Tit 3t^aca, Hem ^ark BOUGHT WITH THE INCOME OF THE SAGE ENDOWMENT FUND THE GIFT'OF HENRY W. SAGE 1891 3 c n Cornell University Library LB3244 .T49 Ventilation in reiation to mentai worl<, olin 3 1924 032 714 523 VENTILATION IN RELATION TO MENTAL WORK BY E. L. THORNDIKE, W. A. McCALL AND J. C. CHAPMAN TEACHERS COLLEGE. COLUMBIA UNIVERSITY CONTRIBUTIONS TO EDUCATION, No. 78 PTTBUSHED BT ^sutlferB (S-oUssf. Columbia Sniv^rBttH NEW YORK CITY 1916 Copyright, 1916, by Teachers College, Columbia University Pkebs of Steinman & FOLTZ, Lancasteb, Pa. CONTENTS iNTEODXrCnON 1 E. L. Thorndike Exp ebtmf.nt I. Effect of Conditions of the Air on Mental WoRK, THE Condition being changed daily 3 J. C. Chapman Experiment II. Effect of Conditions of the Air upon the Rate of Improvement of Mental Functions 24 E. L. Thorndike and W. A. McCall Experiment III. Effect of Conditions of the Air trpoN the Accuracy of Judgment 46 W. A. McCall and E. L. Thorndike Effect of Certain Conditions of the Air upon the Choice of Alternatives to Mental Worx 60 W. A. McCall and E. L. Thornddce Summary and Interpretation 75 E. L. Thorndike Appendix 81 Cornell University Library The original of tiiis book is in tine Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924032714523 VENTILATION IN RELATION TO MENTAL WORK INTRODUCTION By EDWARD L. THORNDIKE The experiments reported in this monograph were all carried on under the auspices of the New York State Commission on Ventilation* with the aid of a fund given by Mrs. Elizabeth Milbank Anderson. The authors are indebted to the members of the Commission for criticisms of the work while it was being planned and during its coiu'se and to many of the investigating staff for co-operation. The experi- ments reported here were parts of an organized plan for the most economical use of the Commission's laboratory, physiological, psy- chological and medical data often being obtained during the same day. Within the limitations thereby set, the effort was made to find out important facts to serve as a basis for the policy of ventilating schools, shops, oflSces, and the like so far as concerns the mental welfare of their workers. The chief aims were to measure the effect of heat and expired air upon the quantity and quahty of the mental products produced per unit of time, and upon the readiness of individuals to work. Certain statements made by them as to their felt fitness for work and general well-being will also be reported here. The practice of ventilation seeks to secure not only mental ef- ficiency, and comfort as a means to efficiency, but also comfort for its own sake, including the gratification of certain specially refined tastes. The experiments reported here are little concerned with the personal enjoyment of the subjects save in so far as indirectly it influenced the products which they produced. Further, the efiects of dryness and wetness and of cold are left unmeasured by the present experiments, though it is hoped that a report concerning the' former can be made later. We have measured the effect of certain mental activities chosen to represent fairly the mental work of schools and offices, and at *C. E. A. Winslow, Chairman, D. D. Kimball, Frederick S. Lee, James Alexander Miller, M. D., Earle B. Phelps, Edward Lee Thorndike; George T. Palmer, Chief of Investigating Staff, Joseph Herzstein, Secretary. 2 Ventilation in Relation to Mental Work the same time to be measurable with reasonable accuracy and con- venience. As a consequence of the second requirement, forms of work demanding an extremely complex organization of mental material, such as writing a sermon or planning a business campaign, and forms of work involving social restraints, personal impressiveness and conflict, such as teaching a class, selling goods to a customer, or keeping one's temper in annoying human encoimters, are not repre- sented. The tests used are all of work with ideas, symbols and mechanisms, not of work with persons. EXPERIMENT I THE EFFECT OF CONDITIONS OF THE AIR ON MENTAL WORK, THE CONDITION BEING CHANGED DAILY By J. C. CHAPMAN General Conditions The object of this research was to investigate the effect of certain atmospheric conditions upon mental efficiency. For this purpose the subjects employed were tested in various functions under vary- ing external conditions of temperature and humidity and air circu- lation. The experiment was so arranged as to eliminate practice and individual differences; the method of the experiments will be described in detaU later. The dates of the experiments were as shown in Table 1. Physical Conditions The experiments were performed at the Laboratory of the New York State Commission on Ventilation, where the complete ventila- tion plant had been fitted. A fuU description of the mechanical part of the plant is presented elsewhere;* it will be sufficient to give here a general account of the arrangement. The plant consisted of two rooms: 1. Observation room (thermally insulated). 2. Control room. In the control room was the mechanical part of the plant,, which was capable of supplying, at desired rates, air of required tempera- ture and humidity to the observation room. There was also a re- frigerating plant capable of cooling the room in very short periods. In addition, fans were employed in the observation room itself for rapid circulation of the air. By means of this plant it was possible *D. D. Kimball and G. T. Palmer: The Experimental Laboratory of the New York State Commission on Ventilation: Transactions of the American Society of Heating and Ventilating Engineers, 1915, Vol. 21, pp. 135-207. 