
 2. The small superiority of the girls in the tests 
 probably rests upon a real superiority in intelUgence, 
 age for age. At least, this conclusion is supported 
 by the age-grade distribution of the sexes, and by 
 the teachers' rankings according to intelhgence and 
 quality of school work. 
 
 3. Apart from the small superiority of the girls, 
 the distribution of intelUgence shows no significant 
 difference in the sexes. The data offer no support 
 to the wide-spread belief that gMs group themselves 
 more closely about the median or that extremes of 
 intelligence are more common among boys. 
 
 4. Not many of the individual tests show large 
 sex differences in the percent passing in three con- 
 secutive years. In certain of the tests, however, 
 the differences were marked and unexpected. 
 
CHAPTER V 
 
 THE RELATION OF INTELLIGENCE TO 
 SOCIAL STATUS 
 
 In the use of the Bmet scale with different social 
 classes it has generally been found that children who 
 come from superior environment test higher than those 
 who come from homes where the degree of cidture 
 is inferior. As already noted, the arrangement of 
 tests in the 1908 Binet scale was based on an exami- 
 nation of about 200 children from one of the poorest 
 quarters of Paris. When the scale thus derived was 
 ' used by Decroly and Degand in the examination of 
 children from wealthy and cultured homes, in a Brus- 
 sels private school, it was found that many of the 
 tests were passed two years below the location assigned 
 them by Binet. Jeronutti's tests of 144 better-class 
 children of Rome agree closely with those of Decroly 
 and Degand. The same is true of Madame Wolk- 
 owitsch's tests of private-school children at Petrograd. 
 On the other hand. Dr. Anna Schubert's data gathered 
 from 229 lower-class children in a Moscow orphanage 
 gave a distribution of mental ages skewed in the 
 opposite direction. In fact, none of Dr. Schubert's 
 children were advanced more than one year, only 
 27 percent tested "at age," while 75 percent were 
 retarded one year or more and 39 percent two years 
 or more. 
 
 Binet, himself, took up the question by having 
 tests made of 54 children who had been classified into 
 four groups by the teachers according to social status. 
 Unfortunately, the school chosen was one which was 
 
 84 
 
EELATION OF INTELLIGENCE TO SOCIAL STATUS 85 
 
 not attended by children of the highest social classes, 
 and the number tested was very small. The results 
 failed to show any correlation of mental age with 
 social status. A later comparison by Binet of 30 
 children attending a poorly situated school with 30 
 others attending a school in a well-to-do neighborhood 
 of Paris showed a marked difference in favor of the 
 better situated children. 
 
 The Breslau experiment, of which a partial account 
 has been given by Stern,' indicated that pupils of 
 the Volksschule are at the age of 10 years somewhere 
 near the level of mental development which is at- 
 tained by pupils of the Vorschule at 9 years. The 
 Volksschulen are attended mainly by children of the 
 laboring and lower business classes and the Vorschulen 
 by children of the better classes. Likewise, in com- 
 paring children of the upper and lower social classes 
 in Enghsh infant schools. Winch found the children 
 of the higher class superior to the other group in a 
 majority of the tests. 
 
 Study of the data which we have collated for the 
 individual tests of the scale shows that large differ- 
 ences found by investigators in the percentage of 
 children who pass certain tests may often be accounted 
 for by a difference in the social class of the subjects. 
 
 Yerkes and Bridges compared 54 pupils of a better- 
 class school with an equal number attending a poor 
 school. The sexes were represented equally, and the 
 pupils were selected in such a way that a boy or girl 
 of the favored group was matched by a boy or girl 
 of approximately the same age from the unfavored 
 group. The comparison showed that by the Yerkes- 
 
 * The Psychological Methods of Testing Intelligence, These Mono- 
 QHAPH8, No. 13, 1914, pp. 54 ff. 
 
86 STANFORD REVISION OF BINET-SIMON SCALE 
 
 Bridges scale the favored boys averaged 7.7 points 
 higher and the girls 8.4 points higher than did the 
 members of the unfavored group of the- same ages. 
 If we compare this difference in points with the age- 
 norms given by Yerkes and Bridges, we find that it 
 represents about a year of difference in mental ad- 
 vancement with children of this age. Binet at one 
 time estimated that social status might make as much 
 as a year and a-haK difference in mental age, though 
 in making this statement he seems to have overlooked 
 the fact that a retardation of a year and a-half is not 
 of equal significance in the lower and upper ages. 
 
 The tacit assumption which most writers seem to 
 have made in their discussions of such facts as those 
 we have just set forth is that the difference found is 
 due wholly, or at least mainly, to the influence of 
 environment. Meumann beUeves that the most seri- 
 ous fault of the Binet scale is its failure to take account 
 of the influence of social environment on the ability 
 to pass certain tests. Yerkes and Bridges assert 
 that "it is obviously unfair to judge by the same norm 
 of intelHgence two children, the one of whom comes 
 from an excellent home and neighborhood, the other 
 from a medium-to-poor home and neighborhood." 
 
 As will be shown presently, we beheve that the 
 facts may be more reasonably explained on an entirely 
 different hypothesis. First, however, we will set 
 forth somewhat in detail the Stanford data that bear 
 upon this question. 
 
 As stated elsewhere, we were able to secure a classi- 
 fication of 492 of our children according to social 
 class into five groups: "very inferior," "inferior," 
 "average," "superior" and very superior." Although 
 the schools chosen for the tests were on the whole 
 
RELATION OF INTELLIGENCE TO SOCIAL STATUS 87 
 
 as nearly average as could be found, it will be readily 
 understood by anyone who is acquainted with thei 
 democracy of the American educational system that/ 
 in almost any small city an "average" school contains' 
 some children of every social class. As was expected, 
 therefore, all the social classes were found to be rep- 
 resented in every school. Graph 38 shows the dis- 
 tribution by social class of the 492 children regarding 
 whom the supplementary information was obtained. 
 
 Vtrjf Inferior Inferior A\/tra^e Superior i/ery Superior- 
 
 Z'l. /B.67. S&57. 20.6y. /.G'/. 
 
 Graph 38. The Distribution by Social Class op 492 Children 
 OP All Ages. 
 
 We have next classified these same pupils according 
 to the intelligence quotients resulting from the tests, 
 and for tliis purpose also we have made use of five 
 groups, as follows: 
 
 I Q 120 or 
 IQ below 80 I Q 80-89 I Q 90-109 1 Q 110-119 above 
 
 "Veryinfe- "Very 
 
 rior" "Inferior" "Average" "Superior" superior" 
 
88 STANFORD REVISION OF BINET-SIMON SCALE 
 
 This grouping of the intelligence quotients is, of 
 course, arbitrary, but some sort of grouping is neces- 
 sary, and the one we have employed has the advantage 
 of giving five groups of intelligence quotients which 
 agree roughly in size with the groups according to 
 social class. This correspondence is as follows: 
 
 TABLE 22 
 Percent of Pupils in Each Gboitp 
 
 IQ I Q below 80 I Q 80-89 I Q 90-109 IQ 110-119 I Q 120 or above 
 
 6.9 14.5 57.7 15 5,6 
 
 Social 
 
 Very 
 
 
 
 
 Very 
 
 Status 
 
 inferior 
 
 Inferior 
 
 Average 
 
 Superior 
 
 Buperior 
 
 
 2 
 
 16.6 
 
 56.5 
 
 20.6 
 
 1.6 
 
 Table 23 shows where the children in each social 
 group fall with reference to intelligence quotient, and 
 also where those of any intelligence quotient group 
 fall with reference to social class. 
 
 TABLE 23 
 The Relation op Intelligence to Social Stattts 
 
 
 
 
 1 Q 
 
 
 
 
 Social 
 
 
 
 
 
 120 or 
 
 
 Status 
 
 Below 80 
 
 81-89 
 
 90-109 
 
 110-119 
 
 above 
 
 Total 
 
 Very 
 Inferior 
 
 4 
 
 4 
 
 3 
 
 
 
 
 
 11 
 
 Inferior 
 
 18 
 
 15 
 
 43 
 
 4 
 
 
 
 102 
 
 Average 
 
 9 
 
 43 
 
 181 
 
 48 
 
 11 
 
 292 
 
 Superior 
 
 1 
 
 7 
 
 59 
 
 21 
 
 14 
 
 80 
 
 Very 
 Superior 
 
 
 
 
 
 3 
 
 2 
 
 2 
 
 7 
 
 Total 
 
 32 
 
 69 
 
 289 
 
 75 
 
 27 
 
 492 
 
EELATION OF INTELLIGENCE TO SOCIAL STATUS 89 
 
 That there is a certain degree of correlation between 
 intelligence quotient and social status is quite evident 
 from a glance at the table. Of the 27 children with an 
 intelligence quotient of 120 or above, not a single 
 one comes from a social class below the average; of 
 the 75 with an intelligence quotient between 110 and 
 119, only 4 belong to the "inferior" social group, and 
 none to the "very inferior group." Conversely, of 
 the 32 children with an intelligence quotient below 80, 
 only one is classified below the "average" social group. 
 Only the middle intelUgence quotient group, 90-109, 
 is represented in all the social classes; and only the 
 "average" and "superior" social group is represented 
 in aU the inteUigence quotient groups. AppUcation 
 of the Pearson formula to the data in this table gives 
 a correlation of .40 between social status and intelli- 
 gence quotient. 
 
 Another way to express the relationship between 
 intelUgence and social status is to compare the median 
 inteUigence quotient for the chUdren of each social 
 group, as follows: 
 
 Social Group Very Inferior Inferior Average Superior Very Superior 
 Median I Q 85 93 99.5 107 106 
 
 Since only 8 pupils are included in the "very in- 
 ferior" and only 10 in the "very superior" social 
 groups, the medians for these extreme groups have 
 limited significance. The case is different, however, 
 ia the "inferior," "average" and "superior" groups, 
 which include 80, 292, and 102 cases, respectively. 
 
 Graphs 39, 40, and 41 show the distribution of 
 iatelUgence quotients grouped by lO's for the three 
 social classes. In this case the 7 "very inferior" 
 pupils are thrown with the "inferior" class, and the 
 11 "very superior" pupUs with the "superior" class. 
 
90 STANFORD REVISION OF BINET-SIMON SCALE 
 
 S6-&S &6-7S r&SS 3&-9S 3& -lOS lOb-llS II&-IZ5 IZe>-l3S I3l3-li 
 ^ 3.8% <5.6% Z8.S)'. 4-2.1. 3SK 7.i>% J 
 
 cJl.OisTr-ibuTion af I Q's of t05 t-hildre-n of Superior ond'vtry suptrioA 
 
 j>ot.i'el elofisti. < 
 
 S&-.Gf (,G-7S 7&-8S 8e>-9S Sb-IOS IOb-115 llb-IZS tZ.B-l3SI3b-h 
 /•/. &f'l. Z^.b'lo -37% Z0% 8.11 .H. &h 
 ^O.Qj^Tri buTl'on of I Q's of 285^ children of " averaje." s-ociol <.loii. 
 
 SG-b5 i>b-75 7lo-8S SG -Sr 56 -/OS lOi, -//i" //6 -IZSIZ 6 -135 13(> '/^ 
 f'/. ir/c /8.&'/, ZZ.1% 30.37, 8.1% Z.37o 
 ^ffj, Oifi-Tribution of I Qs of 8& children of'inferior" and "i^ery inf trier' 
 
RELATION OF INTELLIGENCE TO SOCIAL STATUS 91 
 
 The median intelligence quotient of the "average" 
 social group is 99.5, and so practically coincides with 
 the median for all classes taken together. It is sig- 
 nificant that the median intelligence quotient of the 
 "inferior" group is 14 points below that of the "superior" 
 group, and that the median intelligence quotient for the 
 "average" group Ues approximately mid-way between 
 the two. The difference between the median intelli- 
 gence quotients of the "inferior" and the "superior" 
 groups means a difference in mental age at the various 
 actual ages as follows: 
 
 TABLE 24 
 Median Difference in Mental Age 
 Age Age 
 
 4 6.7 mo. 10 16.8 mo. 
 
 5 8.4 " 11 18.5 
 
 6 10.1 " 12 20.2 
 
 7 11.7 " 13 21.8 
 
 8 13.4 " 14 23.5 
 
 9 15.1 " 15 25.2 
 
 Our results, accordingly, agree closely with those 
 of other workers. Our next task is to find the most 
 rational hypothesis which will explain J^he ^ corre lation 
 between social status and intelligence quotient. 
 
 The usual assumption has been that the correlation 
 is the artificial product of environmental influences; 
 that the child from a cultured home does better in the 
 tests by reason of his superior home training and because 
 he has had more opportunity to pick up the informa- 
 tion which success in the various tests calls for. This 
 explanation has seemed to us from the beginning a 
 most improbable one. Several investigations of the 
 influence of environment on mental traits suggest 
 the conclusion that this influence is much less important 
 than is original endowment in determining the nature 
 
92 STANFORD REVISION Or BINET-SIMON SCALE 
 
 of the traits in question. From an a-priori stand- 
 point, the endowment hypothesis explains the correla- 
 tion between intelligence quotient and social status 
 just as adequately as does the environment hypothesis. 
 To conclude, as Meumann and Yerkes have done, 
 that the demonstration of the existence of such a 
 correlation invaUdates the Binet scale as a method 
 of measuring intelligence is to make a gratuitous 
 assumption — ^an assumption, indeed, which is con- 
 tradicted by much evidence from investigations bearing 
 on the mental endowment of different social groups. 
 We have thought it worth while, therefore, to sift 
 our data somewhat carefully for evidence on this 
 point. 
 
 First, we have compared the social status of the 
 children with the teachers' estimates of intelUgence. 
 The tests themselves are brief. Success in some of 
 them, it must be admitted, hinges upon information, 
 the possession of which might conceivably be largely 
 conditioned by home environment. One thinks ia 
 this connection of such tests as naming coins, making 
 change, repeating the days of the week and the month 
 of the year, giving definitions, giving the moral of 
 fables, etc. Success in certain others would appear 
 to depend rather too much on facility in the use of 
 language. But the teacher's judgment as to a child's 
 intelligence is based upon months of acquaintance, in 
 this case from half to an entire school year. The 
 teacher has had abundant opportunity to distinguish 
 between real mental ability on the one hand and the 
 accidents of knowledge, or facility in the use of langu- 
 age, on the other. Accordingly, Table 25, which 
 gives the teacher's judgment as to the intelligence of 
 each child in the various social groups, should be of 
 interest. 
 
KBLATION OP INTELLIGENCE TO SOCIAL STATUS 93 
 
 TABLE 25 
 
 The Intelligence op Children op Various Social Classes as 
 Estimated bt the Teachers 
 
 
 
 Teachers' Estimate of Intelligence 
 
 
 Social 
 Status 
 
 Very- 
 Inferior 
 
 Inferior 
 
 Average 
 
 Superior 
 
 Very 
 Superior 
 
 Total 
 
 Very 
 Inferior 
 
 6 
 
 2 
 
 3 
 
 
 
 
 
 11 
 
 Inferior 
 
 4 
 
 31 
 
 36 
 
 s 
 
 1 
 
 77 
 
 Average 
 
 7 
 
 34 
 
 93 
 
 50 
 
 4 
 
 188 
 
 Superior 
 
 1 
 
 
 
 40 
 
 56 
 
 4 
 
 101 
 
 Very 
 Superior 
 
 
 
 
 
 
 
 2 
 
 6 
 
 8 
 
 Total 
 
 18 
 
 67 
 
 172 
 
 113 
 
 15 
 
 385 
 
 Casual inspection of this table shows that the judg- 
 ment of the teachers accords with the evidence from 
 the tests in crediting greater mental abihty to the 
 children of superior social status. Not one of the 
 children of the "very superior" social group is ranked 
 below "superior" intelligence, and of the 101 included 
 in the "superior" social group only one falls below 
 "average" intelligence. Conversely, not one of the 
 11 children of "very inferior" social status ranks above 
 "average" in intelligence, while 6 of them are classified 
 as intellectually "very inferior." By the Pearson N 
 formula the correlation between social status and the \ 
 teachers' estimates of intelligence is .55. This is \ 
 considerably higher than the .40 correlation found J 
 between social status and intelligence quotient. 
 
 But children from superior homes are likely to be 
 better dressed, cleaner and more attractive in appear- 
 ance than children from the poorer homes. Perhaps, 
 
94 STANFORD REVISION OF BINET-SIMON SCALE 
 
 too, they are better behaved, more responsive, and 
 socially more adaptable on account of superior training 
 in the home. It is conceivable that external appear- 
 ances of this kind, which, all would agree, are in part 
 an expression of home conditions, have deceived the 
 teachers and influenced their ranking of the children 
 according to intelligence. 
 
 If this were true, the actual quality of the school 
 work done by the children of various social groups 
 might be expected to afford a corrective for this possible 
 error. School work, because it is more definite and 
 objective, is easier to judge than the complex of mental 
 traits called intelUgence. Table 26 shows the quality 
 of the school work, as judged by the teachers, for all 
 the children of the several social groups. 
 
 
 
 TABLE 26 
 
 
 
 
 The Qttalitt op School Wobk Done by Chtt.dren of the 
 Social Groups 
 
 Various 
 
 
 
 QUALITY OF School Work 
 
 
 Social 
 
 Verj' 
 
 
 
 
 Very 
 
 
 Status 
 
 Inferior 
 
 Inferior 
 
 Average 
 
 Superior 
 
 Superior 
 
 Total 
 
 Very 
 Inferior 
 
 S 
 
 4 
 
 3 
 
 
 
 
 
 12 
 
 Inferior 
 
 10 
 
 29 
 
 35 
 
 6 
 
 2 
 
 82 
 
 Average 
 
 9 
 
 52 
 
 160 
 
 60 
 
 4 
 
 285 
 
 Superior 
 
 
 
 4 
 
 51 
 
 46 
 
 4 
 
 105 
 
 Very 
 Superior 
 
 
 
 
 
 
 
 2 
 
 6 
 
 8 
 
 Total 
 
 24 
 
 89 
 
 249 
 
 114 
 
 16 
 
 492 
 
 By the Pearson formula the correlation expressed 
 in this table amounts to .47, which is only a little 
 lower than that found for the teachers' estimates and 
 
RELATION OF INTELLIGENCE TO SOCIAL STATUS 95 
 
 social status, and somewhat higher than that between 
 social status and intelligence quotient. 
 
 We would attach especial importance to this correla- 
 tion, for the reason that the wide-spread use of peda- 
 gogical tests in recent years has demonstrated that 
 the indiAddual differences in subject-proficiency which 
 such tests bring to light among school children repre- 
 sent, in large part, individual differences in . native 
 ^ndow inent and not the effects of unequal home or 
 school training. Even spelling abihty, contrary to 
 common opinion, is largely a function of general intelli- 
 gence. As Mr. Houser has shown, the correlation 
 between the two ranges from 35 to 71 percent.^ In- 
 dividual instruction, "special class" methods, indeed, 
 the concentrated efforts of an entire school system, 
 are unable to wipe out the major differences of this 
 kind in a dozen years. As a rule, the longer the child 
 is in school, the more evident the inferiority of the 
 inferior child becomes. It would hardly be reason- 
 able, therefore, to expect that a little incidental experi- 
 ence and instruction in the home, amounting perhaps 
 in most cases to not more than a few minutes per day, 
 would weigh very heavily against these native differ- 
 ences. Even in good homes, children are likely to 
 learn less from their parents than from their play 
 fellows and nurses. 
 
 For further evidence on the relation of school success 
 to social status, we will examine the age-grade dis- 
 tribution of the children in the five social groups. 
 This is shown in Table 27 for the ages 8-16. Children 
 below 8 were omitted from this comparison because 
 
 'See J. D. Houser: "The relation of ability to general intelligence 
 and to meaning vocabulary. The Elementary School Journal, Deo., 
 1915. 
 
96 STANFORD REVISION OF BINET-SIMON SCALE 
 
 Kh 
 
 
 
 
 TABLE 27 
 
 
 
 
 
 The Relation of Age-grade Distribution to Social Status 
 
 
 Location in the Grades 
 
 Social 
 
 Status 
 
 Retarded 
 
 In 
 
 Advanced 
 
 
 
 
 
 Grade 
 
 
 
 
 
 
 4 yr. 
 
 Syr. 
 
 2 yr. 
 
 lyr. 
 
 for Age 
 
 lyr. 
 
 2yr. 
 
 3yr. 
 
 Total 
 
 Very 
 Inferior 
 
 1 
 
 1 
 
 2 
 
 2 
 
 2 
 
 
 
 
 8 
 
 Inferior 
 
 3 
 
 4 
 
 10 
 
 27 
 
 11 
 
 4 
 
 
 
 59 
 
 Average 
 
 1 
 
 4 
 
 21 
 
 66 
 
 109 
 
 21 
 
 2 
 
 
 224 
 
 Superior 
 
 
 
 4 
 
 16 
 
 30 
 
 14 
 
 
 
 64 
 
 Very 
 Superior 
 
 
 
 
 3 
 
 2 
 
 1 
 
 
 
 6 
 
 Total 
 
 S 
 
 9 
 
 37 
 
 114 
 
 154 
 
 40 
 
 2 
 
 
 321 
 
 they have not had time to become much retarded or 
 accelerated in school. Normal progress is here defined 
 as Grade II at Age 8, Grade III at Age 9, etc. 
 
 The correlation here is positive, but somewhat 
 snmller than in the case of the intelligence quotient, 
 the teachers' estimates of intelligence, and the quality 
 of the school work. This is what we should expect, 
 knowing that the tendency of schools is to promote 
 children by age rather than by quaUty of school work 
 or native ability. 
 