3 4 Ventilation in Relation to Mental Work to maintain a comparatively steady physical condition of the atmos- phere for any length of time. TABLE 1 Program of Work; Experiment I 10-14 1 17-21 \ 8-12 j 1913, Nov. 1&-14 Nov. 17-21 [• Preliminary tests. " Dec. ' " Dec. 15-19 1914, Jan. 26-30 " Feb. 2-6 y First five weeks of Experiment I. " Feb. 9-13 " Feb. 16-20 " Feb. 23-27 " Mar. 2-6 " Mar. 9-13 } Second five weeks of Experiment I. " Mar. 17-20*1 " Mar. 23-27 The conditions to be contrasted in Experiment I were as shown in Table 2. It should be noted, however, that, as shown later in Table 3, the CO2 percentages did not rise much, even when the same air was recirculated throughout the day. The recirculation was found necessary by those operating the plant in order to maintain the other conditions required. Condition C differs from condition A therefore, not by a markedly less CO2 content, but only by what- ever differences existed between outside and recirculated air under the conditions of the plant's operation. TABLE 2 Desired Physical Conditions of the Observation Room During Experiment I Movement Air Supply Relative Humidity Temperature A. No fans No outside air 80% 86 F (30C) supplied B. 4 fans at No outside air " " high speed supplied C. No fans 45 cu. ft. per rain. " " per person of outside air D. No fans No outside air 50% 68 F (20C) supplied E. No fans 45 cu. ft. per min. " " per person of outside air * One day omitted. The Efect of Conditions of the Air on Mental Work Table 3 gives a detailed account of the conditions actually real- ized day by day. TABLE 3 Recorded Room-Conditions During Experiment I R = recirculated air. F = outside air introduced. Beg., Mid., and End refer to the beginning, middle, and end of the four-hour period from 2 to 6 p. m. I 2 3 4 5 6 7 Cu. ft. per min. Air per Humid- Temper- Subjects Date Supply person ity ature Beg. Squad I 12/15 R 50 80 86 12/16 R 50 77 87.5 12/17 F 48 76 87.5 12/18 36 74 12/19 F 48 48 68 Squad II 1/26 cir. 35 cir. 70 1/27 F 56 58 66.5 1/28 R 38 65 89 1/29 R 55 74 88 1/30 F 55 68 86.5 Squad III 2/2 F 44 76 86.5 2/3 R 44 48 72.5 2/4 F 45 42 67.5 2>5 R 48 70 86.5 2/6 R 48 72 86.5 Squad IV 2/9 R 45 68 88.5 2/10 F 20 78 85 2/11 R 48 48 69 2/12 F 44 44 67 2/13 R 48 80 85.5 Squad V 2/16 F 45 52 68 2/17 R 50 76 86.5 2/18 R 40 74 87 2/19 F 45 72 85.5 2/20 R 20 35 74 Squad VI 2/23 R 45 75 87 2/24 R 43 74 86.5 2/25 F 40 73 87 2/26 R 40 52 67.5 2/27 F 45 47 68.5 Squad VII 3/2 R 40 54 67 5/S F 45 48 68 3/4 R 40 70 88.5 3/5 47 88.5 3/6 F 45 78 86 8 9 COz parts per 10,000 Mid. End Normal classroom 5.5 7.5 8.0 6.0 9.0 8.0 12.0 7.0 5.0 7.0 16.0 26.0 12.0 Ventilation in Relation to Mental Work TABLE 3—1 Continued I 2 3 4 Cu. ft. per min. 5 6 7 8 COz 9 parts Air per Humid- ■ Temper- per 10,000 Subjects Date Supply person ity ature Beg. Mid. End Squad VIII 3/9 F 45 77 86.5 4.5 3/10 R 40 53 68 7.5 3/11 F 45 51 68.5 6.5 6.0 3/12 R 40 74 87.5 3/13 R 30 68 88 4.5 9.0 Squad IX 3/16 Omitted 3/17 R 40 50 86 3/18 R 40 76 85.5 6.5 3/19 R 40 43 70 3/20 F 45 54 67.5 6.0 6.5 Squad X 3/23 F 45 54 67.5 3/24 R 35 45 69 3/2S R 43 75 84.5 4.5 8.5 3/26 F 45 84 84.5 3/27 R 40 81 85.5 6.0 The subjects were men students of the College of the City of New York. No selection of the subjects was made on the basis of ability — the subjects themselves volunteered for the work and were paid upon a commercial basis. The only test which each subject had to undergo before receiving employment was to name colors and per- form mental multiplication of three-place by three-place numbers. It may be said that out of approximately sixty subjects, these tests only eliminated three individuals. Owing to the size of the observation room and the difficulty of controlling its conditions, it was not feasible to test more than four subjects at any one time. The final arrangement was to have for each complete experiment five squads of four subjects, each squad to occupy the room for four hours a day on five days of each week. The experiment thus extended over a period of five weeks. Each squad of fovir subjects formed a distinct unit, and when its own par- ticular week had elapsed, the results which it gave were complete. There were five days diuring which each squad occupied the room. On each of these days a different physical condition was maintained throughout the four-hour test period. Throughout the five weeks of each half of the experiment the distribution of these various con- ditions was so arranged that the favorable and unfavorable condi- tions came in all possible orders during the week period. Thus at the end of the five weeks any particular condition had occurred on The Effect of Conditions of the Air on Mental Work 7 the first day in one week, the second day in another week, the third day in another week, the fourth day in another and the fifth day in another week. Such an arrangement was necessary in order to eUminate the factor of practice. The Tests Color-naming. The subject was provided with a Woodworth- Wells blank on which were printed in random order one hundred small squares of varying primary colors; nothing of the nature of discrim- ination of shades was necessary. The subject was made to name each of the one hundred squares in as rapid succession as possible. The time taken to name the complete series was measiured by the experimenter. In the case of any misnaming of the color the subject was stopped and made to return to the point at which the mistake arose, in this way adding to the time taken for the test. The scores recorded are the times taken to name correctly the 100 colors. Cancellation of 2's. The subject was provided with a Woodworth- Wells cancellation sheet, in which there are a series of random group- ings of five figures. In this sheet a certain specified number, 2 in the first instance, had to be cancelled. The object of the experiment was to omit as few cases of the specified number as possible and to complete a maximum amount of cancellation in the period allowed — 60 seconds. The numerical results as given in the tables are calcu- lated on the following arbitrary basis: 2 (numbers cancelled correctly) — 2 (numbers wrongly omitted) — 3 (nimibers wrongly marked). From this method of scoring it will be noticed that additional speed may reduce one's score if gained at the expense of accuracy. On the other hand, additional speed may outweigh complete accuracy. This was pointed out to the subjects at the commencement of the work, the scores from day to day revealing to what extent speed was being gained at the expense of accuracy. Cancellation of 3's. The above test was repeated, cancelling 3's instead of 2's. In all- other particulars the two tests were similar. Hard Opposiies. The subject was provided with a list of fifty words as used by Hollingworth, of which the opposites in each case had to be named; a certain range of choice of opposites was allowed. The ob- ject of the experiment was to complete . this list in a mimimum time. In the case of the misnaming of any opposite, the subject 8 Ventilation in Relation to Mental Work was stopped and made to return to the point at which the mistake arose: at any time when more than 15 seconds was taken to name any particular opposite, the subject was told the correct word. The time taken to complete the list with the necessary corrections and promptings was measured. After the first test or so, it rarely hap- pened that any prompting was necessary, though throughout, owing to the high speed, occasional mistakes arose. A different arrange- ment of the words was used in each of these tests. The score as given in the tables is the time taken to name the fifty opposites correctly, imder the above conditions. Addition. The subject was provided with two sheets of the set of blanks containing columns of ten one-place numbers as devised by Thorndike. Different sheets were used from day to day to pre- vent possible memorizing on the part of the subjects. The object of the test was to complete the maximxmi number of correct additions in the time allotted — 10 minutes. The answers were written at the base of the colximns. If an answer was wrong no credit was given for that column. The residts stated in the tables are the number of columns added correctly in 10 minutes. Mental Multiplication. The subject was provided with a sheet containing a random selection of pairs of three-place numbers ar- ranged by putting any three-place number containing no digit lower than three and repeating no digit, with another such number. These pairs had to be multiplied mentally, nothing being written down until the final product was obtained. The subjects were permitted to look at the problem continuously. The period allowed for the tests was 20 minutes. The method of scoring was as follows: Each example done correctly was credited 10, minus 1, 2, 3, 5, for one, two, three, and four figures wrong respectively. Zero credit was given in an example with less than two figures correct. The score recorded in the tables is the product produced in 20 minutes after deduction for errors on the above scale. The tests were performed each week on the squad of four subjects, on the days from Monday to Friday inclusive. The Saturday pre- vious was devoted to a preliminary trial, in which each squad was put through the series of tests. The rules were explained, while added uniformity was obtained by putting in writing before each subject the object of the test, and the method of scoring. Any ques- tions which arose on the trial day were answered, so that on the days of the test no misunderstanding could arise. By devoting a The Effect of Conditions of the Air on Mental Work 9 little time on this preliminary day a considerable amoimt of irregu- larity was avoided in the initial measmrements. Each afternoon of the week was divided into two sections, the periods falling between 2:30 and 3:45 and 4:15 and 5:30 p. m., re- spectively. In this manner there were ten periods devoted to the experiment during the five days. During each of these ten periods the whole series of mental tests was employed. The distribution of time meant that the tests were separated by 1^ and 23 hours. A program of the work of each day is shown below. 