 Again, if home environment really has any con- 
 siderable effect upon the intelligence quotient we 
 should expect this effect to become more marked, the 
 longer the influence has continued. That is, the 
 / correlation of intelligence quotient with social status 
 should increase with age. We have accordingly 
 
RELATION OF INTELLIGENCE TO SOCIAL STATUS 97 
 
 worked out the correlation between intelligence quo- 
 tient and social status for three separate age-levels: 
 for Years 5, 6, 7 and 8 taken together; for 9, 10, and 11 
 combined; and for 12, 13, 14, and 15 likewise combined. 
 The coefficients of correlation for these three age- 
 levels were, respectively, .43, .41, and .29. In other 
 words, the longer the supposed powerful influence of 
 home environment is continued, the more independent 
 of it the intelligence quotient becomes. The con^ 
 elusion indicated is that the home environment, a; 
 environment, has in all ages of childhood relatively 
 little weight in determining the intelligence quotient 
 One other line of argument remains. Anyone who' 
 has done much testing knows that if sufficiently large 
 numbers are taken, every degree of intelligence from^i 
 profound idiocy to very superior abiUty is. represented! 
 in every social class. This did not happen to be true 
 in the case of our 500 non-selected children from whom 
 supplementary data were available, but we may be 
 certain that it would have been true if a hundred or a 
 thousand times as many children had been tested. 
 In miscellaneous testing, the data from which are 
 not included in the present study of non-selected 
 children, we have found two children of extraordinarily 
 poor home environment who had an intelhgence 
 quotient of 150. The highest we have ever found 
 among children of any class is 170. It is a common- 
 place that dull and feeble-minded children of all grades 
 of deficiency may be found in any social class. We 
 have tested two feeble-minded children whose fathers 
 were men of substantial reputation for scientific 
 achievement. It goes without saying that in each 
 case the home environment was everything that could 
 have been desired. In each family there are other 
 
 7 
 
98 STANFORD REVISION OF BINET-SIMON SCALE 
 
 children whose inteUigence quotients range from 115 
 to 125. Three children were tested in another family, 
 in which the home conditions were about as wretched 
 as could be imagined. Two of these children had an 
 intelligence quotient between 75 and 85, the third 
 an intelligence quotient of 120. The two former have 
 since shown their inability to do fifth-grade school 
 work by the age of 15 years, while the latter entered 
 the high school at the age of 12. Since the unfavorable 
 home environment did not prevent the superior endow- 
 ment of the one child from evidencing itself in the 
 tests, we must conclude that the inferior showing 
 of the other two could have not been caused by this 
 same environment. 
 
 These are individual cases, and we would not stress 
 them unduly. They do illustrate, however, a most 
 important fact, — that exceptionally superior endow- 
 ment is discovered by the tests, however unfavorable 
 the home from which it comes, and that inferior men- 
 tality can not be overcome by all the advantages of 
 the most cultured home. 
 
 Of course, we would not deny all possibility of 
 environmental conditions affecting the result of an 
 intelligence test. On the contrary, we have no doubt 
 that the influence is always present in some degree. 
 What it accounts for in terms of the intelligence 
 quotient, we do not know. That it accounts for the 
 larger and more significant differences seems to us 
 wholly improbable. We have little reason to believe 
 that ordinary differences in social environment (apart 
 from heredity) — differences such as those obtaining 
 between the higher and lower classes of children 
 attending approximately the same general type of 
 school in a civilized community — impair the validity 
 of the scale to any great extent. 
 
RELATION OF INTELLIGENCE TO SOCIAL STATUS 99 
 
 A crucial experiment would be to take a large number 
 of young children of the lower classes and, after placing 
 them in the most favorable environment obtainable, 
 to compare their later mental development with that 
 of children born into the best homes. No such study, 
 properly safe-guarded, seems to have been made. 
 The study would be quite feasible if carried out with 
 the cooperation of a well-conducted orphanage. Some 
 of the tests which have been made in such institutions 
 indicate that mental subnormality of both high and 
 moderate grades is extremely frequent among children 
 who are placed in these homes. Most, though ad- 
 mittedly not all of them, are children of inferior social 
 classes. 
 
 Of 20 orphanage children tested by the writer only 3 
 were fully normal. The other 17 ranged in intelUgence 
 quotient from 75 to 95. Nearly all of these children 
 ^had been in the orphanage for from two to several 
 years. The orphanage in question is a reasonably 
 good one and affords an environment which is about 
 as stimulating to normal mental development as 
 average home life among the middle classes. The 
 children live in the orphanage and attend an excellent 
 public school in a California village.^ 
 
 After all, does not common observation teach us 
 that, in the main, native qualities of intellect and 
 character, rather than chance, determine the social 
 class to which a family belongs? From what is already 
 known about heredity should we not naturally expect 
 to find the children of well-to-do, cultured, and success- 
 ful parents better endowed than the children who have 
 been reared in slums and poverty? An affirmative 
 
 ' Additional data will be published shortly on the influence of orphan- 
 age life on the intelligence quotient of children who have come from 
 low-grade homes. 
 
100 STANFORD REVISION OF BINET-SIMON SCALE 
 
 answer to the above question is suggested by nearly 
 all the available scientific evidence. The suggestion 
 urged by Meumann and also by Yerkes, that it is 
 unfair to evaluate the intelligence of any child except 
 in terms of the average intelUgence of his own social 
 class, is not warranted. It would be just as logical 
 to insist that it is unfair to the dull or feeble-minded 
 child to judge his intelUgence with reference to standard 
 intelhgence for the mentally normal. 
 
 Finally, it should be pointed out that Meumann's 
 strictures on the Binet scale in this connection had 
 their origin in certain discrepancies observed in the 
 results of various investigators, which seemed to him 
 attributable entirely to differences in the social status 
 of the subjects tested. It can be shown, however, 
 that the observed discrepancies may be largely ac- 
 counted for in other ways. They may have resulted 
 in part from failure to follow the same procedure in 
 giving or scoring the tests. Experience in training 
 a fairly large number of individuals in the correct 
 use of the Binet method leads one to stress this factor 
 as a possible source of large discrepancies in results. 
 Moreover, closer inspection of the discrepancies shows 
 that they are much smaller than Meumann seems to 
 have estimated them. As a criterion of agreement 
 between two workers he uses the relative percentages 
 of children found to test "at age," +1, +2, — 1, — 2, 
 etc. In certain cases, this criterion has been mis- 
 leading. It is well known that the original Binet 
 scale was much too easy at the lower end and much 
 too difficult at the upper. Accordingly, whether the 
 mental ages found by a given worker turn out to be 
 predominantly plus or predominantly minus depends 
 largely on the age of the subjects. If these are young, 
 
RELATION OF INTELLIGENCE TO SOCIAL STATUS 101 
 
 the mental ages, by the original Binet scale, will tend 
 to run too high. If they have reached an age which 
 demands the use of the upper tests, the resulting 
 mental ages will be too low. Meumann instances 
 the high mental ages found by Jeronutti in his tests 
 of better-class children in Rome as evidence purely 
 of the influence of milieu. However, an examination 
 of Jeronutti's table of results by ages reveals the fact 
 that the excess of plus mental ages is present only 
 in the years below 10. Above 10, the mental ages 
 fall predominantly on the minus side. Meumann 
 seems to have been similarly misled with reference 
 to the high mental ages found by Madame Wolko- 
 witsch at Petrograd. Since her children were of 
 kindergarten age, we may be sure that their high 
 mental ages resulted in part from the incorrectness 
 of the scale at this point and only in part from the 
 high social status of the children. On the other hand, 
 Meumann instances the excess of minus mental ages 
 found in Miss Johnston's tests as an example of the 
 unfavorable influence of low social status on test 
 performance. The fact is that Miss Johnston's excess 
 of minus mental ages occurs most noticeably in the 
 years above 9, where the scale is demonstrably too 
 hard. Of her 7-year-olds, only 5 tested minus and 
 24 at or above age. 
 
 We would agree with Stem that the remarkable 
 fact is not that minor discrepancies have appeared 
 in the statistics of different workers, but that their 
 results, gathered in France, England, Germany, Russia, 
 Italy, Belgium and diverse parts of the United States, 
 from different classes of children and by methods 
 which have undoubtedly fallen short of the desired 
 uniformity, should agree as closely as they do. 
 
102 STANFORD REVISION OF BINET-SIMON SCALE 
 
 It is quite possible that some of the individual tests 
 of the Binet scale are affected by accidents of environ- 
 ment and training to an extent which largely invali- 
 dates them as measures of inteUigence. We do not 
 know which tests are included in this class, but re- 
 search will ultimately disclose their identity. Kuhl- 
 mann has shown how unsafe it is to condemn a test 
 off-hand as subject to this or that disturbing influence.* 
 The classification of the tests in Meumann's three-fold 
 test series (tests of maturity, tests of endowment, and 
 tests of milieu) is based upon inspection, and has little 
 value beyond the program of research which it sug- 
 gests, i" 
 
 To ascertain the extent to which a test is influenced 
 by environment, apart from endowment, is not easy. 
 I An attempt was made to analyze the Stanford data 
 (for evidence of this influence on the individual tests, 
 but it was abandoned. Qf the 80 to 120 children at 
 each age from 10 to 15 were ordinarily found in each 
 of the two social classes "inferior" and "superior." 
 Such numbers are at best too small to have statistical 
 value, and in this case the matter was further com- 
 plicated by the presence of large differences due 
 presumably to native endowment. To all appear- 
 ances, the average child of any social class behaved 
 in the tests like a child of any other class who had the 
 same intelligence level. 
 
 *F. Kuhlmann; The Binet-Simon testa in grading feeble-minded 
 children, J. of Psycho-Asthenics, XVI, 1912, pp. 173-193. 
 
 ' See Terman's review of Meumann on the Psychology of Endow- 
 ment, J. of Psych.-Asthenics, 14: 1914-1915; pp. 75-94; 123-134; and 
 187-199. 
 
RELATION OF INTELLIGENCE TO SOCIAL STATUS 103 
 
 Summary 
 
 1. The median intelligence quotient for children 
 of the superior social class is about 7 points above, 
 and that of the inferior social class about 7 points 
 below the median intelligence quotient of the average 
 social group. This means that by the age of 14, 
 inferior-class children are about one year below, and 
 superior-class children about one year above, the 
 median mental age for all classes taken together. 
 
 2. That the children of the superior social classes 
 do better in the tests is almost certainly due primarily 
 to superior original endowment. This conclusion is 
 supported by five supplementary lines of evidence: 
 (a) the teachers' rankings of the children according 
 to intelligence, (6) the age-grade progress of the chil- 
 dren, (c) the quality of the school work, (d) the com- 
 parison of older and younger children as regards the 
 influence of social environment, (e) the study of 
 individual cases of bright and dull children in the same 
 family. 
 
 3. In order to facilitate comparison, it is advisable 
 to express the intelligence of children of all social 
 classes in terms of the same objective scale of intelli- 
 gence. This scale should be based on the median 
 for all classes taken together. 
 
 4. Meumann's criticism of the scale with reference 
 to the influence of social environment on the test 
 results was based on insufficient examination of the 
 data, particularly on the failure to take account of the 
 prevailing ages of the children tested in different 
 investigations. 
 
 5. In their responses to individual tests, our children 
 of a given social class were not distinguishable from 
 children of the same intelligence level in any other 
 social class. 
 
CHAPTER VI 
 
 The Relation of Intelligence to School Success 
 
 The degree of school success offers a partial check 
 on the accuracy of the intelligence scale. While we 
 should not expect complete agreement between scholar- 
 ship and the results of even a perfect test of intelUgence, 
 nevertheless a very marked disagreement between 
 the two would suggest some fault either in the tests 
 or in the method of estimating school success. 
 
 There are three main indices of the degree of school 
 success which a given child has attained: (1) his 
 advancement in the school grades, (2) the quality 
 of school work he is doing in the grade where he is 
 enrolled, and (3) the extent to which he is regarded 
 by the teacher as intelligent. 
 
 At first thought the last point may seem irrelevant. 
 We are taking the term "school success," however, 
 in an inclusive sense. In estimating an individual's 
 success in life we ordinarily take into account not only 
 the objective record of his achievements, but also the 
 impression he has made on his associates and superiors. 
 The latter is a real part of his success. For our present 
 purpose it is important to know whether a child whose 
 intelUgence is judged by the teacher to be "inferior" 
 is really capable of doing "superior" school work; 
 or conversely, whether a child judged by the teacher 
 as of "superior" intelligence is likely to do "inferior" 
 school work. 
 
 104 
 
RELATION OF INTELLIGENCE TO SCHOOL SUCCESS 105 
 
 Comparison of Intelligence Quotient with the Quality of 
 
 the School Work as Judged by 
 
 the Teachers 
 
 Table 28 shows the teachers' judgments as to the 
 quaUty of school work done by children of the intelU- 
 gence quotient groups below 80, 80-89, 90-109, 110- 
 119, and 120 or above. 
 
 TABLE 28 
 
 The Relation Between Intelligence Quotient and Quality op 
 School Work (as Judged bt the Teachers) 
 
 Quality of 
 
 Intelligence quotients 
 
 School Work 
 
 
 
 
 
 
 
 
 Below 80 
 
 89-89 
 
 90-109 
 
 110-119 
 
 120-above 
 
 Total 
 
 Very 
 Inferior 
 
 12 
 
 5 
 
 8 
 
 
 
 
 
 25 
 
 Inferior 
 
 9 
 
 28 
 
 49 
 
 6 
 
 
 
 92 
 
 Average 
 
 8 
 
 34 
 
 173 
 
 32 
 
 10 
 
 257 
 
 Superior 
 
 1 
 
 5 
 
 60 
 
 32 
 
 15 
 
 113 
 
 Very 
 Superior 
 
 
 
 
 
 12 
 
 3 
 
 2 
 
 17 
 
 Total 
 
 30 
 
 72 
 
 302 
 
 73 
 
 27 
 
 504 
 
 It is evident from the table that a fairly high correla- 
 tion is present. No child doing "very superior" school 
 work has an intelligence quotient below the middle 
 group 90-109, and no child doing "very inferior" work 
 ranks in mtelligence quotient above the middle group. 
 The agreement, however, is far from perfect. The 
 group doing "average" school work contains intelligence 
 quotients all the way from "below 80" to "120 or 
 above." One child with an intelligence quotient below 
 
106 STANFOKD REVISION OF BINET-SIMON SCALE 
 
 80 is ranked as doing "superior" school work. The 
 correlation by the Pearson formula is .45. 
 
 There are 51 cases out of a total of 504 in which 
 the quality of the school work is two steps removed 
 from the location required for perfect correlation. 
 This is nearly 10 percent of all. An occasional dis- 
 agreement of one step would naturally be expected, 
 since we know that the quality of school work depends 
 partly on factors other than intelligence, such as 
 health, industry, conscientiousness, quality of teach- 
 ing, etc. But a disagreement of two steps is serious. 
 
 We have examined our data to see if any evidence 
 could be found of the presence of constant factors tend- 
 ing to explain the disagreement between intelUgence 
 quotient and quality of school work. In the table are 
 26 children whose school work is at least two grades 
 better than the intelligence quotient would itself 
 warrant. On looking up the facts about these children, 
 we find that 19 of them are over-age for their grade. 
 Of these, 10 are from two to four years over-age. Of 
 course nothing else is needed to explain the disagree- 
 ment in these cases. We know it to be true that a 
 10-year-old child with a mental age of 8 years (intelli- 
 gence quotient 80) is usually just about able to do 
 school work of average quality in the second grade, 
 or that a 13-year-old with a mental age of 10 years 
 (intelligence quotient 77) can manage to get along 
 fairly well in the third or fourth grade. 
 
 Of the other cases of disagreement in this direction, 
 4 were kindergarten children. Perhaps these should 
 be thrown out altogether, on the ground that the work 
 of the kindergarten fails to bring out clearly differences 
 of intelligence. Of the remaining cases, one girl of 
 8 years was described by the teacher as "very timid 
 
RELATION OF INTELLIGENCE TO SCHOOL SUCCESS 107 
 
 and sensitive," and it is possible that this caused an 
 unfavorable showing in the tests. Another, also a 
 girl, was described as a child of "wonderfully sweet 
 disposition," that is, the kind of child we are always 
 ready to give the benefit of a doubt. In two other 
 cases there was an additional explanation, namely, 
 an intelligence quotient which was just over the border 
 between two groups. If one of these had tested at 
 90 instead of 89, and the other at 110 instead of 109, 
 one step of the disagreement would have been elimi- 
 nated. Accordingly, we may say that of the 26 cases 
 of serious disagreement, 19 are largely accounted for 
 by over-ageness, 4 by the fact that the school attended 
 was a kindergarten which has no formal work, and that 
 in only 2 of the 26 cases was no explanation suggested 
 by the data at hand. 
 
 We will now consider the 24 children the quality 
 of whose school work ranked two grades below what 
 the intelligence quotient would lead us to expect. 
 Since over-ageness accounted for nearly two-thirds of 
 the disagreements ia the other direction, we will nat- 
 urally expect to find under-ageness a frequent cause 
 of displacement downward. This is true, but to a 
 less extent than one might have expected. Of the 24 
 children, 10, or nearly 40 percent, are under-age for 
 the grade they are in. Seven of these, however, are 
 only one year advanced beyond age, a degree of under- 
 ageness which would hardly account for more than 
 half of the observed disagreement in these cases. 
 Four others are kindergarten children and so may be 
 left out of account. In one other case the teacher 
 had contradicted herself. The child in question had 
 an inteUigence quotient of 125 but had been ranked 
 only "average" in school work. The teacher's supple- 
 
108 STANFORD REVISION OF BINET-SIMON SCALE 
 
 mentary statement, however, showed that the marks 
 ranged from B to A in every subject except arith- 
 metic, and other statements indicated that the child 
 had unusual talent in composition and in the apprecia- 
 tion of literature. Two cases were sufficiently ex- 
 plained by illness and long absence from school. An- 
 other child was described as lazy and incorrigible — 
 traits which would affect the school work unfavorably. 
 In two other cases about half of the disagreement was 
 accounted for by an intelligence quotient just over 
 the dividing line. In the other 4 cases there was 
 nothing in our data which suggested a reason for the 
 inferiority of the school work below apparent intel- 
 lectual ability, though it is possible that a fuller knowl- 
 edge of the facts would have cleared up these cases 
 also. 
 
 An analysis of the one-step disagreements disclosed 
 the same factors, though here there remained a some- 
 what larger number for which the data failed to offer 
 a clear explanation. This amount of disagreement, 
 however, is not particularly significant, since it may 
 come about in a great variety of ways having nothing 
 to do with the validity of the tests. 
 
 In conclusion we may say that even a two-step 
 disagreement between intelligent quotient and the 
 quality of a child's school work does not in itself argue 
 against the validity of the intelligence test. At least 
 90 percent of these disagreements are found to be 
 explainable wholly or partly by other facts. It is 
 especially to be emphasized that rarely, if ever, is a 
 child able to do school work, in the grade where he 
 belongs by age, more than one degree superior to that 
 which the mental age would lead us to expect. On the 
 other hand, it more often occurs that the quality of 
 
RELATION OF INTELLIGENCE TO SCHOOL SUCCESS 109 
 
 TABLE 29 
 Grade Distribution of 676 Children by Mental Age 
 
 Mental 
 
 Grade Attended 
 
 Age 
 
 I 
 
 II 
 
 III 
 
 IV 
 
 V 
 
 VI 
 
 VII 
 
 VIII 
 
 HS 
 I 
 
 HS 
 II 
 
 HS 
 III 
 
 Total 
 
 8 
 
 25 
 25.5% 
 
 4 
 4% 
 
 55 
 56.6% 
 
 18 
 
 18.4% 
 
 19 
 
 19.4% 
 
 1 
 
 1% 
 
 15 
 14.2% 
 
 1 
 
 1% 
 
 6 
 
 5.7% 
 
 17 
 20% 
 
 1 
 
 1% 
 
 1 
 
 ■ 9% 
 
 3 
 
 3.5% 
 
 16 
 
 16.6% 
 
 1 
 
 1.2% 
 
 12 
 
 12.5% 
 
 21 
 
 27% 
 
 
 
 
 98 
 
 9 
 
 24 
 
 24.5% 
 
 4 
 3.8% 
 
 48 
 49% 
 
 98 
 
 10 
 
 30 
 
 28.5% 
 
 6 
 
 7% 
 
 1 
 
 1% 
 
 1.5% 
 
 49 
 
 46.6% 
 
 105 
 
 11 
 
 20 
 
 23% 
 
 8 
 8.3% 
 
 2.6% 
 
 38 
 44.6% 
 
 85 
 
 12 
 
 19 
 
 19.8% 
 
 7 
 9% 
 
 4 
 6% 
 
 40 
 
 41.1% 
 
 96 
 
 13 
 
 29 
 
 37.1% 
 
 21 
 31% 
 
 14% 
 
 16.7% 
 
 19 
 
 24.3% 
 
 78 
 
 14 
 
 16 
 
 23.5% 
 
 10 
 
 28% 
 
 1 
 8.3% 
 
 26 
 
 38.2% 
 
 68 
 
 15 
 16 
 
 21 
 
 58.5% 
 
 9 
 
 75% 
 
 
 36 
 12 
 
 
 
 
 
 
 
 
 
 
 
 676 
 
110 STANFORD REVISION OF BINET-SIMON SCALE 
 
 the school work drops considerably below the level 
 normal to the intelligence quotient in question. The 
 chief causes are ill-health, irregularity of attendance, 
 or the possession of moral or volitional traits unfavor- 
 able to school success. 
 