2 :00-2 :30 p. m. physiological tests 2:30-3:45 p. m. psychological tests 3:45-4:15 p. in. physiological tests 4:15-5:30 p. m. psychological tests 5:30-5:00 p. m. physiological tests The results of the physiological tests will be pubhshed elsewhere. A full record of the scores made by each individual will be found in Tables 6 to 12. In addition to the tests at the end of each after- noon the subject was made to report on his physical condition. The scale of the report was as foUows: 5. I feel as comfortable as I ever do, or nearly so. 3. I feel about as I usually do at the close of an afternoon of hard mental work. 1. I feel as uncomfortable as I would with a severe headache or an attack of the grippe. 4. My condition is about halfway between 3 and 5. 2. My condition is about halfway between 1 and 3. Soon after these experiments started, it became apparent that there was an tmcertainty about the meaning of this scale. On the hot and humid days, it repeatedly happened that a subject would ask if he should report on his condition just at the moment or upon what he knew his condition would be after returning to the fresh air outside the room. The decision was made that the report should be based upon the more or less permanent condition rather than upon the temporary condition, such as would be produced at the time by the depressing effects of a high temperature combined with high humidity. This arbitrary decision should be noted, if correct interpretation is to be given to the report of the condition of the subject. Had this report been based upon present feelings, there would have been a much more noticeable difference in the reports on the days where the good and bad conditions were produced. If, instead of physical condition, the satisfyingness of the work had been 10 Ventilation in Relation to Mental Work measured on a suitable scale, the difference between the reports on the hot and normal days would, in the opinion of the writer, have been large. Method of treating the numerical results of the five-week period. At the end of the five weeks, each of the five conditions of ventilation has occurred five times, once in each week on varying days from the first to the last day. If the scores made on the five days when any particular condition was produced are added and averaged, an estimate is obtained of the efficiency of all of the twenty individuals under this particular condition. Similarly for the other four condi- tions, by summation and taking averages we obtain measures of the efficiency under each of the conditions. Owing to this arrangement of the days it will be observed that the influence of practice is largely equalized. In Table 4, the scores obtained under each of the five conditions by the twenty individuals have been averaged. TABLE 4 Average Scores in Each Test under Each Condition of Ventilation; Experiment I : First Five Weeks Condition of Room E* D B C A Fans No F. 68° F. 50% No R. 68° F. 50% High speed R. 86° F. 80% No F. 86° F. 80% No R. 86° F. 80% P.E.'s Supply of air Temperature Humidity of Column E. Color 49.2 52.6 101.5 74.4 56.6 3.6 48.5 52.6 103.1 76.5 60.5 3.9 48.2 54.0 100.7 75.6 62.8 3.2 48.5 57.1 100.7 74.8 59.7 3.0 48.9 55.4 102.1 76.0 57.2 2.5 54 (time) Odd 1 3 (time) 1.0 (time) Addition 2 8 Mental Multiplication.. . . Report on sub- ject's condition by himself 2.4 .07 * The P.E. of the average scores of this column is shown in the last column. For each test the P.E. remains of the same order. First Five- Week Period These results show that, within the limits of experimental error, efficiency when tested by the quantity and quality of the product produced per unit of time is independent of the external conditions The Effect of Conditions of the Air on Mental Work 11 of ventilation which were artificially produced in this experiment. Though the subject suffered considerable inconvenience and dis- comfort from the atmospheric conditions on three days of the week, yet the scores on these days were as high as on the other days. In other words, the difference between the conditions is that of comfort and satisfyingness and not that of quantity and quality of product produced. Of the three days when the temperature and humidity were high the day when the fans were directed on the subjects was the least unpleasant — the relief from the rapid circulation of the air caused by them was great, keeping the upper part of the body, including the face, reasonably cool. On the other two days, the subjects were in a continuous state of perspiration; the air was hot and heavy, having a tendency to produce sleepiness and depression. During the first five weeks of Experiment I, the subjects were provided with light xmder-shirts and sweaters. On the warm days they were allowed to remove the sweaters, leaving only the light undershirt. This approximates to the conditions in ordinary life, for individuals working for any length of time in hot rooms will eventually dress accordingly. Even when the Ughtest clothes were worn on the two days when it was 86° and no fans were used, it was impossible to keep cool, and judged by the usual standards of mere physical well-being, the general comfort was greatly reduced. Experiment I, Second Five Weeks Experiment I was repeated, the only differences in procedure being: 1. The substitution of typewriting for color-naming and cancella- tion tests. 2. The subjects were made to wear the sweaters on the hot days as well as on the cool days. Rules for Typewriting Test. The subjects were given sufficient preliminary practice with the machines to enable them to understand their working. On the days of the test during each of the ten periods, ten minutes was devoted to typewriting. Short pieces of uniform simple prose were used as the matter for writing, different extracts being employed at each of the ten tests. The method of scoring was as foUows: One unit was given for each correct Hne of the test, the lines being reckoned from the extracts which were so chosen as to give lines of equal length; one-tenth of a unit was subtracted for n Ventilation in Relation to Mental Work each word in which an error was made. Mistakes in spacing and serious mistakes in punctuation were also counted as errors which deducted .1 from the score. Owing to one of the weeks being broken, only four conditions were produced the necessary five times to eliminate the practice effect. In Table 5 the results' are presented in the form previously used. TABLE 5 Average Scores in Each Test under Each Condition of Ventilation: Experiment I, Second Five Weeks Condition of Room Fans Supply of air Temperature Humidity Test Opposites (time) Addition Mental Mult Mental Mult.t Typewriting Report on subject's condi- tion by subject himself E* B No out- side air 68° F. 50% No R. 68° F. 50% High speed R. 86° F. 80% No R. 86° F. 80% P.E. of Col. E. 58.5 68.8 52.6 50.2 88.2 3.8 62.5 65.3 45.9 46.6 84.4 3.8 54.2 69.1 58.8 47.5 89.4 3.2 57.4 70.0 56.4 50.8 86.2 3.0 1.7 2.2 2.4 3.6 0.9 * The P.E.'s of the values of this column are shown in the last column. For each test the P.E. remains of same order. t Results of two individuals are omitted whose improvements were ab- normal so that the factor of individual differences is not eliminated. The result of the second five weeks, in which the subjects were made to wear sweaters on the hot days as well as on the normal days, confirms the previous result. When the probable errors of the averages are considered, it appears that there is no diminution in the scores imder the abnormal conditions of temperature and humidity (86° F and 80% rel. hum.). If the numerical data are interpreted strictly, it would seem that there is actually a slight increase under the bad condition. Explanation of Tables 6 to 12 Tables 6 to 12 give the detailed scores for both the first and second five-week experiments. Squads I-V inclusive represent the first experiment, while Squads VI-X inclusive represent the second The Effect of Conditions of the Air on Mental Work 13 experiment. In the second experiment one of the weeks was broken. In every case the letters E and L refer to early and late periods of the day's session. The dates in these tables correspond to the dates in Table 3. All scores reported here are net scores, a fair allowance having been made for errors. The following key, which is for all the tables from 4 to 10, gives the order of the conditions for each squad. The figure 1 under any condition means that that condition came on the first day of that squad's practice, and so on. E 2422 Fans No out- Supply of air side air Temperature 68° F. Humidity 50% 5 2 3 4 1 5 2 3 4 1 Squad I Da Squad II " Squad III " Squad IV ' Squad V ' Squad VI " Squad VII " Squad VIII " Squad IX " Squad X " D 1122 No R. 68° F. 50% 4 1 2 3 5 4 1 2 3 2 B 4133 High speed R. 86° F. 80% 2 4 5 1 3 2 4 5 1 3 C 2433 No out- side air 86° F. 80% 3 5 1 2 4 3 5 1 A 1133 No R. 86° F. 80% 1 3 4 5 2 1 3 4 2 5 TABLE 6 Color Naming: Time in Seconds Taken on Each Successive Day by Nine- teen Individuals Each early and late period has two divisions. The dpper row always repre- sents the first division Squad I E L I2ll6 E L I2/I7 E L 12/18 E L 12/19 E L Grossberg 58 56 S3 50 50 48 46 46 43 47 58 54 53 SO 44 54 49 49 52 49 Hanson .. SO 46 50 47 45 44 45 42 44 45 44 42 42 44 44 44 45 47 46 44 Schachter .. 63 70 60 64 52 59 57 57 54 61 54 56 55 62 57 62 54 60 58 62 Fried .. 44 44 43 44 41 47 44 43 41 43 40 37 40 38 39 40 41 40 38 41 14 Ventilation in Relation to Mental Work TABLE 6— Continued Squad II 1/26 1/27 1/28 1/2Q EL EL EL EL Schroeder 57 54 S3 51 48 51 46 52 54 52 49 52 47 51 SO 54 Frey 45 44 42 42 40 44 41 41 47 49 40 44 48 44 41 46 Conlan 76 67 63 63 57 59 50 56 67 67 62 60 56 56 56 58 Sguad III 2/2 2/3 2/4 2/5 EL EL EL EL Mantinband. . . . 41 42 43 44 34 41 48 41 42 43 40 51 44 46 40 39 Fisch 57 54 56 57 57 58 53 54 59 53 65 57 64 61 60 61 Tanz 50 47 52 48 43 48 47 44 51 47 48 50 44 51 47 46 Smith 61 58 55 51 59 54 53 48 61 61 55 58 51 61 54 58 Sguad IV 2/p 2/10 2/ 11 2/12 EL EL EL EL O'Connell 66 58 59 59 59 56 57 55 67 59 65 57 56 62 57 61 Kraus 53 48 45 50 40 46 50 50 46 45 44 48 49 47 42 47 Godnick 53 47 45 48 42 41 49 47 41 48 47 46 40 46 46 46 Ennis 45 41 38 38 37 36 34 39 41 42 41 39 38 39 37 39 Squad V 2/16 2/17 2/18 2/19 EL EL EL EL Strumpf 47 47 54 49 42 49 47 48 50 52 53 49 51 47 49 54 Schatz 45 45 42 41 42 39 41 42 45 48 43 45 41 43 38 38 Deutsch 45 41 40 44 39 42 36 40 44 42 39 41 39 42 38 41 Margolin 54 49 50 55 48 47 52 50 51 55 47 50 46 48 50 48 I/. 