 Correlation Between Intelligence Quotient and Grade 
 
 Progress 
 
 We have made this comparison for the entire number 
 of subjects, but since there is little opportunity for 
 children below 8 years to become retarded we have 
 included in the following table only those with a mental 
 age of 8 years or more. Grade II is regarded normal 
 for Mental Age 8, Grade III for Mental Age 9, etc. 
 The 8-year mental-age group includes all mental ages 
 from 7 years, 7 months, to 8 years, 6 months, and so 
 on. 
 
 The table of grade distribution by mental age shows 
 that nine-year intelligence is found all the way from 
 Grade I to Grade VII, inclusive; ten-year intelligence 
 from Grade II to Grade VII, etc. Twelve-year intel- 
 ligence, which here ranges from Grade III to Grade 
 VIII, would doubtless have been found in the high 
 school also, if tests had been made there in any con- 
 siderable number. 
 
 Table 30 shows the number and percent who, accord- 
 ing to mental age, are retarded or accelerated 1, 2, 3 
 or 4 years. The table includes only the Mental Ages 
 8 to 16, inclusive. 
 
 Table 30 is given to facilitate comparison with 
 the data of others. It should be emphasized, how- 
 ever, that the method of expressing the degree and 
 amount of retardation and advancement in years 
 for children of all ages taken together is misleading. 
 
RELATION OF INTELLIGENCE TO SCHOOL SUCCESS 111 
 
 TABLE 30 
 
 Amount op Acceleration and Retardation in the Grades When 
 Mental Age is Taken for the Basis 
 
 Grade Below Mental Age 
 
 Normal Grade 
 
 for Mental 
 
 Age 
 
 Grade Above Mental Age 
 
 
 4Yrs. 
 
 or 
 More 
 
 3 
 
 Yrs. 
 
 2 
 Yrs. 
 
 1 
 Yr. 
 
 1 
 Yr. 
 
 2 
 Yrs. 
 
 3 
 Yrs. 
 
 4 
 Yrs. 
 
 Total 
 
 Number 
 
 4 
 
 13 
 
 69 
 
 184 
 
 275 
 
 106 
 
 22 
 
 3 
 
 1 
 
 676 
 
 Percent 
 
 .5 
 
 1.9 
 
 10.2 
 
 27.2 
 
 40.6 
 
 15.6 
 
 3.2 
 
 .4 
 
 .1 
 
 
 It overlooks the fact that a given amount of retarda- 
 tion or acceleration is not equally significant at the 
 different ages. Here, as in the case of mental age, a 
 deviation of one year at the age of 8 is as serious as a 
 deviation of two years at the age of 16. Obviously, 
 when we measure age-grade progress of school chil- 
 dren in terms of years of deviation from normal grade 
 we are using a unit of measure which has no fixed 
 value. Important as this is in the statistical treatment 
 of the retardation problem, it has been consistently 
 ignored in all of the very numerous studies of age- 
 grade progress, from the pioneer work of A3Tes on 
 down. As a result, all of these studies are mislead- 
 ing, particularly in the comparisons made as to the 
 "amount" of retardation or acceleration at the vari- 
 ous ages and in the various grades. 
 
 Reverting to Table 29, it may be pointed out that, 
 after the age of 7 or 8 years, misplacement by one 
 grade is not especially significant, as that could easily 
 happen from any one of a number of causes, such as 
 early or late entrance, illness, a little more or a little 
 less than average industry, etc. But in 112 cases, or 
 nearly 16 percent of all, there is a misplacement of 
 
112 STANFORD REVISION OF BINET-SIMON SCALE 
 
 two grades or more. Eighty-five of these, or 12J^ per- 
 cent of all, are cases of grade retardation below mental 
 age; 26, or nearly 4 percent of all, represent grade 
 acceleration beyond mental age. It is interesting to 
 note that school retardation of 2 years or more (reck- 
 oned on the mental-age basis) is about three times as 
 common as acceleration of 2 years or more. On the 
 basis of chronological age, the proportion of grade ac- 
 celeration to grade retardation is even less than this. 
 Our present task, however, is to find an explanation 
 of the rather surprising disagreement between grade 
 progress and mental age as determined by the scale. 
 Taking up first the 26 children whose grade status is 
 two or more years ahead of their mental age, we find 
 that 19 of these are chronologically over-age for then- 
 grade. Ten of the 19 are from two to four years over- 
 age. In other words, those who are accelerated in 
 school on the basis of mental age are usually retarded 
 on the basis of chronological age, certainly an inter- 
 esting and instructive paradox. The explanation, 
 however, is obvious. The school tends to promote 
 children by age rather than ability, and although the 
 very dull are allowed to become somewhat retarded, 
 this retardation is ordinarily less than would be war- 
 ranted by their actual mental retardation. For ex- 
 ample, there are six children of Mental Age 10 in the 
 sixth grade. Two of these are 14 years of age, two are 
 
 15, and one is 16. Of the two children of Mental Age 
 11 in the eighth grade, one is 17 years old, three are 
 
 16, and five are 15. Only two are normal age for the 
 grade. 
 
 Turning now to the 85 children who are retarded 
 two or more grades below the norm for their mental 
 age, we find that 23 percent are, on the chronological 
 
RELATION OF INTELLIGENCE TO SCHOOL SUCCESS 113 
 
 age basis, actually accelerated, and that over half of 
 the remainder are in the grade where they belong by 
 chronological age. Only 8 percent of those who are 
 retarded two years or more according to mental age 
 are retarded as much as two years by chronological 
 age. This confirms the suspicion that promotion is 
 largely governed by chronological age and helps to 
 explain why children of any given mental age are dis- 
 tributed over such a wide range of grades. There are, 
 of course, other factors which sometimes cause chil- 
 dren to be enrolled in grades too low for their mental 
 age, e. g., irregularity of attendance, illness, and lack 
 of industry. Unfortunately, our blank for supple- 
 mentary data did not call specifically for information 
 on these points. 
 
 Tables 29 and 30 gave the school progress of the 
 children on the basis of mental age. Tables 31 and 32 
 give it on the basis of chronological age. Ages below 
 8 are disregarded, since at this time retardation and 
 acceleration have had little opportunity to occm-. 
 
 Comparison of Tables 29 and 31 reveals the striking 
 fact that, on the whole, the grade location of school 
 children does not fit their mental age much better 
 than it fits their chronological age. Except in the 
 upper years, children of a given mental age are scat- 
 tered over nearly as wide a range of grades as children 
 of the corresponding chronological age. Plainly, the 
 efforts made at school grading fail to give groups of 
 children of homogeneous mental abiUty. 
 
 That this is largely due to the incorrect grading of 
 children of inferior and superior intelligence is easily 
 shown by taking those whose intelligence quotient is 
 practically normal, say between 96 and 105, and find- 
 ing how these distribute themselves in the grades. 
 
114 STANFORD REVISION OF BINET-SIMON SCALE 
 
 TABLE 31 
 
 Age-Grade Distribtttion of Children Above 7 Years op Age 
 (by Chronological Age) 
 
 
 Grade 
 
 Chron. 
 Age 
 
 I 
 
 II 
 
 III 
 
 IV 
 
 V 
 
 VI 
 
 VII 
 
 VIII 
 
 Total 
 
 8 Number 
 Percent 
 
 23 
 24.5 
 
 S 
 4.5 
 
 49 
 52.3 
 
 20 
 21.2 
 
 2 
 1.2 
 
 16 
 14.6 
 
 3 
 
 2.7 
 
 17 
 20 
 
 2 
 2.3 
 
 22 
 28.2 
 
 1 
 1.2 
 
 S 
 6.2 
 
 1 
 1.2 
 
 9 
 
 9.5 
 
 94 
 
 9 Number 
 Percent 
 
 32 
 29.3 
 
 5 
 6 
 
 2 
 2.6 
 
 S3 
 48.4 
 
 109 
 
 10 Number 
 Percent 
 
 20 
 23.5 
 
 7 
 9 
 
 5 
 6.2 
 
 2, 
 2 
 
 41 
 48.2 
 
 85 
 
 11 Number 
 Percent 
 
 18 
 23 
 
 8 
 10 
 
 7 
 7.4 
 
 2 
 2.6 
 
 1 
 
 2.1 
 
 28 
 36 
 
 78 
 
 12 Number 
 Percent 
 
 26 
 32 
 
 11 
 11.6 
 
 1 
 1.3 
 
 36 
 44.4 
 
 81 
 
 13 Number 
 Percent 
 
 35 
 37 
 
 19 
 
 24.3 
 
 2 
 4.2 
 
 1 
 9 
 
 31 
 32.8 
 
 95 
 
 14 Niunber 
 Percent 
 
 19 
 24.3 
 
 9 
 19.1 
 
 1 
 9 
 
 37 
 47.5 
 
 78 
 
 15 Number 
 Percent 
 
 16 Number 
 Percent 
 
 35 
 74.5 
 
 9 
 8.2 
 
 47 
 11 
 
 Total 
 
 
 
 
 
 
 
 
 
 678 
 
 TABLE 32 
 
 Number and Percent op Children Retarded or Accelerated 
 1, 2, 3, or 4 Years for the Ages 8-14 Combined 
 
 
 Eetarded 
 
 In Grade 
 for Age 
 
 Accelerated 
 
 
 
 4 
 
 3 
 
 2 
 
 1 
 
 1 
 
 2 
 
 3 
 
 Total 
 
 Number 
 Percent 
 
 4 
 .6 
 
 15 
 2.4 
 
 55 
 
 173 
 
 275 
 
 89 
 
 9 
 
 1 
 
 620 
 
RELATION OF INTELLIGENCE TO SCHOOL SUCCESS 115 
 
 This method gives the correlation relatively freed 
 from the constant tendency of teachers to over-pro- 
 mote the duU and under-promote the superior chil- 
 dren. Table 33 gives this distribution. 
 
 TABLE 33 
 
 Grade DiSTBiBtrrioN by Chronological Age of Children with 
 Intelligence Quotient between 96 and 105 
 
 Chron. 
 
 Grade 
 
 Age 
 
 I 
 
 II 
 
 III 
 
 IV 
 
 V 
 
 VI 
 
 VII 
 
 VIII 
 
 Total 
 
 8 
 
 9 
 
 25 
 
 4 
 
 3 
 
 3 
 
 2 
 
 
 1 
 
 38 
 
 9 
 
 10 
 
 25 
 
 38 
 
 10 
 
 10 
 
 2 
 
 19 
 
 32 
 
 11 
 
 5 
 
 1 
 
 17 
 
 26 
 
 12 
 
 9 
 
 1 
 1 
 
 10 
 
 ^20 
 
 13 
 
 15 
 6 
 
 14 
 
 31 
 
 14 
 
 8 
 
 4 
 
 15 
 
 30 
 
 IS 
 
 16 
 
 7 
 
 1 
 
 11 
 
 1 
 
 Total 
 
 31 
 
 42 
 
 41 
 
 28 
 
 31 
 
 33 
 
 26 
 
 24 
 
 227 
 
116 STANFORD EEVISION OF BINET-SIMON SCALE 
 
 Of the 227 children appearing in the above table, 
 only 4 who are below the age of 14 are more than one 
 grade removed from the place where they belong by 
 chronological age. AU the two-grade displacements 
 are in the direction of retardation. That is, the child 
 with an intelligence quotient between 96-105 is never 
 found (in our data) two grades advanced in school; 
 and the chances are about 50 to 1 that if he is under 
 14 years of age and tests between 96-105 he will not 
 be as much as two years retarded. (Of 198 children 
 with ages 8-13, 4 are retarded two years.) At ages 14 
 and 15 selection has taken place and the proportion of 
 retardation is naturally much larger. 
 
 Another interesting comparison may be made by 
 taking the extreme intelligence quotients and finding 
 the location in the grades for the exceptionally dull 
 and exceptionally bright children of each chronological 
 age. We have done this for the intelligence quotients 
 above 120 and below 80. The results are shown in 
 Tables 34 and 35. 
 
 Of the 68 children appearing in Table 34, full supple- 
 mentary information is available regarding 34. Of 
 these, not one is doing less than "average" work in 
 the grade attended, while 23 are graded as doing 
 either "superior" or "very superior" school work. Of 
 the 8 who are advanced two grades beyond chrono- 
 logical age, we have supplementary information re- 
 garding 5. Of these 5, every one is graded as doing 
 either "superior" or "very superior" work, and every 
 one is ranked by the teacher as either "superior" or 
 "very superior" in intelligence. 
 
 It will be noted that of the 54 children 7 years old 
 or above, 15 are in the grade where they belong by 
 chronological age, while 3 are even retarded one year 
 
RELATION OF INTELLIGENCE TO SCHOOL SUCCESS 117 
 
 TABLE 34 
 
 Age-Grade Distribution op Children with Intelligence Quotient 120 
 
 OR Above 
 
 Chron. 
 
 Grade 
 
 Age 
 
 Kgn. 
 
 I 
 
 II 
 
 III 
 
 IV 
 
 V 
 
 VI 
 
 VII 
 
 VIII 
 
 Total 
 
 6 
 
 7 
 
 2 
 
 11 
 6 
 
 1 
 3 
 
 2 
 
 7 
 
 2 
 5 
 
 1 
 1 
 
 3 
 
 1 
 
 6 
 
 3 
 
 2 
 
 14 
 11 
 
 8 
 
 
 1 
 
 11 
 
 9 
 
 
 
 6 
 
 10 
 
 1 
 
 3 
 
 8 
 
 11 
 
 1 
 
 1 
 
 8 
 
 12 
 
 
 3 
 
 6 
 
 13 
 
 1 
 
 1 
 
 4 
 
 14 
 
 
 
 
 15 
 16 
 
 
 
 Total 
 
 2 
 
 17 
 
 5 
 
 10 
 
 11 
 
 ' 
 
 11 
 
 4 
 
 2 
 
 68 
 
118 STANFORD REVISION OP BINET-SIMON SCALE 
 
 by chronological age. That is, 18, or one-third of all 
 those 7 years old or older having an intelligence quotient 
 of 120 or above fail to reap any advantage {as far as pro- 
 motion is concerned) from their very superior intelli- 
 gence. They are all doing "very superior" to "aver- 
 age" school work and would doubtless continue the 
 same record if accorded the extra promotions warranted 
 by their intelligence quotient. The reluctance of 
 teachers to give such promotions is probably due both 
 to inertia and to an unwiUingness to part with excep- 
 tionally satisfactory pupils. 
 
 Of the 42 children appearing in the above table, all 
 of whom have between two-thirds and four-fifths in- 
 telligence (intelligence quotient 65 to 80), only two are 
 in the grade where they belong by chronological age. 
 Both of these were doing "very inferior" school work 
 and neither was promoted the following year. Six of 
 the 42 are only one year retarded. Supplementary 
 data are available for only four of the six. Two of 
 these four are doing "very inferior" work, two "in- 
 ferior" work. Of the 18 who are retarded two years, 
 supplementary data are available for 11, four of whom 
 are said to be doing "average" work, four "inferior" 
 work, and three "very inferior" work. Of the 16 re- 
 tarded three years or more, we have supplementary 
 data for 10, three of whom are doing "average" work, 
 four "inferior, "-and three "very inferior." It is inter- 
 esting to note that two of the three who are doing 
 "average" work are four years retarded: one is 13 
 years old and in the third grade, the other is 14 years 
 old and in the fourth grade. This is really what we 
 should expect of high-grade feeble-minded children of 
 13 and 14 years. 
 
RELATION OF INTELLIGENCE TO SCHOOL SUCCESS 119 
 
 TABLE 35 
 
 Age-Grade Distribution of Children with Intelligence Quo- 
 tients Below 80* 
 
 Chron. 
 
 Grade 
 
 Age 
 
 1 
 
 II 
 
 in 
 
 IV 
 
 V 
 
 VI 
 
 VII 
 
 VIII 
 
 Total 
 
 8 
 
 2 
 3 
 
 
 
 
 
 
 
 
 2 
 
 9 
 
 2 
 4 
 
 1 
 
 
 S 
 
 10 
 
 2 
 4 
 
 1 
 
 
 4 
 
 11 
 
 2 
 5 
 1 
 
 
 3 
 
 12 
 
 2 
 
 
 6 
 
 13 
 
 1 
 2 
 1 
 
 2 
 
 11 
 
 14 
 
 1 
 1 
 1 
 
 
 3 
 
 15 
 16 
 17 
 
 1 
 
 2 
 1 
 
 3 
 3 
 2 
 
 Total 
 
 5 
 
 7 
 
 7 
 
 8 
 
 2 
 
 4 
 
 5 
 
 4 
 
 42 
 
 ' (35 of the 42 have intelligence quotients between 70-79.) 
 
120 STANFORD REVISION OF BINET-SIMON SCALE 
 
 The foregoing is suggestive because indicative of 
 what three-quarter intelligence can do. A child of 
 this degree of deficiency is usually two to four years 
 below grade for his age, and his work is usually "infer- 
 ior" or "very inferior." Rarely is he found in the 
 grade where he belongs by chronological age and he 
 never does better than "inferior" work there. 
 
 We learn less from Table 34 of what pupils of intelli- 
 gence quotient 125 can do than we do from Table 35 
 of what pupils of intelligence quotient 75 can do. The 
 reason is that the school does not often give the superior 
 child a chance to work up to his proper level of per- 
 formance. Compared to their possibilities, children of 
 exceptionally superior intelligence are usually retarded, 
 just as we found exceptionally inferior children almost 
 always above the grade where they belong by mental 
 age. Most of the apparently much-retarded children 
 are really accelerates; many of the exceptionally 
 accelerated children are really retardates. 
 
 TABLE 36 
 
 cobrelation between intelligence quotients and intelligence 
 Estimated by the Teachers 
 
 Teachers' 
 
 I Q 
 
 Estimates 
 
 
 
 
 
 
 
 
 Below 80 
 
 80-89 
 
 90-109 
 
 110-119 
 
 120 and up 
 
 Total 
 
 Very Superior 
 Superior 
 Average 
 Inferior 
 Very Inferior 
 
 
 
 2 
 
 10 
 
 11 
 
 8 
 
 2 
 
 3 
 
 37 
 
 22 
 
 4 
 
 7 
 
 60 
 
 184 
 
 34 
 
 6 
 
 4 
 
 29 
 
 39 
 
 
 
 
 
 3 
 17 
 7 
 
 
 
 16 
 
 111 
 
 277 
 
 67 
 
 18 
 
 Total 
 
 31 
 
 68 
 
 291 
 
 72 
 
 27 
 
 389 
 
RELATION OF INTELLIGENCE TO SCHOOL SUCCESS 121 
 
 By the Pearson formula the correlation contained in 
 Table 36 is 0.48. This is about what others have 
 found, and is both large enough and small enough to 
 be significant. That it is moderately high in so far 
 corroborates the tests: that it is not higher means that 
 either the teachers or the tests have made a good many 
 mistakes. 
 
 We note first that 24 children in the above table are 
 placed two steps higher ia the teachers' estimates than 
 the intelligence quotient would suggest, while only 13 
 are displaced two steps downward. This discrepancy 
 would indicate that there is probably some factor caus- 
 ing teachers to overestimate the intelhgence of those 
 whose test performance is low. On looking into the 
 matter we find that of the 24 children misplaced up- 
 ward by the teachers' estimates, 14 are from two to 
 fom- years over-age for their grade. These cases are, 
 therefore, sufficiently explained. It is the teachers 
 who were at fault, not the scale. In judging the intel- 
 ligence of these children they forgot to make allowance 
 for the over-ageness. Finding them about on a par 
 in intellectual matiu-ity with other children of their 
 classes, they judged them equally intelligent. 
 
 Of the remaining 10 children in this group, three 
 were in the kindergarten, where the teacher has little 
 opportunity to form an opinion as to a child's intelli- 
 gence. In another case, that of a boy with an intelli- 
 gence quotient below 80 who was ranked "average," 
 the teacher had contradicted her own estimate by 
 adding an explanatory note which made it clear that 
 the boy was probably a borderline case or even feeble- 
 minded, though possessed of some ability to profit by 
 drill work suited to children a year or two below his 
 age. In four other cases the intelligence quotient was 
 
122 STANFORD EEVISION OF BINET-SIMON SCALE 
 
 just over the dividing line, making the disagreement 
 between it and the teacher's estimate appear ahnost 
 twice as great as it really was. In only two of the 24 
 cases was there no information at hand that would 
 explain all, or nearly all of the disagreement. 
 
 Of the 13 who were displaced two steps downward 
 in the teachers' estimates, we find that five were from 
 one to two years under-age for their grade. Their 
 intelligence had accordingly been judged by a standard 
 which was unfair to them; that is, by a standard based 
 upon the average intelligence of older children. Two 
 were kindergarten children. In another case the 
 teacher, after ranking the child in the "very inferior" 
 group, added a note saying that the child was very 
 deaf and that this might account for the apparent 
 stupidity. The test gave this child an intelligence 
 quotient of 95, which was probably not far from cor- 
 rect. Half the disagreement could be accounted for 
 in two other cases by the presence of the intelUgence 
 quotient near the dividing line. This leaves 3 cases of 
 two-step downward displacement still unexplained, 
 though we are inclined to suspect that if more facts 
 were available, these, too, could have been cleared up. 
 
 Similar reasons appear to account for approximately 
 half of the one-step disagreements. When all the ex- 
 plaiaed disagreements were eliminated from Table 
 9, the correlation rose from .48 to .71. 
 