30 E L 47 49 51 50 42 49 46 SO 55 51 53 S3 2/6 42 40 37 38 SO 55 54 69 41 42 41 39 56 55 49 55 2/13 E L 51 S3 52 54 42 43 48 51 44 44 45 44 38 37 40 39 2/20 E L 46 44 46 45 42 39 39 43 43 38 39 39 46 49 48 49 The Effect of Conditions of the Air on Mental Work 15 TABLE 7 Cancellation of z's and 3's: Product Produced on Each Successive Day BY Nineteen Individuals In every case the upper row is for 2's and the lower row for 3's Squad I 12/1S 12/16 12/17 12/18 12/19 EL EL EL EL EL Grossberg 98 104 97 94 122 144 116 114 120 114 102 101 102 114 110 116 109 116 110 112 Hanson 102 88 103 112 122 104 122 120 114 118 96 103 111 102 112 108 106 122 112 107 Schachter 76 82 100 90 114 104 112 101 116 116 82 92 98 94 110 110 114 112 114 110 Fried 94 94 108 108 108 107 110 113 116 118 98 97 110 106 112 114 116 107 122 116 Squad II 1/26 1/27 1/28 l/2p 1/30 EL EL EL EL EL Schroeder 90 100 98 96 96 98 95 90 102 90 76 79 96 95 97 92 98 91 98 95 Frey 67 57 78 78 74 78 82 82 75 84 76 72 76 72 82 75 80 82 82 82 Conlan 76 72 78 78 82 90 83 90 84 94 72 82 82 82 92 88 88 84 84 84 Squad III 2/2 2/3 2/4 ■ 2/s 2/6 EL EL EL EL EL Mantenband. . . . 62 80 74 100 100 98 110 114 102 106 78 78 82 96 98 102 102 104 104 110 Fisch 84 78 82 90 88 90 92 90 98 90 90 92 92 98 96 106 98 108 98 110 Tanz 78 78 80 84 80 92 110 96 100 110 80 72 88 90 94 98 98 100 96 102 Smith 94 96 100 94 116 116 108 116 102 114 100 102 100 102 110 106 110 102 108 120 Squad IV 2/9 2/10 2/ 11 2/12 2/13 EL EL EL EL EL O'Connell 75 74 70 74 -82 72 74 82 84 80 68 78 86 76 76 76 78 76 76 78 Kraus 98 96 102 90 108 110 119 112 112 118 102 88 102 106 112 110 116 112 118 118 Godnick 96 104 102 124 124 140 128 112 120 116 106 100 106 98 110 124 122 128 112 126 Ennis 84 82 100 86 98 98 102 96 106 116 88 96 96 108 100 98 104 110 114 118 16 Ventilation in Relation to Mental Work TABLE 7 — Continued Squad V z/id 2/17 2/18 2/19 2/20 EL EL EL EL EL Strumpf 110 90 118 116 118 114 118 118 122 118 104 98 114 100 114 110 107 108 124 116 Schatz 116 104 116 116 122 122 122 130 170 130 112 100 116 116 122 124 126 130 134 120 Deutsch 82 90 96 122 104 106 114 114 120 118 96 92 114 114 114 114 114 126 128 124 Margolin 92 104 116 108 118 116 128 128 132 138 106 108 118 120 110 116 128 123 136 142 TABLE 8 Naming Opposites: Time in Seconds Taken on Each Successive Day by Thirty-nine Individuals Each early and late period has two divisions. The upper row always repre- sents the first division Squad I 12/1S 12/16 12 1 17 12/18 12/19 EL EL EL EL EL Grossberg. . . . . . . 101 94 57 67 S3 48 48 44 39 37 66 62 59 49 47 39 37 32 38 34 Hanson 105 125 78 79 65 55 54 55 47 48 104 i28 83 68 54 53 54 43 45 49 Schachter 116 76 51 59 51 52 46 42 51 49 99 67 46 52 45 43 37 44 47 38 Fried 94 48 43 46 42 40 34 32 36 36 53 45 44 44 33 31 28 31 31 27 Squad II 12/26 12/27 12/28 12/29 12/30 EL EL EL EL EL Schroeder 89 72 69 60 59 55 54 61 55 55 81 64 62 56 58 51 49 53 63 48 Frey 121 79 75 68 71 61 58 65 59 58 76 81 65 69 66 57 59 52 54 54 Conlan 114 90 64 67 60 56 51 49 50 44 92 94 55 55 48 48 47 51 42 43 Squad III 2/2 2/3 2/4 2/5 2/6 EL EL EL EL EL Mantenband. . . . 78 60 49 47 37 42 36 46 42 37 53 51 61 43 43 39 38 32 36 32 Fisch 61 56 SO 42 40 63 41 38 37 35 43 47 43 39 39 40 38 41 34 39 Tanz 105 80 60 56 52 55 S3 56 48 47 104 68 67 52 46 53 53 46 48 39 Smith 195 118 110 90 56 77 47 52 48 49 The Effect of Conditions of the Air on Mental Work 17 TABLE 8 — Continued Squad IV 2/9 E L 2/10 E L 2/II E L 2/12 E L 2/13 E L O'Connell .. 104 99 80 76 67 81 66 69 66 60 64 59 58 55 60 56 46 50 54 51 Kraus .. 109 83 65 89 48 42 55 49 51 41 42 43 44 50 41 36 46 40 40 38 Godnick .. 87 52 63 51 43 39 39 37 41 39 41 33 35 28 32 28 33 30 25 27 Ennjs .. 77 57 59 58 51 40 46 39 46 38 38 38 36 36 41 36 36 34 31 32 Squad V 2/l6 E L 2/17 E L 2/18 E L 2/10 E L 2/20 E L Strumpf .. 65 48 54 55 50 45 47 42 40 39 37 40 44 34 39 38 39 38 35 33 Schatz .. 73 55 63 54 75 52 56 49 50 45 49 42 41 33 43 35 37 37 37 34 Deutsch .. 123 90 61 56 50 45 45 39 40 36 40 36 37 33 38 32 34 34 35 31 Margolin .. 79 51 65 55 59 50 55 54 53 47 53 46 49 41 45 41 44 43 46 39 Squad VI 2/23 E L 2/24 E L 2/25 E L 2/26 E L 2/27 E L Robinson. . . . ... 114 111 79 67 65 63 70 67 78 49 60 61 55 61 61 50 53 53 45 51 Mendel ... 77 74 59 50 60 46 48 53 44 43 40 37 39 33 38 39 41 36 38 38 Klein . .. 143 101 98 77 68 88 68 57 66 62 55 53 50 54 61 53 55 48 45 48 Doun , .. 124 78 93 63 76 72 68 65 70 55 56 52 58 42 51 44 49 47 37 38 Squad VII 3/- E 2 L 3/3 E L 3/4 E L 3/S E L 3/6 E L Regard ... 127 68 75 67 51 43 61 43 41 35 49 37 39 34 40 40 38 41 34 34 Nemser . .. 152 124 94 83 94 78 98 77 75 66 71 68 80 94 75 60 74 66 77 61 Smith . .. 90 58 50 45 47 52 57 38 38 40 39 34 33 30 32 30 32 32 29 29 WalUs . .. 77 75 54 44 43 41 40 39 42 35 38 39 39 32 35 35 32 35 29 33 18 Ventilation in Relation to Mental Work TABLE Z— Concluded Squad VIII 3/9 3/io s/n 3/i2 3/i3 EL EL EL EL EL Kummerl 96 102 62 74 75 65 50 60 53 50 106 73 67 69 58 61 55 45 42 44 Kleinfeld 80 64 60 58 45 40 37 41 42 38 60 50 55 48 49 38 42 36 36 35 Frankenstein.. . . 100 72 60 59 45 45 55 45 41 42 67 59 60 49 40 41 44 34 43 35 Brearman 144 94 56 61 48 45 44 40 42 49 79 57 47 50 39 41 37 37 35 37 Squad IX 3/1? 