 Another way to get at the degree of agreement be- 
 tween intelligence quotients and the teachers' esti- 
 mates (as the latter would be if freed from the con- 
 stant error due to neglect of age differences) is to com- 
 pute the correlation separately for those children who 
 are in the grade where they belong by chronological age. 
 When this is done the coefficient of correlation, as may 
 be found from Table 37, rises from .48 to .57. 
 
KELATION OF INTELLIGENCE TO SCHOOL SUCCESS 123 
 TABLE 37 
 
 Teacher's 
 
 
 
 I Q 
 
 
 
 Estimates 
 
 Below SO 
 
 80-89 
 
 90-109 
 
 110-119 
 
 120 or above 
 
 Total 
 
 Very superior 
 Superior 
 Average 
 Inferior 
 Verj- inferior 
 
 
 
 
 
 
 1 
 
 
 
 6 
 
 4 
 3 
 
 1 
 
 27 
 80 
 12 
 
 2 
 
 3 
 
 20 
 
 16 
 
 
 
 
 
 2 
 3 
 1 
 
 
 
 6 
 
 50 
 
 103 
 
 16 
 
 6 
 
 Total 
 
 1 
 
 13 
 
 122 
 
 39 
 
 6 
 
 181 
 
 Still another method of showing how strongly 
 teachers tend to base their estimate of a child's intel- 
 ligence upon the quality of his school work, to the 
 neglect of age differences, is to take their classification 
 of a group of children according to iatelUgence, and 
 their classification of the same children according to 
 school work, and ascertain the degree of correlation 
 between the two groupings. We have done this, with 
 the result shown in Table 38. 
 
 TABLE 38 
 
 Correlation Between the Teachers' Groupings Accordinq to 
 Intelligence and According to Qualitt op School Work 
 
 Teachers' 
 Classlflcation 
 
 Teachers' Classiflcatioii According to Intelligence 
 
 according to 
 School Work 
 
 Very 
 Inferior 
 
 Inferior 
 
 Average 
 
 Superior 
 
 Very 
 Superior 
 
 Total 
 
 Very Superior 
 Superior 
 Average 
 Inferior 
 Very Inferior 
 
 
 
 
 
 4 
 13 
 
 
 
 
 
 12 
 
 45 
 
 11 
 
 
 
 16 
 
 212 
 
 35 
 
 2 
 
 3 
 
 83 
 
 22 
 
 1 
 
 . 
 
 12 
 6 
 
 
 
 
 15 
 
 105 
 
 246 
 
 85 
 
 26 
 
 Total 
 
 17 
 
 68 
 
 265 
 
 109 
 
 18 
 
 477 
 
124 STANFORD REVISION OF BINET-SIMON SCALE 
 
 The correlation is .82 and would probably have been 
 still higher if the supplementary form filled out by the 
 teachers had not contained the specific instruction to 
 estimate the intelligence of a child "in comparison 
 with other children of the same age." In spite of this 
 injunction, they have obviously ignored age differences 
 and estimated intelUgence chiefly on the quality of 
 the child's school work in the grade where he happened 
 to be. They have failed to realize that quality of 
 school work is no index of intelligence unless age is 
 taken into account. The question should be, of course, 
 not: "is this child doing his school work well?" but 
 rather: "in what school grade should a child of this 
 age be doing satisfactory work?" A high-grade im- 
 becile may do average work in the first grade and a 
 high-grade moron average work in the third or fourth 
 grade, provided only they are sufficiently over-age for 
 the grade in question. 
 
 Our experience in testing children for segregation in 
 special classes has time and again brought this pecuUar 
 fallacy of teachers to our attention. We have often 
 found one or more feeble-minded children in a class 
 after the teacher had confidently asserted that there 
 was not a single exceptionally dull child present. In 
 every case where there has been opportunity to follow 
 the later school progress of such a child the substan- 
 tial accuracy of the mental test has been confirmed. 
 
 The following are typical examples of the neglect of teachers to take 
 the age factor into account when estimating the intelligence of the 
 child over-age for his grade: 
 
 A. R. Boy, age 17, mental age 11, sixth grade, school work "nearly 
 average," teacher's estimate of inteUigence "average." Test plainly 
 shows this child to be a high-grade moron, or borderliner at best. Had 
 attended school regularly 11 years and had made 6 grades. Teacher 
 had compared child with his 12-year-old classmates. 
 
 H. A. Boy, age 13, mental age 9-6, low fourth grade, school work 
 "inferior," teacher's estimate of intelligence "average." The teacher 
 
EELATION OF INTELLIGENCE TO SCHOOL SUCCESS 125 
 
 blamed the inferior quality of school work to "bad home environ- 
 ment." As a matter of fact, the boy's father is feeble-minded and the 
 normaUty of the mother is questionable. An older brother is in a 
 reform school. We are perfectly safe in predicting that this boy will 
 not complete the eighth grade, even if he attends school till he is 21 
 years of age. 
 
 F. I. Boy, age 12-11, mental age 9-4, third grade, school work 
 "average," teacher's estimate of inteUigence "average," social environ- 
 ment "average," health good and attendance regular. IntelUgence 
 and school success are what we should expect of an average 9-year old. 
 
 D. A. Boy, age 12, mental age 9-2, third grade, school work "in- 
 ferior," teacher's estimate of inteUigence "average." Teacher im- 
 putes inferior school work to "absence from school and lack of inter- 
 est in books"! We have yet to find a child of 75 inteUigence quotient 
 who was particularly interested in books or enthusiastic about school. 
 
 C. U. Girl, age 10, mental age 7-8, second grade, school work 
 "average," teacher's estimate of inteUigence "average." Teacher 
 blames adenoids and bad teeth for retardation. No doubt of child's 
 mental deficiency. 
 
 P. I. Girl, age 8-10, mental age 6-7, has been in first grade two 
 years and a half, school work "average," teacher's estimate of intelli- 
 gence "average." The mother and one brother of this girl are feeble- 
 minded. 
 
 H. O. Girl, age 7-10, mental age 5-2, first grade for 2 years, school 
 work "inferior," teacher's estimate of inteUigence "average." The 
 teacher, nevertheless, adds: "This chdd is not normal, but her abiUty 
 to respond to drUl shows that she has inteUigence." It is true that 
 even feeble-minded chUdren of 5-year inteUigence are able to profit a 
 Uttle from driU. Their weakness comes to Ught in their inabihty to 
 perform higher types of mental activity. 
 
 The following are examples of the under-estimation 
 of intelligence and school ability of children who are 
 under-age for their grade: 
 
 M. L. Girl, age 11-2, mental age "average adult" (16), sixth 
 grade, school work "superior," teacher's estimate of intelligence 
 "average." Teacher credits superior school work to "unusual home 
 advantages." Father is a coUege professor. The teacher considers 
 the child accelerated in school. In reaUty, she ought to be in the 
 second year of the high school, instead of in the sixth grade. 
 
 H. A. Boy, age 11, mental age 14, sixth grade, school work "aver- 
 age," teacher's estimate of inteUigence "average." According to the 
 supplementary information the boy is "wonderfuUy attentive," 
 "studious," and possessed of "aU-round ability." The estimate of 
 "average inteUigence" is probably due to the fact that he was com- 
 pared with classmates who averaged about a year older. 
 
 K. R. Girl, age 6-1, mental age 8-5, second grade, school work 
 "average," teacher's estimate of inteUigence "superior," social environ- 
 ment "average." Is it not evident that a chUd from ordinary social 
 
126 STANFORD REVISION OF BINET-SIMON SCALE 
 
 environment who does work of average quality in the second grade 
 when barely 6 years of age, and who has an intelligence quotient of 
 about 140, should be judged "very superior" rather than merely 
 "superior" in inteUigence? 
 
 S. A. Boy, age 8-10, mental age 10-9, fourth grade, school work 
 "average," teacher's estimate of intelligence "average." Teacher 
 attributed school acceleration to "studiousness" and "deUght in 
 school work." Our own guess would be that these traits are, rather, 
 indications of unusually superior intelligence. 
 
 In a special study of a group of superior children, 
 tested separately from the present investigation, we 
 have found even more striking examples of the difficulty 
 teachers have in recognizing superior ability. One 
 case was that of a boy aged 10-6 with an intelligence 
 quotient of 148. He was in the sixth grade, doing 
 "superior" work there, and yet was judged by the 
 teacher to have "no unusual ability." It was learned 
 from the parents that the boy is distantly related to 
 Meyerbeer, the composer, and that at an age when 
 most children are reading fairy stories, he has a passion 
 for difficult medical literature and text books in phys- 
 ical science. 
 
 The question has suggested itself, whether teachers' 
 estimates of intelligence vary in reliability with chil- 
 dren of different ages. We have divided our children 
 into three groups, according. to age, and have com- 
 puted for these groups separately the correlation 
 between the intelligence quotient and the teachers' 
 estimates. Ages 5, 6, 7 and 8 were placed in one 
 group; Ages 9, 10 and 11 in another; and Ages 12, 13, 
 14, and 15 in a third. The coefficients were, in order, 
 .48, .60 and .46. It appears, therefore, that teachers 
 probably make fewer errors with pupils of the middle 
 group, though the difference is not great. 
 
 Such facts as we have set forth in this chapter sug- 
 gest that, while the judgment of a teacher regarding a 
 
EELATION OF INTELLIGENCE TO SCHOOL SUCCESS 
 
 child's school success and intelligence may, if properly 
 safeguarded, afford valuable data to supplement the 
 results of the intelligence test, the assistance is more 
 likely to be in the other direction; more often it is the 
 test which can keep us from being misled by the 
 erroneous judgment of the teacher. 
 
 '" ' '^^-rp SUMMARY 
 
 1. The coirelation between intelligence quotient and 
 the quaUty of the school work as judged by the teachers 
 is .45. An examination of the marked cases of dis- 
 agreement between intelligence quotient and school 
 work shows that these are due largely to the teachers' 
 neglect of age differences in estimating quality of 
 school work. 
 
 2. The correlation between intelligence quotient and 
 the teachers' rankings according to intelligence is .48. 
 Detailed study of the cases of disagreement justifies 
 the conclusion that they are due mainly to certain 
 constant errors to which teachers are subject in esti- 
 mating a child's intelligence. Here, as in judging 
 quality of school work, the most common error is that 
 of overlooking age differences. Teachers judge in- 
 teUigence mostly by thF'quahty of school work in the 
 grade where the child happens to be located. This 
 results in over-estimating the intelligence of older, 
 retarded children, and under-estimating the intelligence 
 of the younger, advanced children. 
 
 3. The wider disagreements between intelUgence 
 quotient and grade status are confined chiefly to those 
 children who are superior to, or below the average in 
 ability. The explanation for this has been found in 
 the fact that the tendency of the school is to promote 
 children by age rather than by abiUty. Those who 
 
128 STANFORD REVISION OF BINET-SIMON SCALE 
 
 have an intelligence quotient between 96 and 105 are 
 hardly ever more than one grade removed from the 
 location which is normal to their mental age. 
 
 4. The child with an intelligence quotient of 120 or 
 above is rarely found below the grade for his chrono- 
 logical age, and occasionally he is one or two grades 
 above. Wherever located, his work is nearly always 
 superior, and the evidence suggests strongly that this 
 superiority of school work would continue even if 
 extra promotions were granted. Superior children are 
 seldom allowed to reap the advantage, in school prog- 
 ress, to which their superiority fairly entitles them. 
 
 5. The child of 70-79 intelligence quotient never 
 does satisfactory work in the grade where he belongs 
 by chronological age. After the age of 8 or 9 years 
 such a child is usually found doing "very inferior" to 
 "average" work in a grade two to four years below his 
 
 , 6. Although the disagreements between intelligence 
 I quotient on the one hand and grade progress, quality 
 j of school work, and teachers' estimates of intelligence 
 / on the other hand would at first seem to justify serious 
 I misgivings as to the value of the intelligence scale, 
 / these same disagreements, on closer examination, are 
 
 f*^ \ found to offer the strongest evidence in support of the 
 
 //\ test method. 
 
CHAPTER VII 
 
 THE VALIDITY OF THE INDIVIDUAL TESTS 
 Criteria of a Test's Validity 
 
 The first task in the construction of an intelligence 
 scale is to select tests which are really tests of iatelli- 
 gence, tests which are not too much influenced by age, 
 home environment or school instruction apart from 
 native endowment. There are three criteria which a 
 test must satisfy before it can be accepted as a valid 
 measure of intelligence. In the first place, since we 
 know that intelligence is^tq a certain extent a functioSiT 
 of age,raT;esTj o^e vaUd must^ show an iacrease from 
 year to year inTHepercentage of unselected children. 
 that pass it . This is the criterion on which Binet 
 chiefly reUed. Nearly all the tests which he finally 
 included in his scale satisfy this criterion fairly well, 
 though some show a more rapid increase than others. 
 
 This, however, is not sufficient. Many other traits 
 besides intelligence are also functions of age. Height, 
 weight, chest girth, length of forearm, in fact, any 
 physical trait influenced by growth would show a, 
 steady increase from age to age in the percentage 
 that pass a given standard. Yet it is easy to show that 
 tests of this kind have no place in an intelligence scale. 
 If 100 unselected 10-year-olds were measured for 
 length of forear m it would of coiu-se be found that the 
 ave rage for all considerably -excee3s~tfiatTor'"9^yeSr' 
 olds; but it would also doubtless be found that this 
 is little if any more true of 10-year-olds who have 
 superior intelligence than of lO-year-olds who have 
 inferior inteligence. That is, although intelligence and 
 
 129 
 
130 STANFORD BEVISION OF BINET-SIMON SCALE 
 
 length of forearm are both functions of age, they have 
 no direct relationship to each other. Such a test 
 would not be found coherent with any already existent 
 intelligence scale. Similarly, if a given test in the 
 Binet series does not agree with the scale as a whole, 
 if 10-year children who by the scale have 11-year intel- 
 ligence do not pass it any more frequently than those 
 10-year children who have 9-year intelligence, then 
 either this test is worthless or the scale as a whole 
 lacks validity. The entire scale must be coherent. 
 
 But coherency and age-increase in the percentage 
 that pass do not themselves guarantee the validity of 
 a series of tests for the measurement of intelUgence. 
 A set of tests made up of a great variety of physical 
 measurements might very well satisfy both of these 
 criteria. If we have no already existing intelligence 
 scale with which to compare an individual test, then 
 we must compare the test with intelligence as other- 
 wise estimated, for example, with teachers' rankings. 
 If children who are ranked as intelUgent succeed with 
 it no better than those who are ranked as dull, then 
 the test is of doubtful vaUdity. 
 
 For our present purposes the third criterion may be 
 left out of account in judging the validity of individual 
 tests of the Binet scale. It has been amply demon- 
 strated that the scale as a whole gives a fairly reUable 
 index of intelligence. Its results always show a 
 reasonably high correlation with intelligence as judged 
 by teachers or other observers. We have already 
 shown that its correlation with school success is fairly 
 high, particularly when allowance is made for certain 
 tendencies to error in the estimation of school success. 
 Its use with feeble-minded children in institutions has 
 been especially convincing. Long-continued observa- 
 
VALIDITY OF THE INDIVIDUAL TESTS 131 
 
 tion of such children rarely necessitates any serious 
 correction of its verdict. 
 
 As for the first essential — the requirement of an 
 increase in the percentage of passes from year to year 
 — ^it is evident from all the available statistics that all 
 the tests which we have included in the revision meet 
 this criterion in a fairly satisfactory way. Some tests 
 show more rapid increases than others, but not one is 
 passed by equal percentages in three successive years. 
 
 Accordingly, the criterion of most importance for 
 our purpose is the second one — that of coherency. 
 Since we know that the scale as a whole is fairly reli- 
 able, we can measure each individual test against the 
 entire scale. A test which gives results out of harmony 
 with the results of the scale as a whole can not be con- 
 sidered a satisfactory test of intelligence, whatever 
 increase it may show in the percentage that pass it 
 from year to year. This increase might be due to 
 other factors than intelligence, such as school instruc- 
 tion or the incidental experiences which come with 
 increasing age. \^ 
 
 One way of applying this criterion would be to classify ^s:^ 
 all our subjects by mental age as determined by the 
 scale and then note the number that pass a given test 
 at successive mental ages. This method gives valu- 
 able information, and we have had to rely on it to a 
 large extent in evaluating and placing the tests of the 
 upper-year groups. It has, however, one objectionable 
 feature; the results are more or less influenced by age, 
 apart from intelligence. Children of 8-year mental 
 age, for example, range in chronological age all the way 
 from 53^ or 6 years to 11 or 12 years, and it is conceiv- 
 able that these large age differences might have a 
 considerable influence on the number that pass a given 
 
^/' 
 
 132 STANFORD REVISION OF BINET-SIMON SCALE 
 
 test. The only way to separate the influence of intelli- 
 gence from that of age is to take a large number of 
 unselected children of one chronological age and find 
 the percentage of passes separately for the bright and 
 dull children of that group. 
 
 Correlation of the Individual Tests with Intelligence 
 
 Quotient 
 
 Following the foregoing plan, we have divided the 
 children of each chronological age into three groups 
 according to magnitude of intelligence quotient. We 
 have placed in the middle or normal group those chil- 
 dren of a given age having an intelligence quotient 
 between 96 and 105, in the inferior group those with 
 an intelligence quotient below 96, and in the superior 
 group those with an intelligence quotient of 106 or 
 above. At most of the ages this gives three groups of 
 about the same size. Had we tested a larger number 
 of children of each age, it would probably have been 
 better to place more children in the middle group, say 
 all between 91 and 110 intelligence quotient. This 
 would have heightened the contrast between the inferior 
 and superior groups. However, such a plan would 
 have placed about 60 percent of our cases of a given 
 age in the middle group and left only about 20 percent, 
 only 12 to 20 children, for each of the other groups. 
 Accordingly, in order to obtain three groups of nearly 
 equal size we have included in the middle group those 
 with an intelligence quotient between 96 and 105. 
 
 Table 39 shows the results of this comparison. The 
 figures are in all cases the percentages of passes for 
 children of the chronological age in which the test is 
 located. The three columns give these percentages 
 for children with inteUigence quotient 95 or below, 
 96-105, and 106 or above, respectively. 
 
VALIDITY OF THE INDIVIDUAL TESTS 
 
 133 
 
 TABLE 39 
 
 a m 
 ■ffi 0! 
 
 a" 
 
 P4 S 
 
 V 
 
 1. Weights 
 
 2. Colore 
 
 3. Aesth. Comp 
 
 4. Def. by use. . 
 
 5. Patience. . . . 
 
 6. Commissions 
 Al. Age 
 
 I 
 
 VI 
 
 1. Right and left 
 
 2. Mutilated pict 
 
 3. Thirteen pennies. . . . 
 
 4. Comprehension (2) . . 
 
 5. Four coins 
 
 6. 16-18 syllables 
 
 lAI. A.M. and P.M 
 
 VII 
 
 1. Fingers 
 
 2. Descript. of picture . 
 
 3. Five Digits 
 
 4. Bow knot 
 
 ,5. Differences 
 
 '6. Diamond 
 
 Al. Days of week 
 
 Al. Three Digits Reversed 
 
 VIII 
 
 1. BaU and field 
 
 2. 20-1 
 
 3. Comprehension (3) . . . 
 ;4. Similarities 
 
 5. Superior def 
 
 6. Vocabulary (20) 
 
 'Al. Six Coins 
 
 Al. Dictation 
 
 
 If 
 
 75 
 
 84 
 
 75 
 
 89 
 
 69 
 
 84 
 
 69 
 
 79 
 
 75 
 
 95 
 
 75 
 
 90 
 
 69 
 
 95 
 
 70 
 
 89 
 
 66 
 
 86 
 
 77 
 
 96 
 
 68 
 
 85 
 
 79 
 
 83 
 
 65 
 
 78 
 
 82 
 
 86 
 
 68 
 
 85 
 
 52 
 
 80 
 
 74 
 
 80 
 
 71 
 
 78 
 
 74 
 
 95 
 
 58 
 
 82 
 
 62 
 
 85 
 
 55 
 
 75 
 
 60 
 
 69 
 
 55 
 
 83 
 
 80 
 
 80 
 
 57 
 
 83 
 
 60 
 
 80 
 
 57 
 
 74 
 
 64 
 
 71 
 
 90 
 
 100 
 
 IX 
 
 1. Date 
 
 2. Weights 
 
 3. Change 
 
 4. Four Digits Reversed 
 
 5. Three words 
 
 6. Rhymes 
 
 Al. Months 
 
 Al. Stamps 
 
 X 
 
 1. Vocabulary (30) 
 
 2. Absurdities 
 
 3. Desi^ 
 
 4. Reading and rept. . . . 
 
 5. Comprehension (4) . . . 
 
 6. Sixty Words 
 
 Al. Six Digits 
 
 Al. 20-22 SyUables 
 
 Al. Healy's form board. . . 
 
 XII 
 
 1. Vocabulary (40) 
 
 2. Abstract words 
 
 3. Ball and field 
 
 4. Disarranged sentence 
 
 5. Fables (score 4) 
 
 6. Five Digits Reversed . 
 
 7. Picture interpreted. . . 
 
 8. Similarities 
 
 XIV 
 
 1. Vocabulary (50) 
 
 2. Induction 
 
 3. President and K 
 
 4. Prob. of fact 
 
 5. Arith. reas 
 
 6. Clock* 
 
 Al. Seven Digits 
 
 LO- 
 
 fri XI 
 
 48 
 37 
 39 
 45 
 49 
 39 
 39 
 40 
 
 20 
 35 
 45 
 45 
 25 
 30 
 55 
 45 
 55 
 
 36 
 40 
 36 
 45 
 39 
 48 
 21 
 47 
 
 42 
 41 
 22 
 44 
 25 
 59 
 50 
 
 * Figures for clock problem are on basis of 1 success out of 2 trials. 
 