3/i8 3/19 3/20 EL EL EL EL Kramer 110 74 59 56 55 57 54 46 82 60 57 51 57 47 41 40 Frankel 146 108 114 63 64 65 51 57 110 78 65 57 59 53 50 49 Crowley 92 74 79 73 78 61 58 54 83 70 60 66 71 66 55 55 FuUman 129 84 71 70 59 59 53 50 113 58 62 53 48 46 54 47 Squad X 3/23 3/^4 3/25 3/26 3/27 EL EL EL EL EL Farrell 129 79 74 54 52 45 44 41 45 42 85 60 53 49 46 44 43 39 38 39 Lerner 84 57 48 56 52 49 41 43 36 38 78 55 46 47 48 40 37 37 38 34 O'Connell 130 114 64 67 54 60 55 45 55 44 101 99 63 62 48 56 59 43 42 41 Webber US 117 89 107 77 57 58 55 51 46 90 79 71 87 54 51 47 47 46 41 TABLE 9 Addition: Product Produced on Successive Days by Thirty-kine Indi- viduals 3quad I 12/ IS 12/16 12/17 12/18 12/ ig EL EL EL EL EL Grossberg 92 96 102 101 106 105 108 HI 119 114 Hanson 72 72 74 72 64 69 75 81 75 85 Schachter 68 78 78 86 88 98 94 92 97 99 Fried 91 103 108 109 118 124 131 135 134 137 The Effect of Conditions of the Air on Mental Work 19 TABLE 9— Continued Squad II 12/26 12/27 12/28 12/29 12/30 EL EL EL EL EL Schroder 47 46 45 48 SO 51 48 55 S3 55 Frey 39 40 48 46 50 52 57 56 57 56 Conlan 38 36 41 47 47 52 55 57 57 62 Squad III 2/2 2/3 2/4 2/5 2/6 EL EL EL EL EL Mantenband. . . . 68 69 75 73 82 83 86 89 105 100 Fisch 52 66 72 75 78 78 91 86 91 91 Tanz 54 58 69 62 60 69 68 73 80 72 Smith 68 58 53 64 60 62 68 65 60 74 Squad IV 2/9 2/10 2/ 11 2/12 2/13 EL EL EL EL EL O'Connell 39 44 41 S3 45 47 SO 52 S3 51 Kraus 45 44 48 47 55 60 62 63 64 66 Godmck 96 96 96 101 108 112 119 122 120 106 Enms 55 54 58 65 63 57 57 69 78 74 Squad V 2/16 2/1'; 2/18 2/19 2/20 EL EL EL EL EL Strumpf 58 65 71 65 70 73 72 79 81 83 Schatz 62 61 69 69 77 75 79 80 81 81 Deutsch 90 93 103 107 104 104 116 117 118 119 Margolin 64 69 85 78 84 84 94 91 86 98 Squad VI 2/23 2/24 2/25 2/26 2/27 EL EL EL EL EL Robinson 33 33 42 35 44 47 52 S3 52 48 Mendel 53 54 52 53 56 59 65 67 59 77 Klein 35 35 42 41 48 SO 54 59 47 55 Doun 61 67 67 65 66 70 64 82 85 90 Squad VII 3/2 3/3 3/4 3/s 3/6 EL EL EL EL EL Regard 91 92 93 101 105 100 113 113 113 115 Nemser 35 35 37 36 36 41 45 ' 42 47 49 Smith 44 47 49 51 45 42 51 46 53 62 Wallis 81 87 95 98 107 102 106 105 105 105 Squad VIII 3/9 3/10 3/11 3/12 3/13 EL EL EL EL EL Kuramerl 40 56 55 69 72 65 69 80 75 81 Kleinfeld , 72 74 83 86 95 98 104 102 107 111 Frankenstein.. . . 75 73 74 76 82 98 95 94 93 96 Brearman 60 63 65 62 74 75 82 85 88 89 E L 3/19 E L 3/20 E L 50 55 69 61 41 35 44 46 52 55 73 73 44 44 48 40 62 56 74 79 34 42 54 50 3/24 E L 3/2S E L 3/26 E L 3/27 E L 64 63 60 65 61 66 111 110 67 77 65 70 73 76 99 104 69 75 71 72 73 74 105 105 77 76 77 82 94 88 119 116 20 Ventilation in Relation to Mental Work TABLE 9— Concluded Squad IX 3/17 E L Kramer 44 48 Franke! 66 66 Crowley 37 37 FuUman 37 41 Squad X 3/23 E L Farrell S3 55 Lerner 59 60 O'Connor 39 65 Webber 103 102 TABLE 10 Mental Multiplication: Product Produced on Successive Days by Thirty- nine Individuals Squad I 12/is 12/16 12/17 12/18 12/19 EL EL EL EL EL Grossberg 20 28 38 45 52 46 58 60 66 65 Hanson 13 17 IS 21 44 26 40 20 30 25 Schachter 35 47 41 60 71 68 79 58 77 88 Fried 42 36 45 45 61 54 60 63 65 70 Squad II 12/26 12/27 12/28 12/29 12/30 EL EL EL EL EL Schroder 28 31 19 38 24 42 14 45 S5 67 Frey 40 56 38 55 74 60 80 75 78 84 Conlan 40 37 39 49 50 48 SO 41 S6 70 Squad III 2/2 2/3 2/4 2/s 2/6 EL EL EL EL EL Mantenband.... 49 52 72 71 85 74 70 80 78 102 Fisch 9 36 33 34 50 52 61 66 59 66 Tanz 50 74 84 79 92.10S 86 107 98 118 Smith 70 70 85 90 74 92 100 106 116 162 Squad IV 2/9 2/10 2/11 2/12 2/13 EL EL EL EL EL O'Connell 33 33 39 31 46 36 42 45 36 4S Kraus 34 37 39 46 ' 45 44 65 5S SO 52 Godnick Spurious results; used business "catch." Ennis 53 65 62 78 74 78 69 87 78 87 Squad V 2/16 2/17 2/18 2/19 2/20 EL EL EL EL EL Strumpf 26 59 69 98 83 81 88 102 86 90 Schatz 44 44 64 71 75 95 96 105 96 105 Deutsch 40 38 44 43 54 39 47 3 58 47 Margolin 27 SO 47 57 69 77 66 78 78 8& The Effect of Conditions of the Air on Mental Work 21 TABLE 10— Continued Squad VI 2/23 E L 2/24 E L 2I25 E L 2/26 E L 2/27 E L Robinson Mendel Klein Doun . . 20 16 . . 19 25 ..35 21 .32 39 25 21 16 25 38 30 52 55 35 28 37 52 29 29 36 44 35 39 25 33 50 35 43 56 37 33 37 38 42 41 57 50 Squad VII 3/2 E L 3/3 E L 3/4 E L 3/5 E L 3/6 E L Regard Nemser Smith Wallis .41 49 . . 25 22 . . 38 75 . . • 44 46 46 44 68 72 83 83 51 45 58 101 107 72 54 122 91 76 75 67 129 168 108 126 81 90 S3 58 164 160 123 124 95 95 Squad VIII E L 3/10 E L E u L 3/12 E L 3/13 E L Kummerl Fleinfeld Frankenstein. Brearman. . . . ... 10 13 . . . 30 47 . . . 47 76 . .. 24 31 33 45 49 47 69 67 34 40 35 53 65 44 30 52 68 48 42 48 41 57 79 88 51 56 52 49 40 49 73 70 61 55 Squad IX 3I17 E L 3/18 E L 3/19 E L 3/20 E L Kramer Frankel Crowley FuUman ... 23 38 . . . 33 36 . . . 34 55 . . . 16 23 38 42 34 58 66 86 15 16 46 68 78 19 48 64 87 32 57 52 60 83 154 101 32 44 Squad X 3/23 E L 3/24 E L 3/25 E L 3/26 E L 3/27 E L Farrell Lerner O'Connor Webber . . . 41 50 . . . 30 32 . . . 38 45 • ...31 12 60 51 45 59 45 46 18 30 70 58 48 28 54 79 53 29 76 89 77 93 52 70 28 42 84 73 96 79 77 72 28 42 TABLE 11 Typewriting: Product Produced on Successive Days by Twenty Indi- viduals Squad VI e'^-'l 2/24 E L e"\ 2/26 E L e'^'l Robinson 127 141 142 141 156 165 175 157 171 172 Mendel 27 43 48 49 63 60 56 56 68 69 Klein 128 143 141 144 159 159 173 168 * 161 Doun 47 52 53 66 56 75 76 70 93 89 * typewriter broke. 22 Ventilation in Relation to Mental Work TABLE n—Continued Squad VII 3/2 3/3 3/4 3/5 3/6 EL ELELELEL Regard 28 35 64 58 S3 7i 68 79 75 70 Nemser 76 71 78 82 83 91 86 93 93 94 Smith 73 79 84 102 92 96 104 102 106 108 Wallis 72 67 77 70 88 69 81 79 84 76 Squad VIII 3/Q 3/io 3/11 3/12 3/13 EL EL EL EL EL Kummerl 159 151 152 156 108 168 187 171 185 194 Kleinfeld 42 34 47 45 63 47 57 53 72 67 Frankenstein.... 