134 STANFOKD REVISION OF BINET-SIMON SCALE 
 
 Table 39 contains not a few surprises. Some of the 
 tests which have been most criticized for their sup- 
 posed dependence on extraneous factors here show a 
 high correlation with intelligence. Among these are 
 "days of week," "stamps," "13 pennies," "president 
 and king," "rhymes," "age," "right and left" and 
 "picture interpretation." Others having a high reli- 
 ability are "vocabulary," "arithmetical reasoning," 
 "giving differences," "diamond," "date," "reversed 
 digits," "fables," "disarranged sentences," "60 words," 
 "mutilated pictures" and "absurdities." 
 Among the poorest are "repeating digits" (direct 
 / order), "naming coins," "morning and afternoon," 
 / "definition by use,"' "designs" and "aesthetic com- 
 ,' parison." Three of the tests which had been included 
 in our original trial series correlated so little with in- 
 telligence that we have thrown them out. They are 
 Binet's suggestion test (in his 1911 revision), Healy 
 and Femald's Construction Puzzle B, and our test of 
 drawing an apple with a pencil through it. The 
 figures for these tests are as follows: 
 
 TABLE 40 
 
 
 Percent 
 
 passing 
 
 below I Q 
 
 96 
 
 Percent 
 passing 
 
 IQ 
 96-105 
 
 Percent 
 
 passing 
 
 above I Q 
 
 105 
 
 Binet's suggestion test (Yr. X) 
 Healy and Fernald Construction 
 
 Puzzle B (Yr. XII) 
 Drawing apple and pencil (Yr. VIII) 
 
 80 
 
 75 
 62 
 
 62 
 
 75 
 63 
 
 89 
 
 65 
 
 51 
 
 Tests that correlate moderately with intelligence 
 include "arranging weights," "three commissions," 
 "colors," "fingers," "picture description," "months," 
 "change," "similarities," "superior definitions," "read- 
 
VALIDITY OF THE INDIVIDUAL TESTS 135 
 
 ing for memories," "abstract words," "induction 
 test," "problems of fact," "clock" and "bow-knot." 
 A test that makes a good showing by this method 
 of comparison, whatever it appears to be from mere 
 inspection, is a real measure of inteUigence. Hence- 
 forth, it stands or falls with the scale as a whole. ..That 
 
 , so few o f the tests shouM„i&il Jo.jhos 3 re^.Qnably 
 
 Jbigh co rrelati on with intelUgence is_st.riking-ey,idfiBge. 
 
 "of the_mgmj^t^;_j;ndjgYchaiagka^ 
 
 ■" It Is especially interesting to compare the facts set 
 forth in Table 39 with Meumann's classification of the 
 tests as "tests of maturity," "tests of milieu," and 
 "tests of endowment." Of the good or superior tests, 
 Meumann has classified the foUowing as tests of 
 milieu: "counting pennies," "colors," "vocabulary," 
 "days of week," "months," "date," "right and left," 
 "20-0," "ball and field," and "60 words." Other 
 excellent tests of intelHgence he classifies as tests of 
 maturity. In the light of our results it is hardly neces- 
 sary to enter into the a priori criticisms which Decroly 
 and Degand, Ayres, and others have made of certain 
 of the tests. The classification and criticism of tests by 
 mere inspection may form an interesting pastime, 
 but it can hardly be taken seriously as a contribution 
 to science. 
 
 It is not impUed that a test which makes a good 
 showing in Table 39 is entirely free from other influ- 
 ences than intelligence. On the contrary, age and 
 environment may affect almost every test to a greater 
 or lesser degree. To determine the exact extent to 
 which this may be true for even a single test, would 
 require an extensive investigation. 
 
136 STANFOED KEVISION OF BINET-SIMON SCALE 
 
 The Influence of School Instruction 
 
 We have the following data to offer regarding the 
 influence of school instruction upon certain of the 
 tests in the highest groups. A comparison was made 
 of the percentages of passes made on individual tests 
 by "educated" and by "little-educated" adults who 
 tested at the "average adult" level, that is, between 
 15 and 17 mental age. Of the adults tested by Knol- 
 lin, Johnson, Zeidler and Terman there were 28 of the 
 "average adult" level who had progressed through 
 the high school or beyond and 33 who had not gone 
 beyond the eighth grade. Of those who reached the 
 "superior adult" level (17-19 mental age) there were 
 17 of high-school education and 15 of common-school 
 education or less. Table 41 shows the percentages of 
 passes of these two groups on each test in the four 
 highest groups of tests. 
 
 The striking thing in this table is the evident lack of 
 any significant influence of school training on the 
 ability to pass most of the tests. The only ones in 
 which the high-school group shows a marked super- 
 iority are "sense of selection," "ingenuity," "abstract 
 pairs" (XVI) and "problems of fact." The common- 
 school group has the advantage in "ball and field," 
 "5 digits reversed," "6 digits reversed," "7 digits" 
 (direct order) and "26-28 syllables." "Vocabulary," 
 "fables," "paper cutting" Binet, "clock," "arith- 
 metical reasoning," and "disarranged sentences" show 
 no significant difference between the two groups. 
 
 We have often been warned by skeptical friends 
 that size of vocabulary is determined by schooling and 
 not by intelligence, that success with the fables de- 
 pends wholly upon moral instruction, that "arith- 
 
VALIDITY OF THE INDIVIDUAL TESTS 
 
 137 
 
 TABLE 41 
 
 Pebcentages op Average and op Superior Adults Who Pass the 
 Several Tests op Age XII and Above 
 
 Test 
 
 "Average Adults " 
 (15-17 mental age) 
 
 H. S. 
 Group 
 
 Com. Sch. 
 Group 
 
 "Superior Adults" 
 (17-19 mental age) 
 
 H. S. 
 Group 
 
 Com. Sch. 
 Group 
 
 XII 
 
 1. Vocabulary (40) 
 
 2. Abstract words 
 
 3. Ball and Field 
 
 4. Disar. Sentences 
 
 5. Fables (score 4) 
 
 6. Five digits reversed. . 
 
 7. Pict. interpret 
 
 8. Similarities 
 
 XIV 
 
 1. Vocabulary (50) 
 
 2. Induction 
 
 3. Pres. and king 
 
 4. Prob. of fact 
 
 6. Arith. reas 
 
 6. Clock* 
 
 Al. Seven digits 
 
 XVI 
 
 1. Vocabulary (65) 
 
 2. Fables (8) 
 
 3. Abstract pairs 
 
 4. Box problem 
 
 5. Six digits reversed . . . 
 
 6. Code 
 
 XVIII 
 
 1. Vocabulary (75) 
 
 2. Paper cutting 
 
 3. Eight digits 
 
 4. Sense of selection. . . . 
 
 5. Seven digits reversed 
 
 6. Ingenuity 
 
 100 
 
 100 
 
 100 
 
 94 
 
 97 
 
 100 
 
 70 
 
 85 
 
 84 
 
 94 
 
 91 
 
 100 
 
 90 
 
 94 
 
 100 
 
 74 
 
 92 
 
 93 
 
 97 
 
 84 
 
 100 
 
 97 
 
 85 
 
 100 
 
 100 
 
 97 
 
 100 
 
 97 
 
 85 
 
 100 
 
 89 
 
 83 
 
 100 
 
 97 
 
 85 
 
 100 
 
 89 
 
 79 
 
 94 
 
 91 
 
 85 
 
 100 
 
 60 
 
 90 
 
 93 
 
 90 
 
 85 
 
 100 
 
 79 
 
 74 
 
 86 
 
 91 
 
 73 
 
 100 
 
 51 
 
 76 
 
 86 
 
 34 
 
 61 
 
 73 
 
 38 
 
 26 
 
 75 
 
 35 
 
 30 
 
 100 
 
 30 
 
 28 
 
 77 
 
 30 
 
 34 
 
 73 
 
 63 
 
 28 
 
 81 
 
 no data 
 
 no data 
 
 no data 
 
 42 
 
 20 
 
 85 
 
 100 
 100 
 
 90 
 100 
 
 95 
 
 95 
 100 
 
 90 
 
 100 
 95 
 87 
 
 100 
 96 
 95 
 87 
 
 100 
 
 82 
 100 
 95 
 77 
 67 
 
 83 
 89 
 67 
 57 
 no data 
 70 
 
 * Figures for clock test are on the basis of 1 success in 2 trials. 
 
138 STANFORD EEVISION OF BINET-SIMON SCALE 
 
 metical reasoning" and the "paper-cutting" test will 
 be greatly influenced by recency of instruction in 
 arithmetic and geometry, respectively, and that the 
 ability to repeat sentences and digits depends almost 
 purely upon that rote memory which is so diligently 
 cultivated in the schools. From the data presented 
 above, however, it is evident that criticisms based on 
 off-hand opinion have little value. 
 
 The Influence of Age and Experience 
 
 The influence of maturity, apart from native endow- 
 ment, is difiicult to isolate. We can, of course, compare 
 older and younger individuals of the same mental age 
 with respect to the percentages that pass individual 
 tests, but this gives us the combined influence of ma- 
 turity and experience. The 16-year-old of 10-year 
 intelligence is not only more mature than the 10-year- 
 old of 10-year intelligence; he has had also the advan- 
 tage of 6 years additional experience and opportunity 
 to learn. The best we can do, however, is to treat 
 these two influences as one, which we may call the 
 "age factor," meaning thereby the combined influence 
 of age, as such, and of the experience which goes with 
 age. 
 
 The influence of the "age factor" may be seen by 
 comparing Williams' delinquents and Knollin's un- 
 employed of a given mental age with unselected school 
 children of that chronological age. Such comparisons 
 were made for the Mental Ages 9 to "average adult." 
 It will be remembered that most of the deUnquents 
 were between 12 and 21 years of age and that most of 
 them were mentally retarded (nearly a third were 
 classed as feeble-minded). The unemployed were 
 somewhat less inferior and ranged from 20 to 65 years 
 
VALIDITY OF THE INDIVmUAL TESTS 139 
 
 of age, with a median of 34 years. Accordingly, if the 
 delinquents and unemployed of the mental age 10 
 years differ greatly from unselected 10-year children, 
 the difference may be attributed to the superior 
 chronological age of the former. 
 
 A good deal of such influence was foimd in certain 
 of the tests. The influence, however, is not always in 
 the same direction. With some tests, age tends to 
 increase, with others to decrease, the percentage of 
 successes. Indeed, there are more marked cases of 
 negative influence than of positive. Among those 
 negatively influenced are: "rhymes," "six digits," 
 "60 words," "20-22 syllables," "disarranged sen- 
 tences," "sense of selection" and "fables"; also, 
 though to a less extent, "date," "three words," "de- 
 signs," "reading for memories," "26-28 syllables," 
 "five digits reversed" and "similarities" (three 
 things). In finding rhymes, for example, Wilhams' 
 older delinquents and KnoUin's unemployed adults do 
 no better' at Mental Age 13-14 than unselected chil- 
 dren of 10 years. Almost as great a difference in the 
 same direction is found in the test of repeating six and 
 seven digits, naming 60 words, repeating five digits 
 backwards, and giving sense of selection. 
 
 The positive influence of age, i. e., that which causes 
 increase in the percentage of passes, is in evidence with 
 the following tests: "induction," "physical relations," 
 "months," "vocabulary," "comprehension" (Age X), 
 "making change," "problems of fact" and "enclosed 
 boxes." In "comprehension" (Age X), for example, 
 KnoUin's adults of 10-year mental level do about as 
 well as unselected children of 11 years. In the induc- 
 tion test the adults of 13-year mental level are far 
 superior to unselected children of 14 years, and the 
 
140 STANFOKD REVISION OF BINET-SIMON SCALE 
 
 difference is almost as marked for most of the other 
 tests listed above. 
 
 Kuhlmannls data on the influence of age are in 
 some respects the most valuable yet offered on this 
 subject. 1 His method was to compare older and younger 
 feeble-minded children with reference to the percent- 
 age that passed each individual test in the Binet 1908 
 scale from Year III to Year X. Evidence of more or 
 less influence of age was found with the following tests : 
 "pointing to eyes, nose and mouth," "giving last 
 name," "repeating three digits," "copying a square," 
 "counting four pennies," "definitions by use"; "re- 
 peating five digits," "naming four coins," "reading 
 for two memories," "naming days of the week" and 
 "naming the months." In only three of the tests, 
 however, was the influence great enough to amount to 
 a displacement of the test by as much as one year. 
 These were "repeating 3 digits," "definitions by use" 
 and "naming four coins." 
 
 i'i ntner a^ Paterson made a similar comparison of 
 feeble-minde3~cHildren above and below the chrono- 
 logical age of 15 years with respect to the percentage 
 at each mental age that passed two tests — "days of 
 the week" and "months of the year." Their results, 
 which are given in Table 42, show a fairly large influence 
 of age. The mental ages were determined by the 
 Goddard revision.^ 
 
 / iKuhlmann: The Binet-Simon tests of intelligence in grading 
 feeble-minded children. J. of Psycho. Asthenics, 16: June, 1912, pp. 
 173-193. See especially pp. 182-185. 
 2R. Pintner and D. G. Paterson: Experience and the Binet-Simo n 
 
 , tests, The Psychological Clinic, 8: Dec, 1914, pp. 197-200. 
 
VALIDITY OF THE INDIVIDUAL TESTS 
 
 141 
 
 TABLE 42 
 
 NtTMBEE OF FbBBLE-MiNDBD AbOVE AND BbLOW 15 YeAES OF AoE THAT PASSED 
 
 Certain Tests. (From Pesttneb and Patbeson) 
 
 
 Chron. 
 Age 
 
 Mental Age 
 
 Tests 
 
 4 
 
 5 
 
 6 
 
 7 
 
 8 
 
 9 
 
 \^ 
 
 No. 
 
 Per- 
 cent 
 
 No. 
 
 Per- 
 cent 
 
 No. 
 
 Per- 
 cent 
 
 No. 
 
 Per- 
 cent 
 
 No. 
 
 Per- 
 cent 
 
 No. 
 
 Per- 
 cent 
 
 Days 
 )f Week 
 
 Vlonth 
 )f Year 
 
 Below 15 
 Above 15 
 
 Below 15 
 Above 15 
 
 21 
 28 
 
 4.8 
 14.3 
 
 52 
 50 
 
 19 
 36 
 
 27 
 54 
 
 5.3 
 13.9 
 
 95 
 
 77 
 
 66 
 70 
 
 59 
 80.5 
 
 10.6 
 28.6 
 
 100 
 
 127 
 
 100 
 112 
 
 87 
 98.5 
 
 35 
 68 
 
 72 
 128 
 
 71 
 128 
 
 98.6 
 100 
 
 77.5 
 92.3 
 
 31 
 101 
 
 31 
 101 
 
 100 
 100 
 
 87 
 93 
 
 The following tests are also thought by Pmtner and 
 Paterson to be subject to age influence, although no 
 data are offered in support of their belief: "counting 
 13 pennies," "copying a square," "diamond," "nam- 
 ing colors," "telling forenoon from afternoon" and 
 defining in terms of use." On the other hand, they 
 present data which show that with the Knox Cube 
 Test and Knox Feature Profile Test, younger feeble- 
 minded children do better than older feeble-minded 
 children of the same mental age.' 
 
 Chotzen, who made a similar comparison between 
 the older and the younger feeble-minded children of 
 each mental age, found a marked influence of age only 
 in the following tests: "writing from copy, "writing 
 from dictation," "reading for two memories" and 
 naming the days of the week." A slight influence of 
 age was found in the case of the following; three com- 
 
 ' Pintner and Paterson: The factor of experience in inteUigenee 
 testing, The Psych. Clinic, 9: 1915, pp. 44-50. 
 
142 STANFORD REVISION OF BINET-SIMON SCALE 
 
 mands," "counting backwards, and repeating 16 syl- 
 lables.' ' It will be noted that those that showed marked 
 influence of age are all tests which relate largely to 
 matters of information, particularly school informa- 
 tion. According to Chotzen's data, age, apart from 
 intelligence, plays no part in the case of tests "that 
 demand abiUty to judge and to combine, or with such 
 as make severe demands upon comprehension, such as 
 comparison, problem-questions, noting omissions, or 
 repeating five digits."' 
 
 Wallin compared epileptics above and below 21 
 years of age with respect to the following tests: time 
 of naming four colors, time of reading B.-S. selection, 
 memories from reading B.-S. selection, time of nam- 
 ing 60 words, and time for solving the Goddard form 
 board. = No important difference was found except 
 in the case of one or two tests. Epileptics above 21 
 were superior with respect to time required for reading 
 the selection, but those below 21 retained more mem- 
 ories. In the form-board test, the younger subjects 
 were a Uttle superior to the older. Wallin concludes 
 that common age standards can be used, without much 
 error, for both subnormal children and subnormal 
 adults. 
 
 It is hard to summarize the foregoing studies, be- 
 cause their data are not wholly comparable. The 
 subjects of Wallin were epileptics and were grouped 
 for comparison into those below and those above 21 
 years of age. The subjects of Kuhlmann, Chotzen, 
 and Pintner and Paterson were all feeble-minded, but 
 
 * F. Chotzen: Die Intelligenzprufungmethode von B.-S. bei sehwach- 
 sinnigen Kindem., Zeit. f. Ang. Psych., 6: 1912, pp. 411-494. See 
 especially p. 453. 
 
 ° J. E. W. Wallin: The Binet-Simon tests in relation to the factors of 
 experience and maturity, The Psychological Clinic, 8: Feb., 1915 26&- 
 271. 
 
VALIDITY OF THE INDIVIDUAL TESTS 143 
 
 were grouped differently by age. Pintner and Pater- 
 son took Age 15 as the dividing line, while Kuhlmann 
 made four groups, as follows: Ages 6-10, 11-15, 16-25, 
 16 and over. Chotzen's figures are of limited value 
 because of the small age differences among his 236 sub- 
 jects, most of whom were between 8 and 10 years old. 
 Our own comparison is between normal individuals 
 and backward groups of the same mental age. More- 
 over, only a part of the subjects of our backward groups 
 (delinquents and unemployed) were actually retarded 
 to any serious degree. Our data on the influence of 
 age jxe also limited to t&e^tests, ajboye the iniddle part 
 oFthe s cale. 
 
 Conclusions 
 
 1. The influence of the age factor on abiUty to pass 
 the tests of the Binet scale does not appear to be great 
 enough or frequent enough to affect seriously the ac- 
 curacy of the scale as a whole. 
 
 2. Tests which are significantly easier for older than 
 for younger subjects of a given mental age include the 
 following: "days of week," "months of the year," 
 "reading a selection," "writing from dictation," 
 "naming coins," "making change," "defining in terms 
 of use," "induction," "vocabulary," "physical rela- 
 tions," "problems of fact" and the "hard comprehen- 
 sion" questions. 
 
 3. Tests which are significantly harder for older 
 than for younger individuals of a given mental age 
 include: "rhymes," "six digits," "60 words," "20-22 
 syllables," "disarranged sentence," "sense of selec- 
 tion" and "fables." 
 
 Kuhlmann' s assumption that age never exerts a 
 negative influence is certainly not vahd when "age" 
 is taken in the sense in which it is here employed. 
 
144 STANFORD RE"VISION OP BINET-SIMON SCALE 
 
 However, the assumption might hold for age in the 
 sense of maturity apart from experience. The fact that 
 adults of a given mental age are inferior in certain 
 tests to unselected school children of the same mental 
 age is probably accounted for by the naore recent prac- 
 tice of school children in the type of operation called 
 for by those tests. This explanation would seem to 
 hold especially for such tests as "memory for digits," 
 "memory for sentences," "three words," "rhymes," 
 "reading for memories," "sense of selection," "fables," 
 etc. 
 
 4. With regard to memory, the data are contradic- 
 tory. Kuhlmann finds a positive influence of age for 
 "three digits" and "five digits"; Chotzen classes 
 "memory for digits" with the tests uninfluenced by 
 age, while with our own subjects age has a markedly 
 negative influence on memory for six and for seven 
 digits. In the test of "reading for memories" our 
 older subjects of a given mental age read more rapidly 
 than the younger but give fewer and less literal mem- 
 ories. The adult unemployed were especially inferior 
 to school children of the same mental age in giving 
 literal memories — a characteristic which was strikingly 
 evident also in the test of giving the sense of a selec- 
 tion heard. In the latter test the almost irresistible 
 tendency of the older subjects was to give a critical 
 reaction or comment, rather than an epitome of the 
 thought contained in the selection. 
 
 5. The data available throw little light on the influ- 
 ence of maturity apart from the influence of experience 
 which comes with increased age. It is not improb- 
 able that the influences we mention are due less to 
 maturity, as such, than to the experience incident to 
 age. 
 
VALIDITY or THE INDIVIDtJAL TESTS 145 
 
 6. With regard to the vaUdity of the tests in gen- 
 eral, the two most important criteria are: (a) increase 
 in the percentage of unselected children that pass from 
 year to year, and (&) coherency. As for the former, 
 om- data show that all the tests included ui our revi- 
 sion satisfy this criterion very well. 
 
 7. In order to test the coherency of the scale, each 
 test from V to XIV was measured against the scale as 
 a whole. The results show that all the tests, including 
 those which have been most criticised, are reasonably 
 good tests of intelUgence, although not all are of the 
 same value. 
 
CHAPTER VIII 
 
 CONSIDERATIONS RELATING TO THE FOR- 
 MATION OF AN INTELLIGENCE SCALE 
 
 The Selection of New Tests 
 
 '.- In devising tests of intelligence it is necessary to be 
 guided by certain assumptions regarding the nature of 
 intelligence. To adopt any other course is to depend 
 for success upon happy chance. However, it is im- 
 possible to arrive at a final definition of intelligence on 
 the basis of a priori considerations alone. To demand, 
 as critics of the Binet method have sometimes done, 
 that one who would measure intelligence should first 
 ascertain exactly what intelligence is, is quite un- 
 reasonable. As Stern points out, electrical mirreuts 
 were measured long before their nature was well 
 understood. Similar illustrations could be drawn 
 from the processes involved in chemistry, physiology 
 and other sciences. In the case of intelligence it may 
 be truthfully said that no adequate definition can 
 possibly be framed which is not based primarily on the 
 symptoms empirically brought to light by the test 
 method. The best that can be done in advance of 
 such data is to mak e ten tative assumptions as to the 
 possible naturej^Jntelligence ancTtECTrsubjecTThese 
 assumptions to tests wEcFwiIl"'show their correctness 
 or incorrectness. New hypotheses can then be framed 
 for further trial, and thus gradually we shall be led 
 to a conception of intelligence which will be meaning- 
 ful and in harmony with all the ascertainable facts. 
 
 146 
 
FORMATION OF AN INTELLIGENCE SCALE 147 
 
 This, in fact, was the method of Binet. Only those 
 unacquainted with Binet's more than fifteen years of 
 labor preceding the publication of his intelligence 
 scale would think of accusing him of making no effort 
 to analyze the mental processes which his tests are 
 designed to measure. It is true that many of Binet's 
 earher assumptions proved untenable, but he was then 
 always ready to acknowledge his error and to plan a 
 new line of attack. The exceptional candor and 
 intellectual plasticity which he displayed in his patient 
 researches with intelUgence tests should serve as a 
 splendid example to aU who would contribute to this 
 difficult field of psychology. 
 
 It is not our purpose to enter here into a criticism of 
 the various tentative definitions of intelligence. Among 
 the most noteworthy of such definitions, or concep- 
 tions, are those of Ebbinghaus, Binet, Meumann, 
 Stem, and Spearman. These conceptions may be 
 briefly characterized, in order, as follows: 
 
 JBinetls conception of intelUgence emphasizes three 
 characteristics of the thought process: (1) its tendency 
 to take and maintain a definite direction, (2) the 
 capacity to make adaptations for the purpose of at- 
 taining a desired end, and (3) the power of auto- 
 criticism.* 
 
 According t o Ebbing haus, the essence of intelUgence 
 lies in comprehendmgTogether, in a unitary, meaning- 
 ful whole, impressions and associations which are more; 
 or less independent, heterogeneous or even partly con-j^ 
 tradictory. " Intellectual ability consists in the elabor- - 
 
 ^ See Binet and Simon: L'intelligence des imbeciles. L'Annee psychol- 
 ogique, 15, 1909, pp. 1-147. The last division of this article is devoted to 
 a discussion of the essential nature of the higher thought processes 
 and is a wonderful example of that keen psychological analysis in which 
 Binet was so gifted. This and other conceptions of intelhgence are 
 reserved for treatment elsewhere. 
 
 f 
 
148 STANFORD REVISION OF BINBT-SIMON SCALE 
 
 ation of a whole into its worth and meaning by means 
 of many-sided combination, correction, and comple- 
 tion of numerous kindred associations. — It is an 
 activity of combination." 
 
 Meumann offers a two-fold definition. From the 
 piycKctogical point of view, intelligence is the power 
 of independent and creative elaboration of new pro- 
 ducts out of the material given by memory and the 
 senses. From the teleological point of view, it in- 
 volves the ability to avoid errors, to surmount diffi- 
 culties, and to adjust to environment. 
 
 Stem defines intelligence purely in teleological terms 
 as "the general capacity of an individual consciously 
 to adjust his thinking to new requirements: it is gen- 
 eral adaptability to new problems and conditions of 
 hfe." 
 
 Spearman, Hart and others of the English school 
 define in¥elligence as a "common central factor" which 
 participates in all the special mental activities. This 
 factor is explained in terms of a psycho-physiological 
 hypothesis of "cortex energy," "cerebral plasticity," 
 etc. 
 
 These conceptions are only to a slight extent con- 
 tradictory or inharmonious. They differ mainly in the 
 point of view from which they are framed and in the 
 location of emphasis. Doubtless each expresses a 
 part of the truth and no one all of it. In devising new 
 tests it is well to keep in mind all of these conceptions 
 and others as well. We may thus be spared much 
 fruitless testing of mental processes which are little 
 concerned in intelligence. All the conceptions given 
 agree in locating intelUgence chiefly among the higher 
 and more complex processes, as distinguished from the 
 elementary and simple. Tests of sensory discrimina- 
 
FORMATION OF AN INTELLIGENCE SCALE 149 
 
 tion, reaction, time, etc., have proved themselves all 
 but valueless in the measurement of intelligence. 
 Seashore' s suggestion that in order to avoid influences 
 of training we should seek for intelligence tests among 
 processes which matiu-e so early as not to show age 
 differences after the early years of childhood, finds no 
 warrant in any of the published results of intelligence 
 testing. 
 
 When a test is found which from inspection appears 
 capable of bringing to Ught individual differences in 
 the mental traits involved in any reasonable concep- 
 tion of intelligence, it should be tried. As we have 
 already indicated, the best way to do this is to apply 
 the test to a large number of unselected children of 
 different ages. If the percentage of success increases 
 but little or not at all with age, the test may as well 
 be discarded. On the other hand, if the proportion 
 of successes increases significantly with age, then the 
 test is a .valid measure of intelligence unless the increase 
 is due to maturity or experience apart from intelligence. 
 To ascertain whether intelh gence, rather tha n maturity 
 or'experience,~is^sponsible for t he increase it is nec es- 
 sary to compare the intelligence of those children of a 
 given age who p agsjytiCJEestlmtlObglintgttggm of 
 fhilHrpn of t.Vift j^TTift^fl.gft who fail it. This comparison 
 Isreadily made^if an intelligence scale is available which 
 is known to have a certain degree of validity. It is the 
 method we have employed in the preceding chapter. 
 When no such scale is available for comparative pur- 
 poses we can still check up the validity of a test by 
 utiUzing school records, teachers' estimates of the 
 children's intelligence, and other criteria. It is perhaps 
 always best to use those criteria in addition to meas- 
 uring the individual test against an existing scale. 
 
150 STANFORD REVISION OF BINET-SIMON SCALE 
 
 It ggg^pgt .be too strongly emnhasized. hogever, 
 tKaTa test may under ideal laboratory conditions be 
 a valid measure of intelligence and yet not be usable 
 under the limitations of time and equipment which 
 
 usually prevail in Binet testing. To. be sddeljL§.'Sry:ice^_ 
 
 jible a test should demand only the simplest material 
 or apparatus, should require at most but a few minutes 
 of time, and should lend itself well to imiformity of 
 procedure in application and scoring. 
 
 The Assembling of Tests into a System 
 
 The Binet scale has often been criticised as a hetero- 
 geneous aggregation of tests without plan or system. 
 This criticism is based on the assumption that the only 
 way to measure intelligence is first to measure separ- 
 ately the individual mental functions involved in 
 intellectual processes and then to summate the results. 
 It would thus be necessary to have separate scales for 
 such functions as accuracy of perception, memory, 
 logical association, reasontag, judgment, etc., or pos- 
 sibly several scales for each one of these functions, in 
 order to measure its efficiency with different kinds of 
 material. 
 
 From this point of view, the Binet scale is indeed a 
 "motley array" of tests. Although there are several 
 memory tests, no effort is made thoroughly to test any 
 kind of memory. There are three tests that involve 
 drawing with pen or pencil, but there is no pretense of 
 testing thoroughly any particular functions involved 
 in drawing from copy or memory. The same may be 
 said of various tests of association, mastery of lang- 
 uage, comprehension, reasoning, etc. JHqw-,— it -is^ 
 often asked, can the scale measure intSiigence as a 
 whole when it offers no reliable, measure of any single 
 aspect of intelligence? 
 
FORMATION OF AN INTELLIGENCE SCALE 151 
 
 This is the point of view of "faculty psychology," 
 which, far from being defunct, has really given direc- 
 tion to much of the current work in intelligence test- 
 ing. It was the point of view which long controlled 
 the work of Binet, who, like others, began by attempt- 
 ing to get at intelligence by measuring memory, at- 
 tention, sense discrimination and other individual 
 functions. Jt jwas^^only^ ^.fter years of exploration 
 along the^old_ lines that, he Anally broke .away^rom 
 "them and undertook, so to speak, to triangulate the 
 height of the tower without first getting the dimen- 
 sions of the iadividual stones which made it up. The 
 assumption that it is easier to measure a part, or one 
 aspect, of intelligence than all of it, is fallacious in 
 that the parts are not separate parts and can not be 
 separated by any refinement of experiment. They 
 are interwoven and intertwined. Each ramifies every- 
 where and appears in all other functions. The analogy 
 of the stones of the tower does not really apply. Mem- 
 ory, for example, cannot be tested separately from at- 
 tention, or sense discrimination separately from the 
 associative processes. After vainly trying to disen- 
 tangle the various intellective functions Binet decided 
 to test their combined functional capacity without any 
 pretense of measuring the exact contribution of each 
 to the total product. IntelUgence tests have been 
 successful just to the extent to which they have been 
 guided by this aim. 
 
 Memory, attention, imagination, etc., are terms of 
 structural psychology ._ Binet's psychology is dynamic . 
 He conceives intelUgence as the sum total of those 
 thought processes which consist in adaptation. This 
 adaptation is not explicable in terms of the old mental 
 faculties. No one of these "faculties" can explain a 
 
 v\.= 
 
152 STANFORD REVISION OF BINET-SIMON SCALE 
 
 single thought process, for such process always in- 
 volves the participation of many "faculties," whose 
 separate r6les are impossible to distinguish accurately. 
 Instead of measin-ing the intensity of various mental 
 states (psycho-physics), it is more enlightening to 
 measure their combined effect on adaptation. Using 
 a biological comparison, Binet says the old "faculties" 
 correspond to the separate tissues of an animal or 
 plant, while his own "scheme of thought" corres- 
 ponds to the functioning organ itself. Binet' s psy- 
 chology was a functional rather than a stru ctural 
 psycholoj^.2 
 
 TBinet's conception of "general intelUgence," although 
 expressed in psychological terms, harmonizes well with 
 Spearman and Hart's psycho-physiological conception 
 of intelligence as depending upon general cerebral 
 efl&ciency, or "cortex energy." The assumption is 
 common to both that a common factor, "intelligence" 
 (Binet) or "general ability" (Spearman), enters into 
 every specific mental performance of an individual, 
 and that by testing a subject with a large variety of 
 mental tasks the special factors involved are canceled 
 and the general factor revealed. If Binet's theory of 
 intelligence is valid, we must reject those criticisms 
 which condemn the scale for its failure to test out and 
 follow up individual mental functions from childhood 
 to maturity. The incorporation in the scale of hetero- 
 geneous tests and the partial lack of consecutiveness 
 in their arrangement were the result, not of accident, 
 but of a well-defined theory. Whether the underly- 
 ing theory is correct, is a matter to be determined by 
 patient research. 
 
 2 See Binet and Simon: L'intelligence des imbeciles, L'Annee Psy- 
 chologique, 15, 1909. Especially pp. 143-147. 
 
FORMATION OF AN INTELLIGENCE SCALE 153 
 
 It is unfortunate that off-hand criticisms of the 
 Binet method have been so confidently voiced by psy- 
 chologists who have evidently not taken the trouble to 
 acquaint themselves with Biaet's work. One of these 
 criticisms is to the effect that since the tests of suc- 
 cessive years in the scale do not follow up the same 
 functions, the different "mental ages" are therefore 
 not comparable; that we do not know, for example, 
 how a child of Mental Age VIII differs from one of 
 Mental Age VI, since the two mental ages have not 
 been earned by tests of the same functions. The 
 criticism impUes that "mental age," in terms of the 
 Biaet scale, is meaningless. We would urge, however, 
 that whether the different mental ages have meaning 
 and are comparable is a question which can only be 
 settled experimentally. We have already shown 
 (Chapters III and VI) that the evidence strongly sup- 
 ports the validity of the Binet method. Knowing 
 that a given child of 6 years has a mental age of 5 
 years by the Biaet scale, we are able to forecast fairly 
 accurately the mental age the child will have at 12 
 years, and even the probable degree of his school 
 success. The proof of the Binet method is in the fact 
 that it works so well. Investigation alone will de- 
 termine whether a scale made up on the plan advocated 
 by Rossoluno, Thomdike, Yerkes and others (that is, 
 a scale designed to follow up and measure individual 
 functions separately) is capable of furnishing an in- 
 dex of intelligence any more reUable or any more 
 meaningful for purposes of age comparison than that 
 secured by the Binet scale. Indeed, it is conceivable 
 that a scale whose various year-groups of tests were 
 composed with studied effort to make them dissimilar 
 and non-comparable might still give intelligence 
 
154 STANFORD REVISION OF BINET-SIMON SCALE 
 
 quotients of high vaUdity at the different ages. It is 
 to be hoped that someone will make such an experi- 
 ment. 
 
 Whatever the facts may prove to be, it is probably 
 desirable for the present to include several varieties 
 of tests in each year group, and as far as possible to 
 avoid extreme dissimilarity in the general character of 
 the tests of successive years. It may even be desir- 
 able, when it is convenient, to have the same test or 
 the same type of test recur at different age levels. 
 Binet, himself, frequently followed this plan. It is not 
 at all certain, however, that it is necessary for the pur- 
 pose of measuring general intelUgence to go much 
 farther than did Binet in the direction of testing out 
 the special mental functions. 
 
 The Location and Scoring of Tests 
 
 The percentage of correct responses necessary for 
 locating a test is a much-debated question. Binet's 
 standard was a shifting one, varying from^CL±£u9£L. 
 percent according to the upward trend of the curve for 
 the test in question. Goddard, Kuhhnann, Bobertag, 
 Stem and Meumann adhere strictly to the 75 percent 
 standard. Bobertag and Stem seek to justify this 
 standard by the (supposed) fact that it gives a fairly 
 normal distribution of mental ages and causes ap- 
 proximately 50 percent to test "at age," that is, within 
 12 months of normal. It is true that the 75 percent 
 standard has this effect at a certain part of the scale. 
 It is evident, however, from the data presented in 
 Chapter III, that the relation between the 75 percent 
 standa,rd and the 50 percent testing "at age" is a 
 purely accidental one. That it should hold at any 
 point is due to the chance ratio that obtains for a 
 
FORMATION OF AN INTELLIGENCE SCALE 155 
 
 certain period between chronological age and the rate 
 of growth. There can be no correct scale which will 
 cause 60 percent of unselected children to test "at 
 age" at all the age levels. If the scale is accxorate it 
 appears that the proportion of "at age" cases among 
 4-year-olds wiU be about twice as great as among 8- 
 year-olds and about three times as great as among 12- 
 year-olds. That is, the curve of distribution of mental 
 ages of unselected children becomes more and more 
 flattened as we ascend to the higher age groups. 
 
 This last statement is only another way of expressing 
 the familiar fact that, relative to the mental develop- 
 ment already attained, a year of growth amounts to 
 less in the upper than in the lower years. A year of 
 mental growth added to the mental age of 5 years 
 amounts to an increase of 20 percent, while a year 
 added to the mental age of 10 years is an increase of 
 only 10 percent. Jt-is-evidentr-thfirfifore^ that if a 
 scale contains a group of tests at each age level, these 
 groups become progressively closer together up the 
 scale, until finally, when the point of mental maturity 
 has been attained, the successive age groups are not 
 separated at all. The distance between the 5-year and 
 6-year tests is as great as that between the 10-year and 
 12-year tests, and 21-year tests are probably not 
 separated from 20-year tests by any distinguishable 
 distance whatever. 
 
 This crowding up of the age levels in the upper 
 years is of greatest significance as regards the per- 
 centage of passes necessary for locating tests in a 
 scale like the Binet, for it^mea ns tha t tJifi. true-standard, 
 percen tage is not uniform for the different age JeYfils, 
 but variable. This will be evident if the following 
 facts are borne in mind: 
 
 \i>. 
 
156 STANFOED REVISION OF BINET-SIMON SCALE 
 
 1. A child does not earn a given mental age, say 8 
 years, by his performances on the tests of the 8-year 
 group alone. He earns it by certain successes in the 
 8-year group, plus certain successes in the succeeding 
 year-groups, minus certain failures in the preceding 
 year-groups. 
 
 2. Since the year-groups above the given mental 
 age are relatively closer together than the year-groups 
 below that mental age, it is evident that if the tests of 
 all the different age-groups are located according to the 
 same standard (say 75 percent of passes), then imse- 
 lected children of any given age will, on the average, 
 attain more successes above their age than they will 
 suffer failures below their age. 
 
 3. In testing unselected children of the various ages 
 with a scale of this kind (that is, a scale having an 
 equal number of tests at each age and aU tests located 
 according to a uniform standard) the ratio between (a) 
 the successes above a given age attained by the children of 
 that age and (b) the failures below that age suffered by the 
 same children can not be exactly the same at any two age- 
 levels. This would cause a displacement, and an im- 
 equal displacement, of median mental age from median 
 chronological for the children of the upper age-levels. 
 
 4. It must be especially borne ia mind, that the 
 guiding principle in the formation of an accurate scale 
 is that the median mental age must coincide with median 
 chronological age for unselected children of each age. 
 
 There are three ways of overcoming these difi&culties 
 so as to bring it about that median mental age will 
 coincide with median chronological age: (1) the num- 
 ber of tests in the upper age-groups may be progres- 
 sively reduced, (2) the tests of the upper age-groups 
 may be located on the basis of a smaller and smaller 
 
 percent passing; nr CR^ t.Tl p twn mpthorlg mair Ko mrr,- 
 
 bined. 
 
FOEMATION OF AN INTELLIGENCE SCALE 157 
 
 Binet's 1911 revision meets the situation ia part by- 
 omitting certain year-groups of tests altogether. The 
 upper tests of both the 1908 and 1911 series are also 
 somewhat harder for the age in which they occur than 
 are the tests at the lower end of the scale, though this 
 was probably imintentional. The diflS.culty can really 
 not be satisfactorily solved by a progressive reduction 
 ui the number of tests, since tests can only be dropped 
 by wholes. In certain cases, to retain a test would 
 give too much advantage in one direction, while to 
 dropL it would throw too much weight in the opposite 
 direction. 
 
 In the Stanford Revision we have fewer tests per 
 year in the upper part of the scale than in the lower, 
 but we have not attempted to make the decrease 
 perfectly gradual. Instead, whole year-groups have 
 been omitted. This irregularity was then remedied 
 empirically ia three ways: (1) the number of tests in 
 Group XII was increased to eight; (2) higher values 
 were assigned to the tests of the "average adult" and 
 "superior adult" groups; and (3) tests were located in 
 the upper groups on the basis of a smaller percent 
 passiag. Changes along these lines were continued 
 until an arrangement was found which caused the 
 median mental age of unselected children of any age 
 to coincide approximately with median chronological 
 age. When the tests had been arranged in such a way 
 as to bring this about, it was found that they were 
 passed by the following percents in the locations as- 
 signed them.' 
 
 2 The percents from IV to XIV, incluaive, are those found for Stan- 
 ford unselected cases in 1914r-1915. As unselected cases were not 
 available for the "average adult" and "superior adult" tests, the figures 
 for those were obtained by taking the arithmetical average of the 
 percents for the high-school pupils, the business men, Wilhams' de- 
 . linquents of the "average adult" level and Knolhn's unemployed of 
 the same level. The resulting figure presumably shows what " average 
 adult" inteUigence can do with the tests of the "superior adult" group. 
 
158 STANFORD REVISION OF BINET-SIMON SCALE 
 TABLE 43 
 
 Year 
 
 Average Percent 
 
 Year 
 
 Average Percent 
 
 Group 
 
 Passing 
 
 Group 
 
 Passing 
 
 IV 
 
 77 
 
 IX 
 
 62.3 
 
 V 
 
 71.3 
 
 X 
 
 64.5 
 
 VI 
 
 70.8 
 
 XII 
 
 62.4 
 
 VII 
 
 68 
 
 XIV 
 
 55.6 
 
 VIII 
 
 63.2 
 
 "Av. Adult" 
 
 59.8 
 
 
 
 "Sup. Adult" 
 
 37.4 
 
 The percents are the averages for the regular tests 
 only; the alternates are omitted. The figure for XIV 
 does not include the clock problem, owing to a change in 
 the method of scoring employed in the revision, and 
 in "superior adult" the test of repeating seven digits 
 backward is not taken ino accoimt for lack of suf- 
 ficienct data. 
 
 It will be noted that from IV to IX there is a general 
 decrease in the average percent of passes for the tests 
 of successive year-groups. This is what we should 
 expect from the facts set forth. Beyond IX, however, 
 the percents vary more or less irregularly, owing to 
 the omission of XI, XIII, XV, etc. The omission of 
 XI must also affect the placing of tests in IX and X. 
 If tests were included at XI, then the tests of IX and X 
 would either have to be made harder or else shifted 
 downward in order to keep the median mental ages 
 at these levels from running too high. 
 
 It is evident that the percents beyond VIII have no 
 appUcability or meaning apart from the present scale 
 as it is actually constituted. A scale constructed 
 somewhat differently, with more or fewer groups of 
 tests in the upper ranges, or with slightly different 
 values assigned to the tests of the different year-groups, 
 would require other percents for the correct location 
 
FORMATION OF AN INTELLIGENCE SCALE 159 
 
 of the tests. Similarly, the percents below IX would 
 lose general significance if any of the year-groups were 
 omitted. As stated elsewhere, we have not been 
 guided by theoretical considerations in locating the 
 tests, but by the one purpose of securing an arrange- 
 ment which would give median mental ages as nearly 
 as possible equal to the median chronological ages. 
 Although we have endeavored to keep the tests of a 
 given age-group as nearly as possible of- the same 
 difl&culty, it must always be remembered that the 
 correct location of a test does not depend wholly upon 
 the percent that pass it any one year. 
 
 It would be much more satisfying if the difficulties 
 of the age-grade method could be disposed of on the 
 basis of purely logical considerations, without the 
 necessity of trial and error. The problem is so in- 
 volved, however, that such a solution is not easy. 
 For example, to make a correct scale by reducing in 
 exactly the right proportion the munber of tests in 
 the upper years, or by introducing a variable standard 
 for locating the tests in the different year-groups, 
 would be impossible on logical consideration s, unles s 
 we ha d ex act knowledge as to the normal rate of 
 growth at every point . 
 
 TPwouI3"doubtiess" be possible to construct an in- 
 telligence scale by a method based purely on logical 
 consideration. Mr. Otis* has formulated such a plan 
 which involves, among other features, the location of 
 each test at the age where it is passed by 50 percent 
 of unselected children. However, Mr. Otis' sugges- 
 tions are hardly applicable to a scale like that of Binet 
 and so need not be set forth here. 
 
 * In a thesis on "The logical and mathematical aspects of intelligence 
 testing by the Binet method," Psychological Review, March and May, 
 1916. 
 
160 STANFORD REVISION OF BINET-SIMON SCALE 
 
 Point Scales 
 
 \C^ YerJ^es h as strongly emphasized the advantages of a 
 
 yy^ "pomt scale as contrasted with the age-grade method 
 
 /^ of Binet. Three advantages are claimed for the point 
 scale: (1) that it becomes better standardized, the 
 more widely it is used, however much the results se- 
 cured lack agreement; (2) that the point scale admits 
 of more ready comparison of intelligence norms of the 
 sexes, different races, and the various social classes; 
 (3) that it more conveniently permits the giving of 
 partial credit for partial success in a test. 
 
 These claims are less valid than they at first appear. 
 In the first place, the lack of agreement in Binet data 
 is unquestionably due in large measure .toJack-flLuois. 
 ^fomitx^oLEIQcediixe in giving and scoring the tests, 
 that is, to sources of error which are no more avoidable 
 in the use of a point scale than any other. We have 
 tried to remedy this defect for the Binet scale by pre- 
 paring a very detailed guide. 
 
 In the second place, it can not be admitted that the 
 Binet norms necessarily become more insecure or 
 "muddled" with the accumulation of data collected 
 by satisfactory procedure. Such data can, in fact, be 
 readily utiUzed for piuposes of revising the scale from 
 time to time. Another way would be to let the scale 
 stand, admittedly imperfect as it is, but to make use 
 of all available results for correcting the intelligence 
 quotients which the scale gives at each age. If it 
 shoiild be found, for example, that the present revi- 
 sion gives for an indefinitely large number of unselected 
 6-year-olds a median intelligence quotient of 103, 
 instead of the desired 100, it wquld^then„ba,jnerely 
 necessary to use 103 as the ju)rmJjistead.jQl,,3L00^ 
 Similarly with an error in either direction at any other 
 age. 
 
FORMATION OF AN INTELLIGENCE SCALE 161 
 
 Finally, as shown in Chapter III and as is implied 
 above, the Binet method becomes itself a point scale 
 as soon as we express intelligence status in terms of 
 the intelligence quotient. In terms of its "points" 
 (that is, units of intelligence quotient) we may com- 
 pare sexes, races or social classes as readily as by any 
 other point scale. Moreover, the "points" of the 
 Binet scale are more nearly equal units than can pos- 
 sibly be the case with a point scale whose various 
 tests have had point values assigned to them ia an 
 arbitrary and off-hand manner. ^ 
 
 The question whether a scale to be vaUd must give 
 partial credit for partial success in a test is another 
 aspect of the question whether it is necessary for the 
 tests to follow up the development of individual func- 
 tions. In addition to what we have already said on 
 this matter it may be pointed out that it is impossible 
 entirely to avoid the "all or none" principle in scoring. 
 A subject who is being tested even by the Yerkes- 
 Bridges scale will in many cases lose "points" because 
 his abiUty ia the fimction tested falls just a little short 
 of that necessary to earn the credit assigned to the test, 
 or part of a test. There is one real advantage, how- 
 ever, in giving as far as it is convenient to do so, 
 partial credit for partial success; it makes it possible 
 to get along with a somewhat smaller number of tests. 
 By following this method, as we have done with the 
 tests of vocabulary, fables, ball and field, etc., we may 
 make a single test serve as two or three, or even more 
 tests. 
 
 ' See Arthur S. Otis: A criticism of the Yerkes-Bridges point scale, 
 with alternative suggestions, Journal of Educational Psychology, March, 
 1917. 
 
xC 
 
 162 STANFORD REVISION OF BINET-SIMON SCALE 
 
 / ^ Summary 
 
 / 1. In the selection of intelligence tests it is neces- 
 sary to be guided by a tentative conception as to the 
 nature of the processes to be measured. It is unreason- 
 able, however, to demand that intelUgence testing 
 wait upon a complete definition of intelligence. Such 
 a definition can be arrived at only empirically, by the 
 use of tests which bring to light the symptoms of in- 
 telligence. 
 
 2. Many of the criticisms of the Binet method are 
 based on an unfortunate lack of acquaintance with 
 Binet's psychological work and of the considerations 
 which shaped his system of tests. Whether the age- 
 grade method is inferior to the "profile" method, or 
 what we might call the "special function" method, 
 can be answered only in the light of future researches. 
 
 3. In a system like that of Binet there is no single 
 standard as to the percentage who should pass a test 
 in a given year in order to determine its location in 
 that year. Factors involved are: (1) the relative 
 amount of mental growth from year to year, and (2) 
 the number and weighting of tests at the upper levels. 
 
 4. The advantages claimed for the point-scale 
 method are questionable. The most important con- 
 sideration in framing such a scale, namely, that of 
 equalizing the "points," has been overlooked. We 
 have tried to show that the Binet scale itself, properly 
 standardized, becomes automatically a point scale not 
 easily improved upon. 
 
APPENDIX I 
 The Data Utilized in the Stanford Revision 
 
 All of the 2060 tests were made by trained examiners, with the ex- 
 ception of about a fourth of the Terman-ChUds cases. As explained 
 in the text, the Terman, Lyman, Galbreath, Talbert, and Cuneo sub- 
 jects were within two months of a birthday and were as nearly as pos- 
 sible unselected. The Terman and Childs subjects were drawn from 
 social classes perhaps sUghtly above the average, though this was not 
 fully reaUzed at the time the tests were made. The Terman, Trost 
 and Waddle cases were tested in a trial of the Terman-Childs Tentative 
 Revision of 1912. Of the 310 in the latter group, 50 were tested by 
 Dr. Charles Waddle, State Normal School, Los Angeles, California, 
 125 by Miss Helen Trost, a student at Stanford University, and the 
 remaining 135 by Terman. They were probably of about average 
 social status. Effort was made to avoid selection, but the precautions 
 taken to this end were not adequate. 
 
 The following tables give the percentage that passed each test at 
 each age. Where statistics are given, it will be understood that all, 
 or practically all, of the subjects of the age in question were given the 
 test. A few tests, owing their improper location in the trial series, 
 were not given to all the subjects to whom they should have been given, 
 and in such cases the percents coiHd not be tabulated for the desired 
 range of ages. 
 
 Terman's high-school students were from 17 to 20 years of age, were 
 members of the junior and senior classes, and were all doing school 
 work of about average quaUty. 
 
 Dr. WiUiams' delinquents were inmates of the Whittier State School, 
 one of the three juvenile reform schools of Cahfomia. It should be 
 noted that the statistics for WiUiams' delinquents and KnoUin's un- 
 employed are based on the classification of these subjects by mental 
 age. 
 
 The Hopwood and Houser vocabulary tests were mass (written) 
 tests of pupils from the fourth to the eighth grades in Alameda and 
 Riverside, California. Approximately 30 pupils were tested at each 
 age indicated in each of these series. The Terman vocabulary data 
 from college students were also collected by mass (written) tests. The 
 students numbered 65 and belonged chiefly to the junior and senior 
 
 Since the above data were collected, additional tests have been made 
 of 250 unskilled, semi-skilled, and skilled employees, 160 prisoners, 
 300 additional juvenile delinquents, 130 high-school students, 80 chil- 
 dren in an orphanage, 100 kindergarten children, 200 first-grade children, 
 250 children in other grades, about 100 superior children, 174 children 
 suspected of being feeble-minded, and 140 special-class children. Re- 
 tests have also been made of nearly 150 children tested by Terman and 
 Childs. The results of these investigations will be published in another 
 monograph. 
 
 163 
 
164 STANFORD REVISION OF BINET-SIMON SCALE 
 DATA UTILIZED IN THE STANFORD REVISION 
 
 
 
 
 
 
 
 Number at Each Age 
 
 
 
 
 
 Source of Data 
 
 3 
 
 4 
 
 5 
 
 6 
 
 7 
 
 8 
 
 9 
 
 10 
 
 11 
 
 12 
 
 13 
 
 14 
 
 15 
 
 16 
 
 Total 
 
 Terman, 
 
 Lyman, 
 
 Galbreath, 
 
 Talbert, 
 
 Cuneo. 
 
 Terman and 
 Childs. 
 
 Terman, 
 Trost, and 
 Waddle. 
 
 10 
 
 17 
 29 
 
 S 
 
 54 
 83 
 
 10 
 
 117 
 26 
 
 22 
 
 92 
 29 
 
 39 
 
 100 
 43 
 
 44 
 
 113 
 49 
 
 34 
 
 87 
 33 
 
 55 
 
 79 
 44 
 
 36 
 
 83 98 
 
 3517 
 
 1 
 25 22 
 
 82 
 6 
 
 18 
 
 46 
 2 
 
 10 
 
 14 
 
 7 
 
 992 
 396 
 
 310 
 
 Terman's high- 
 school pupils. 
 
 Knollin's business 
 men. 
 
 KnoUin's imem- 
 ployed men. 
 
 Williams' juvenile 
 delinquents. 
 
 (Ages 16-21. Junior and senior classes.) 
 
 (Ages 25-65 years. Had not attended the 
 high school.) 
 
 ("Hoboes," ages 21-60.) 
 
 (Ages mostly 14-21.) 
 
 32 
 
 30 
 
 150 
 
 ISO 
 
 
 
 2060 
 
 Pekcents That Passed Individtjaii Tests in Different Stanford 
 Investigations 
 
 (Figures at top of each column refer to ages) 
 
 IIP Parts op the Body 
 
 3 4 5 6 
 
 Terman, Lyman, Ordahl, etc. 80 86 100 100 (Nose, eyes, mouth, hair, 3 of 4) 
 
 Terman and Childs 89 96 100 (Nose, eyes, mouth, 3 of 3) 
 
 Terman, Trost, Waddle 100 100 100 (Nose, eyes, mouth, 3 of 3) 
 
APPENDICES 165 
 
 III' Naming Familiar Objects 
 3 4 5 6 
 Tennan, Lyman, Ordahl, etc. 90 100 100 100 (Key, penny, knife, watch, pen- 
 
 cU, 4 of 4) 
 
 Terman and Childs 93 100 100 (Key, penny, knife, 3 of 3) 
 
 Terman, Trost, Waddle 100 100 100 (Key, penny, knife, 3 of 3) 
 
 IIP Pictures, Enumeration 
 3 4 5 6 
 Terman, Lyman, Ordahl, etc. 80 94 100 100 
 
 Tennan and Childs 96 100 100 
 
 Terman, Trost, Waddle 100 100 100 
 
 IIP Giving Sex 
 
 3 4 5 6 
 Terman, Lyman, Ordahl, etc. 80 94 100 100 
 
 Terman and Childs 100 100 100 
 
 Terman, Trost, Waddle 100 100 100 100 
 
 III' Giving Family Name 
 3 4 5 6 
 Terman, Lyman, Ordahl, etc. 80 94 100 100 
 
 Terman and Childs 95 100 100 
 
 Tennan, Trost, Waddle 75 100 100 
 
 III« Repeating 6-7 Syllables 
 3 4 5 6 
 Terman, Lyman, Ordahl, etc. 70 94 100 100 
 
 III Alternative. Three Digits 
 3 4 5 6 
 Terman, Lyman. Ordahl, etc. 70 87 100 100 
 
 Terman and Childs 97 100 100 
 
 Terman, Trost, Waddle 100 75 100 100 
 
 rV' Comparison of Lines 
 3 4 5 6 
 
 T., L., O., etc 60 85 97 99 
 
 T. and C. 100 100 100 
 
 IV' DlSCRIMINATIGNS OP FORMS 
 
 3 4 5 6 ---^■' 
 
 T.,L.,0.,etc 10 70 83 95 
 
 rV' Counting Four Pennies 
 3 4 5 6 
 
 T.,L.,0.,etc 20 77 93 98 
 
 T. ani C. 91 90 100 
 
 T , T , W 80 100 100 
 
166 STANFOED REVISION OF BINET-SIMON SCALE 
 
 IV* Copying Sqttarb 
 3 4 5 6 
 
 T., L., O., etc 10 71 76 95 (Pencil, 1 of 3) 
 
 T. andC 86 91 95 (PencU, 1 trial only) 
 
 T., T., W 60 88 100 (Pencil, 1 trial only) 
 
 IV COMPKEHBNSION, IbT DEaBBE 
 
 3 4 5 6 
 T., L., O., etc 40 82 93 96 
 
 IV' Repeating Four Digits 
 3 4 5 6 
 T., L., O., etc 40 76 83 91 
 
 IV Altbenative. 12-13 Stleableb 
 
 3 4 5 6 
 
 T., L., O., etc 30 83 85 91 (12-13 syUables, 1 of 3) 
 
 T. andC 51 83 85 (14 syllables, 1 of 1) 
 
 T., T., W 60 75 91 (12-14 eyUables, 1 of 3) 
 
 V Comparison or Weights 
 
 4 5 6 7 
 
 T., L., O., etc '....50 70 94 96 (3-15 grams, 2 of 3) 
 
 T. and C 97 98 95 100 (3-12, 6-15 grams. Both cor- 
 rect, but 2nd trial allowed) 
 T., T., W 60 88 100 100 (3-12. 6-15 grama, 2 of 3) 
 
 V^ Naming Four Colors 
 
 4 5 6 7 
 
 T., L., O., etc 59 74 86 97 
 
 T. andC 65 74 84 96 
 
 T., T., W 50 88 95 97 
 
 V Aesthetic Comparison 
 
 4 5 6 7 
 
 T., L., O., etc 64 73 94 96 
 
 T. andC 80 88 83 90 
 
 T., T., W 60 86 90 98 
 
 V* DBFiNrrioNS — Use or Better 
 4 5 6 7 
 
 T., L., O., etc 51 69 92 98 (Ball, fork, table, chair, horse, 
 
 _ J „ pencil, 4 of 6) 
 
 T. and C 86 91 83 90 (Fork, table, chaii, horse, 
 
 T., T., W 60 100 100 100 (Like Terman SLudCUm °^ ^^ 
 
APPENDICES 167 
 
 V Patience, or Divided Rectangle 
 4 5 6 7 
 
 T., L., O., etc 21 70 92 95 (2 of 3. 1 minute each) 
 
 T. amdC 70 88 95 100 (2 of 3. No time limit) 
 
 T., T., W , 50 75 90 (2 of 3. 1 minute each) 
 
 V Three Commissions 
 3 4 5 6 7 
 
 T., L., O., etc 20 50 72 91 93 (Order must be correct) 
 
 T. and C 72 81 87 95 (Correct order not required) 
 
 T., T., W 50 80 94 95 (Correct order) 
 
 V Alternative. Givinq Age 
 
 3 4 5 6 7 
 
 T., L., O., etc 50 76 92 98 
 
 T. andC 72 79 96 95 
 
 VII Right and Left 
 
 4 5 6 7 8 
 
 T., L., O., etc 40 50 71 86 95 (3 of 3, or 5 of 6) 
 
 T. andC 41 73 75 90 93 (Like Binet) 
 
 T., T., and W 25 63 62 72 90 (Like Binet) 
 
 VP Mutilated Pictures 
 4 5 6 7 8 
 
 T., L., 0., etc 27 50 65 87 96 
 
 T. andC 34 48 57 68 82 
 
 T., T., andW 12 33 74 86 97 
 
 VI' Counting Thirteen Pennies 
 4 5 6 7 8 
 
 T., L., O., etc 30 46 76 93 96 
 
 T. and C 55 74 100 100 
 
 T., T., andW 25 67 92 94 
 
 VP Comprehension, 2nd Degree _______ 
 
 4 5 6 7 8 
 
 T., L., O., etc 25 55 70 86 93 
 
 VI^ Naming Four Coins 
 4 5 6 7 8 
 
 T., L., O., etc 25 47 74 91 95 
 
 i T. and C. 19 41 69 93 100* 
 
 T., T.,andW 25 81 95 98 
 
 I 
 
 * Re-scored by new standard. Figures in original article allowed no error. 
 
168 STANFORD REVISION OF BINET-SIMON SCALE 
 
 VI« Repeating 16-18 Syllables 
 
 4 5 6 7 8 
 
 T., L., O., etc 34 56 69 90 95 (1 of 3 correct, or 2 with 1 error 
 
 each) 
 
 T. andC 31 53 62 80 (1 of 3 without error) 
 
 T., T., andW 38 67 77 86 (1 of 3 without error) 
 
 VI Alteknativb. Forenoon and Afternoon 
 4 5 6 7 
 
 T., L., O., etc 46 60 82 97 
 
 T. andC 65 84 87 100 
 
 T., T., andW 51 68 88 95 
 
 VII' Number or Fingers 
 
 5 6 7 8 9 
 
 T., L., O., etc 24 61 72 86 95 
 
 T. and C 33 73 92 97 100 
 
 T., T., andW 25 57 80 88 98 
 
 VIP PicTCTRES — Descriptions 
 5 6 7 8 9 
 
 T., L., O., etc 27 56 63 88 97 
 
 T. andC 42 47 60 70 83 (Re-scored since 1912) 
 
 T., T., andW 23 66 77 95 100 
 
 VIP Repeating Five Digits 
 5 6 7 8 9 
 
 T., L., O., etc 34 59 74 83 93 
 
 T. andC 50 50 72 74 83 
 
 T., T., andW 26 43 74 80 88 
 
 VIP Tying Bow-knot 
 5 6 7 8 9 
 
 T., L., O., etc 11 35 69 88 94 
 
 T. andC 27 61 74 (160 school children, ages 6, 7, 8) 
 
 VII' Giving Differences 
 
 5 6 7 8 9 
 
 T., L., O., etc 23 54 66 78 90 
 
 T. and C 19 47 62 74 85 (Re-scored since 1912) 
 
 T., T., andW 30 61 74 86 91 
 
 VII' Copying Diamond 
 
 5 6 7 8 9 
 
 T., L., O., etc 4 30 64 83 94 (Pen, 2 of 5) 
 
 T. and C 16 42 67 90 98 (Pencil, 1 trial. Re-scored since 
 
 1912) 
 T., T., andW 10 48 70 82 91 (Pencil, 1 trial) 
 
APPENDICES 169 
 
 VII Alternative 1. Days of Week 
 
 5 6 7 8 9 
 
 ,L., O., etc 27 65 81 91 (No error. 2 of 3 "checks") 
 
 andC 66 85 85 98 (1 error allowed. No "checks" 
 
 used) 
 
 VII Alternative 2. Three Digits Backwards 
 5 6 7 8 9 10 
 ,, L., O., etc 2 35 60 83 90 96 
 
 VIII' Ball and Field (Inferior Plan) 
 
 6 7 8 9 10 11 12 13 14 
 
 ,, L., O., etc 37 52 60 67 73 77 82 87 90 
 
 Vni» COUNTINQ 20-0 
 
 6 7 8 9 10 
 
 ., L., O., etc 16 48 66 81 96 
 
 .andC 7 62 69 95 100 
 
 ., T., andW 19 38 57 82 97 
 
 VHP Comprehension, Third Degree 
 6 7 8 9 10 
 
 ., L., O., etc 47 59 72 85 92 
 
 .andC 38 57 69 78 85 
 
 ., T., and W 20 51 62 72 81 
 
 VHP Giving Similarities 
 6 7 8 9 10 11 ^ 
 
 '., L., O., etc 30 51 63 78 90 92 
 
 VIII' DEFmmoNs Superior to Use 
 7 8 9 10 
 
 ., L., 0., etc 43 62 71 83 (Balloon, tiger, football, soldier, 
 
 2 of 4) 
 
 .andC 34 58 77 89 (Fork, spoon, chair, horse, 
 
 mamma. 2 of 4. Re-scored 
 since 1912) 
 
 VIII' VOCABTTLARY, 20 DEFINITIONS 
 
 6 7 8 9 10 11 
 
 .,L.,0.,etc 12 56 78 97 
 
 .andC. 14 61 69 91 
 
 ., T., andW 20 24 57 86 88 
 
 :opwood* 84 90 96 
 
 :ouser* 63 80 93 98 
 
 * The tests made by Miss Margaret Hopwood and J. D. Houser, graduate 
 indents at Stanford University, were mass tests (written) on imselected chil- 
 ren in the grades. 25 to 35 were tested at each age indicated. 
 
170 STANFORD EEVISION Or BINET-SIMON SCALE 
 
 VIII Altbknativb 1. Naming 6 ComB 
 
 6 7 8 9 10 
 
 T., L., O., etc 27 40 64 88 95 
 
 T. andC 33 60 81 90 (Re-scored since 1912) 
 
 VIII Alternative 2. Whiting fkom Dictation 
 
 6 7 8 9 10 
 
 T., L., O., etc 12 53 88 96 100 (Time limit, 1 minute) 
 
 T. and C 7 79 83 100 100 (No time limit) 
 
 IX' Giving Date 
 
 7 8 9 10 11 12 
 
 T., L., O., etc 20 50 67 83 91 
 
 T. andC 25 52 81 77 87 93 
 
 T., T., andW 14 48 71 86 94 
 
 Knollin's imemployed. . . • 65 80 98 (By mental age) 
 
 IX' Arranging Weights 
 
 7 8 9 10 11 12 
 
 T., L., O., etc 7 35 58 69 75 79 (2 of 3 trials correct) 
 
 T. andC 25 29 55 54 77 (Only 1 trial given) 
 
 T., T., andW 60 71 73 82 (2 of 3 trials correct) 
 
 Williams' delinquents ... 77 86 93 (By mental age) 
 
 Knollin's unemployed. . . 70 79 (By mental age) 
 
 IX' Making Change 
 
 7 8 9 10 11 12 
 
 T., L., O., etc 3 38 60 83 92 (10-6, 15-12, 25-4, 2 of^3) 
 
 T. andC 7 26 42 55 67 (25-9. One trial) 
 
 T., T., and W 29 62 78 91 (25-4. One trial) 
 
 W's delinquents (By mental age) 85 100 98 
 
 K'a unemployed (By mental age) 95 98 100 (Note influence of age) 
 
 IX^ Repeating Four Digits Backwards 
 
 7 8 9 10 11 12 
 T., L., 0., etc 18 44 62 75 86 91 
 
 W's delinquents 46 61 73 82 (By mental age) 
 
 IX' Three Words 
 
 8 9 10 11 12 13 
 
 T., L., O., etc 44 68 81 90 95 94 
 
 T. andC 42 60 84 86 93 
 
 T., T., andW 48 68 86 91 90 90 
 
 W's delinquents 95 100 100 (By mental age) 
 
 K's unemployed 30 67 75 96 (By mental age) 
 
APPENDICES 
 
 171 
 
 IX' Finding Rhymes 
 
 , 8 9 10 11 12 13 14 
 
 T., L., 0., etc 48 62 81 83 94 
 
 ,T. andC 74 92 81 82 89 
 
 W's delinquents (By- 
 mental age) 60 66 80 85 92 
 
 K's unemployed (By men- 
 tal age) 23*28 73 81 90 
 
 * Note poor record of adults in this test. 
 
 IX Alternative 1. Naming the Months 
 
 8 9 10 11 12 13 14 
 
 T., L., O., etc 30 59 78 90 93 96 (2 of 3 checks correct) 
 
 T. andC 64 91 81 96 (No check given) 
 
 W's delinquents (Mental 
 
 age) 78 87 88 95 (2 of 3 checks) 
 
 ; K's unemployed (Mental 
 
 age) 88 94 100 100 
 
 IX Alternative 2. Stamps 
 
 7 8 9 10 11 12 
 
 T., L., O., etc 13 39 69 90 96 97 
 
 T. andC 58 60 73 85 90 100 
 
 T., T., andW 26 50 59 84 91100 
 
 XI Vocabulary, 30 DEFiNmoNs 
 
 8 9 10 11 12 13 
 
 T., L., O., etc 25 71 80 100 100 
 
 T. andC 14 35 60 72 77 90 
 
 T., T., andW 11 23 56 73 88 95 
 
 Hopwood 65 82 90 93 (Mass tests, written) 
 
 Houser 61 79 86 90 (Mass tests, written) 
 
 f W's delinquents 100 100 100 (By mental age) 
 
 K's unemployed 100 100 100 (By mental age) 
 
 Terman's hi^-school pupils, all passed 
 K's business men, all passed 
 
 ' X* Absurdities 
 
 8 9 10 11 12 13 
 
 T., L., O., etc 16 47 64 67 75 85 
 
 T. andC 30 40 52 55 73 88 
 
 T., T., andW 29 50 71 80 85 88 
 
 W's delinquents 68 79 100 84 (By mental age) 
 
 K|s unemployed 50 60 82 81 (By mental age) 
 
 High-school pupils, all passed 
 
 X' Drawinq Designs 
 
 8 9 10 11 12 13 14 
 
 T., L., O., etc 27 46 60 72 81 
 
 T., T., and W 36 50 61 72 90 
 
 W's delinquents 67 75 88 96 88 (By mental age) 
 
 K's unemployed 41 52 67 70 73 (By mental age)* 
 
 * Note inferiority of adults as compared with school children of same mental 
 ftge. 
 
172 STANFORD REVISION OF BINET-SIMON SCALE 
 
 X^ Reading fob 8 Memories 
 
 8 9 10 11 12 13 
 T., L., O., etc 26 55 69 80 93 
 
 T. and C 13 46 58 65 62 (Re-scored for 8 memori 
 
 T., T., andW 30 60 64 74 79 
 
 W's delinquents 62 75 88 (By mental age) 
 
 X' Comprehension, 4th Degree 
 
 9 10 11 12 13 14 
 
 T., L., O., etc 44 60 74 83 88 91 
 
 T. andC 37 59 70 80 86 
 
 T., T., andW 45 62 65 78 90 
 
 W's delinquents 62 70 86 97 100 (By mental age) 
 
 K's unemployed 70 85 98 100 100 (By mental age) 
 
 X* Naming 60 Words 
 
 8 9 10 11 12 13 14 
 
 T., L., O., etc 21 50 63 76 85 (60 in 3 minutes) 
 
 T. andC 35 57 67 83 82 (50 required in 2 m 
 
 utes) 
 
 T., T., andW 32 51 62 69 90 (50 in 2 minutes) 
 
 W's delinquents (Mental 
 
 age) 30 65 75 86 (60 in 3 minutes) 
 
 K's unemployed (Mental age) 40 60 56 60 (60 in 3 minutes*) 
 
 X Alternative 1. Six Digits 
 8 9 10 11 12 13 14 
 
 T., L., O., etc 32 66 71 80 87 
 
 W's delinquents 46 68 73 81 86 (By mental age) 
 
 K's unemployed 54 70 71 98 100 (By mental age) 
 
 X Alternative 2. 20-22 Stllables 
 
 8 9 10 11 12 13 14 15 16 
 
 T., L., O., etc 36 62 63 76 82 
 
 W's delinquents 46 58 55 82 86 95 (By men 
 
 age) 
 K's unemployed 40 63 74 85 100 92 (By mer 
 
 age) 
 
 X Alternative 3. Healt-Fernald Construction Puzzle 
 
 8 9 10 11 12 13 
 
 T., L., O., etc 31 46 67 81 90 
 
 W's delinquents 75 88 92 (By mental age) 
 
 K's unemployed 80 86 98 (By mental age) 
 
 * Note great inferiority of adult subjects, by mental age. These did i 
 seem to enter into the spirit of the test as children do. 
 
APPENDICES 
 
 173 
 
 XII' VOCABULAET, 40 DEFINITIONS 
 
 9 10 11 12 13 14 
 
 T., L.,0., etc 2 14 68 65 78 81 
 
 T. andC 6 15 44 57 62 
 
 T., T., andW 7 19 35 60 79 
 
 Hopwood 20 46 65 80 (Mass tests) 
 
 Houser 4 16 41 68 70 (Mass tests) 
 
 W's delinquents 10 36 62 78 (By mental age) 
 
 K's unemployed 20 65 66 93 100 (By mental age) 
 
 T's high-school pupils. All passed. 
 K's business men. All passed. 
 
 T's college students. All passed. (Mass tests of 65) 
 
 XII* Abstract Words 
 
 10 11 12 13 14 
 T., L.,0., etc 27 48 57 63 72 
 
 T. and C 20 38 51 65 67 (Binet's words. Re-scored since 
 
 1912) 
 
 W's delinquents 39 37 75 77 (By mental age) 
 
 K's unemployed 50 90 83 97 (By mental age) 
 
 T's high-school pupils (91 percent of all passed) 
 K's business men (90 percent of aU passed) 
 
 XII' Ball and Field (Superior Plan) 
 
 8 9 10 11 12 13 14 15 16 
 Combined Stanford 
 
 data for 908 cases 17 26 38 52 60 67 72 
 
 W's delinquents 64 65 81 78 86 84 81 (Mental age) 
 
 K's unemployed 61 58 60 66 74 90 85 (Mental age) 
 
 T's high-school pupils. . . (80 percent passed) 
 K's business men. (83 percent passed) 
 
 XIP Dissected Sentences 
 
 10 11 12 13 14 
 
 T., L.,0., etc 25 49 62 71 82 
 
 T. andC 24 32 62 66 83 
 
 T., T., and W 37 50 57 76 80 
 
 W's delinquents 21 56 66 77 (By mental age) 
 
 K's unemployed 27 64 63 (By mental age) 
 
 T's high-school pupils. (95 percent passed) 
 K's business men. (85 percent passed) 
 
 XII^ Interpretation of Fables, Score 4 
 10 11 12 13 14 15 16 
 
 T., L.,0., etc 37 63 62 70 81 
 
 T. and C 44 58 67 70 82 (Re-scored since 1912) 
 
 W's delinquents 30 63 64 68 83 100 (By mental age) 
 
 K's unemployed 20 28 62 60 73 94 (By mental age) 
 
 T's high-school pupils. (90 percent passed) 
 K's business men. (83 percent passed) 
 
174 STANFORD REVISION OF BINET-SIMON SCALE 
 
 XII« Five Digits Backwards 
 10 11 12 13 14 15 16 
 
 T., L., O., etc 40 61 66 71 73 
 
 Ws delinquents 30 45 56 68 80 95 (By mental age) 
 
 K's unemployed 33 48 55 60 67 78* (By mental age) 
 
 T's high-school pupils (75 percent passed) 
 K's business men. (79 percent passed) 
 
 * Note inferiority of older subjects as compared with children of same mental 
 age. 
 
 XII' PlCTtTHES, InTEKPRETATION 
 
 10 11 12 13 14 15 
 
 T.,L.,0.,etc 42 50 63 74 80 
 
 T., T., and W 30 47 65 78 84 
 
 W's deUnquents 35 46 54 62 71 (By mental age) 
 
 K's unemployed 50 67 71 87 82 (By mental age) 
 
 T's high-school pupils. (95 percent passed) 
 K's business men. (93 percent passed) 
 
 XII' Finding Similarities, Three Things 
 10 11 12 13 14 15 16 
 
 T., L., O., etc 43 67 64 73 78 
 
 W's deUnquents 44 60 84 91 96 (By mental age) 
 
 K's unemployed 50 52 56 63 73 75 (By mental age) 
 
 T's high-school pupils. (95 percent passed) 
 K's business men. (76 percent passed) 
 
 XIV Vocabulary, 50 Definitions 
 
 10 11 12 13 14 15 16 
 T., L., O., etc 20 45 66 
 
 T. andC 4 18 25 42 50 
 
 T., T., ajttdW 3 17 23 35 
 
 Hopwood 6 32 40 67 (Mass tests) 
 
 Houser 10 24 61 60 (Mass tests) 
 
 W's delinquents 5 10 40 58 70 90 (By mental age) 
 
 K's unemployed 10 35 46 73 80 90 100 (By mental age)* 
 
 T's high-school pupils. (AU passed) 
 
 K's business men. (AU passed) 
 
 T's college students. (All passed) 
 
 * Note superiority of adults as compared with children of the same mental age. 
 
 XI V^ Indtjction Test; Finding a Rule 
 
 11 12 13 14 15 16 
 T., L., 0., etc 17 38 47 56 
 
 W's delinquents 14 45 72 79 86 85 (By mental age) 
 
 K's unemployed 39 44 71 80 100 100 (By mental age) 
 
 T's high-school pupils. (78 percent passed) 
 
 K's business men. (90 percent passed) 
 
APPENDICES 175 
 
 XIV President and King 
 
 11 12 13 14 15 16 
 
 T., L., O., etc 10 22 39 52 
 
 T T. and W 18 34 44 55 
 
 W's delinquents ! 13 20 34 59 68 76 (By mental age) 
 
 K's unemployed 20 28 46 67 64 87 (By mental age) 
 
 T's high-school pupils. (88 percent passed) 
 K's business men. (80 percent passed) 
 
 XIV* Problems op Fact 
 11 12 13 14 15 16 
 
 T., L., 0., etc 31 39 49 56 
 
 T. andC 40 41 48 100 
 
 T., T., andW 38 60 61 70 
 
 W's delinquents 21 36 53 64 77 86 (By mental age) 
 
 K's unemployed 40 70 82 85 92 94 (By mental age) 
 
 T's high-school pupils. (90 per cent passed) 
 K's business men. (100 percent passed) 
 
 XIV Arithmetical Reasoning 
 11 12 13 14 15 16 
 
 T., L., 0., etc 26 38 43 50 
 
 T., T., andW 10 30 41 49 
 
 W's delinquents 22 34 45 62 86 (By mental age) 
 
 K's unemployed 10 28 48 73 82 87 (By mental age) 
 
 T's high-school pupils. (81 percent passed) 
 K's business men. (79 percent passed) 
 
 XIV« Reversing Hands op Clock 
 11 12 13 14 15 
 
 T., L., O., etc 30 54 64 78 
 
 T., T., and W 20 59 77 89 
 
 W's deUnquents 17 48 75 81 86 (By mental age) 
 
 K's unemployed 10 60 63 83 91 (By mental age) 
 
 T's high-school pupils. (90 percent passed) 
 K's business men. (86 percent passed) 
 
 XIV Alternate. Repeating Seven Digits 
 11 12 13 14 15 16 
 
 T., L., O., etc 36 41 62 59 (1 of 2 correct) 
 
 T and C .. 43 48 57 60 (Re-scored for 1 of 2 correct) 
 
 T., T., andW 37 46 56 65 
 
 W's delinquents 27 30 36 52 63 78 (By mental age) 
 
 K's unemployed "10 22 44 50 65 82 (By mental age) * 
 
 T's high-school pupils. (60 percent passed) 
 K's business men. (61 percent passed) 
 
 * Note inferiority of adults as compared with children of same mental age. 
 
176 STANFORD REVISION OF BINET-SIMON SCALE 
 
 Average Adult 1. Vocabttlabt, 65 DEPiisfiTioNS 
 12 13 14 15 16 
 
 T., L., O., etc 12 23 
 
 T. andC 4 9 22 
 
 T., T., andW 8 14 
 
 Hopwood 6 13 (Mass tests) 
 
 Houser 3 9 28 (Mass tests) 
 
 W's delinquents 4 32 62 (By mental age) 
 
 K'b unemployed 11 24 63 77 (By mental age) 
 
 T's high-school pupils. (84 percent passed) 
 K's business men. (75 percent passed) 
 
 T's college students. (96 percent passed) 
 
 Average Adttlt 2. Interpretation or Fable, Score 8 
 12 13 14 15 16 
 
 T., L., O., etc 12 23 31 
 
 T. andC 16 27 36 
 
 W's dehnquents 12 40 47 60 (By mental age) 
 
 K's unemployed 6 8 20 39 65 (By mental age) 
 
 T's high-school pupils. (66 percent passed) 
 K's business men. (60 percent passed) 
 
 Average Adult 3. Differences Between Abstract Words 
 
 11 12 13 14 15 16 
 T., L., O., etc 11 26 39 
 
 T. andC 16 24 29 44 
 
 W's delinquents 4 12 18 46 60 (By mental age) 
 
 K's unemployed 25 43 55 76 (By mental age) * 
 
 T's high-school pupils. (53 percent passed) 
 K's business men. (66 percent passed) 
 
 * Note inferiority of adults as compared with normal children of same mental 
 age. 
 
 Average Adult 4. Problem of Enclosed Boxes 
 
 12 13 14 15 16 
 T., L., O., etc 8 12 22 
 
 W's delinquents 24 30 38 52 70 (By mental age) 
 
 K's unemployed 10 13 40 38 70 (By mental age) 
 
 T's high-school pupils. (55 percent passed) 
 
 K's business men. (65 percent passed) 
 
 Average Adult 5. Repeating of Six Digits Backwards 
 
 12 13 14 15 16 17 
 
 T., L., O., etc 10 32 45 
 
 W's dehnquents 4 17 30 50 70 (By mental age) 
 
 K's unemployed 6 14 24 30 57 69 (By mental age) 
 
 T's high-school pupils. (56 percent passed) 
 K's business men. (60 percent passed) 
 
APJENDICES 177 
 
 AvEBAGE Adult 6. Learning a Code 
 12 13 14 15 16 17 
 
 T., L., O., etc 8 17 32 
 
 T., T., andW 10 19 26 
 
 W's delinquents 10 20 60 62 70 (By mental age) 
 
 K's imemployed 19 73 (By mental age) 
 
 T's high-school pupils. (60 percent passed) 
 K's business men. (42 percent passed) 
 
 Average Adult. Alternative 1. 28 Syllables 
 
 11 12 13 14 15 16 
 
 T., L., O., etc 10 26 35 39 
 
 T.andC 21 33 42 50 
 
 T., T., andW 15 37 40 48 
 
 W's delinquents 8 14 24 35 46 58 (By mental age) 
 
 K's unemployed 12 20 31 42 57 (By mental age) 
 
 T'b high-school pupils. (44 percent passed) 
 
 K's business men. (69 percent passed) 
 
 AvEKAGB Adult 2. Compeehension op Physical Relations 
 
 12 13 14 15 16 
 T., L., O., etc 5 19 33 
 
 W's delinquents 31 38 46 53 60 (By mental age) 
 
 K's unemployed 10 22 69 46 74 (By mental age) * 
 
 T's high-school pupils. (65 percent passed) 
 
 K's business men. (80 percent passed) 
 
 * Note superiority of older subjects as compared with children of same mental 
 age. 
 
 StrpERioB Adult 1. Vocabulakt, 75 Definitions 
 15 16 17 18 
 
 W's delinquents 5 10 40 (By mental age) 
 
 K's unemployed 5 38 60 (By mental age) 
 
 T's high-school pupils. (61 percent passed) 
 K's business men. (50 percent passed) 
 
 T's college students. (85 percent passed) 
 
 Superior Adult 2. Binet's Paper-Cutting Test 
 12 13 14 16 16 17 18 
 
 T.,L., 2 13 26 
 
 K's unemployed 11 27 38 64 61 (By mental age) 
 
 T's high-school pupils. (30 percent passed) 
 
 K's business men. (43 percent passed) 
 
 Superior Adult 3. Repeating Eight Digits 
 12 13 14 16 16 17 18 
 
 K's unemployed 6 9 11 27 34 63 62 (By mental age) 
 
 T's high-school pupils. (37 percent passed) 
 K's business men. (44 percent passed) 
 
178 STANFOKD REVISION OF BINET-SIMON SCALE 
 
 Sttperior Adtjlt 4. Sense op Relation 
 
 12 13 14 15 16 17 
 T., L., O., etc 13 27 30 
 
 W's delinquents 16 20 24 (By mental age) 
 
 K's unemployed 9 18 25 38 50 (By mental age) 
 
 T's high-school pupils. (65 percent passed) 
 
 K's business men. (26 percent passed) 
 
 SuPERiOB Adttlt 5. Seven Digits Backwards 
 
 T's high-school pupils. (40 percent passed) 
 
 T's 14-yr.-old3 in 8th grade. (13 percent passed) 
 
 Superior Aditlt 6. Ingenuity Test 
 
 13 14 15 16 17 18 
 T., L., O., etc 6 11 
 
 W's delinquents 8 6 30 43 (By mental age) 
 
 K's unemployed 14 16 29 47 57 (By mental age) 
 
 T's high-school pupils. (25 percent passed) 
 
 K's business men. (36 percent passed) 
 
APPENDICES 179 
 
 APPENDIX II 
 
 Form Used for Gathering Sitpplementary Inpohmation 
 To the Teacher 
 
 The information rendered on this blank will be held strictly confi- 
 dential, will be used for statistical purposes only, and without the men- 
 tion of any child's name. The information will aid greatly in connec- 
 tion with a revision of the Binet mental tests. 
 
 Even it the child's social status is not accurately known, please 
 underscore the word which you think would properly represent it, and 
 if the uncertainty is very great, add a question mark. 
 
 "Additional information," as called for in the last item, will be 
 especially welcome. 
 
 1. Name of pupil Age 
 
 2. Name of school 
 
 3. Present grade (Grade attended March, 1914, was ) 
 
 4. Quahty of child's school work (underscore appropriate word) : 
 
 Very inferior, inferior, average, superior, very superior. 
 
 5. Teacher's estimate of child's intelligence as compared with average 
 
 children of the same age (underscore) : 
 
 Very inferior, inferior, average, superior, very superior. 
 
 6. Social class to which the child belongs (this refers to the intellectual 
 
 level, the culture and the general level of the home environment) : 
 Very inferior, inferior, average, superior, very superior. 
 
 7. Additional information which will throw light on the child's in- 
 
 teUigence, school success or social status. 
 

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