44 63 48 51 56 59 60 73 73 76 Brearman 50 61 47 54 51 55 66 62 75 70 Squad IX 3/17 3/18 3/1(1 3 1 20 EL EL EL EL Kramer 48 48 49 53 59 57 67 38 Frankel 65 74 60 67 81 75 78 69 Crowley 79 75 68 65 94 89 89 73 Pullman 37 31 34 53 41 49 50 38 Squad X 3/23 3/^4 3/^5 3/26 3/27 EL EL EL EL EL Farrell 144 130 141 147 149 164 161 142 170 174 Lerner 83 89 80 93 84 105 107 100 107 109 O'Connor 103 108 102 HI 96 108 127 125 105 134 Webber 42 40 57 58 65 55 58 62 54 67 TABLE 12 Physical Condition: The Report on Successive Days of Thirty-nine Subjects as to Their Physical Comfort Squad I 12/15 12/16 12/17 12/18 12/19 Grossberg 2 4 4 3 5 Hanson 2 2 3 2 5 Schachter 2 4 4 3 S Pried 4 4 4 5 5 Squad II 12/26 12/27 12/28 12/20 12/30 Schroder 4 4 3 3 2 Prey 4 3 2 3 2 Conlan 4 4 2 3 3 Squad III 2/2 2/3 2/4 2/3 2/6 Mantenband 4 3 5 3 3 Fisch 34433 Tanz 3 4 4 2 4 Smith 3 2 5 4 3 The Effect of Conditions of the Air on Mental Work 23 Squad IV z/p O'Connell 4 Kraus 5 Godnick 4 Ennis 3 Squad V 2/16 Strumpf 4 Schatz 4 Deutsch 4 Margolin 4 Squad VI 2/23 Robinson 3 Mendel 2 Klein 3 Doun 1 Squad VII 3/2 Regard 4 Nemser 4 Smith 4 Wallis 3 Squad VIII 3/0 Kummerl 1 Kleinfeld 2 Frankenstein 3 Brearman 3 Squad IX 3/17 Kramer 3 Frankel 3 Crowley 3 Pullman 3 Squad X 3/23 Farrell 4 Lerner 4 O'Connor 2 Webber 3 TABLE 12— ■Continued 2/10 2/11 2I12 2/13 4 4 4 4 4 4 4 5 4 4 4 4 3 4 4 3 2/17 2/18 2/1Q 2/20 3 4 3 5 3 4 3 5 4 4 3 4 4 4 3 4 2/24 2/2S 2/26 2/27 3 4 3 4 3 3 4 4 3 3 4 4 1 3 4 4 3/3 3/4 3/5 3/6 4 3 3 3 4 4 4 4 2 4 4 1 4 4 4 2 3/10 3/II 3/12 3/13 4 4 4 4 4 4 3 4 4 4 3 2 4 4 3 3 3/18 3 ho 3/20 2 4 4 3 4 4 2 5 4 3 3 4 3/^4 3l2S 3/26 3/27 3 3 3 .3 4 4 4 3 4 3 4 3 3 3 4 3 EXPERIMENT II THE EFFECT OF CONDITIONS OF THE AIR UPON THE RATE OF IMPROVEMENT OF MENTAL FUNCTIONS By E. L. THORNDIKE and W. A. McCALL* The resvilts reported by Dr. Chapman (pp. 1 to 23) for the ex- periments with daily change of air conditions show that when a per- son exerts himself, his achievement at mental work is as good under various bad conditions, up to "No fans, recirculated air-supply, 86° F., 80% relative humidity," asunder the best conditions (45 cu. ft. of outside air per person per minute, 68° F., 50% relative humid- ity). The results of the experiment now to be reported show that the same holds true as between the worst and best conditions, when each is maintained for four hours daily during five successive days, and that the improvement made during the work of a "bad condition" week is equal to the improvement made during a "best condition" week. The two conditions mentioned above were contrasted in the case of 15 subjects, college students, each of whom was subjected to one five-day period with the bad and one five-day period with the good condition. Eight had the good week first, the bad week immediately following. Seven had the bad week first, the good week immediately following. The time was four hours in each case, though only about two hours were given up to the mental work, the balance being re- quired for the physiological measurements that were made. The physical conditions in the experimental room were maintained only approximately as stated above, because the working of the plant required recirculation at times to maintain the high tempera- * The first author is responsible for the plan of the experiments, the prep- aration of the material, the statistical treatment of the results and the report here made. The second author is responsible for the administration and scoring of the experiments, and concurs in the conclusions of the report here made. The maintenance of the physical conditions for these experiments was as in the series reported by Dr. Chapman. 24 Effect upon the Rate of Improvement 25 ture and humidity, and because of other minor difficulties. In view of the general result of the experiments (which was negative), these minor irregularities are of no importance so far as concerns the psy- chological problem investigated. The room conditions during the experiments were as shown in Table 13. The instructions and all other conditions, save those of the air, were as nearly identical for all the fifteen as Mr. McCall, who con- ducted all these experiments, could make them. The details of the administration and scoring of these experiments were the same as those reported by Dr. Chapman. The scores to be reported here are thus measures of the quantity and quality of the product pro- duced, representing a fair combination of the individual's speed and accuracy in the number-checking, addition, mental-multiplication, and typewriting which were the forms of work done. First, we may compare the gross total efficiency of the work under the bad and the good conditions. The facts are shown in Table 14. The product produced (with allowance for its quality) under the bad condition is thus 97 per cent of that produced under the good condition in the case of checking numbers; 106 per cent in the case of addition; 102 per cent in the case of the very difficult mental rtiultipUcation; and 102 per cent in the case of t3^ewriting. The result of the "one-day-four-hour" tests of Experiment I (that mental efficiency at maximal exertion is unimpaired by the bad air condition) is thus fully corroborated by these more elaborate experiments. They also show that the bad condition was as favor- able as the good, not only to temporary efficiency but also to improve- ment from practice. For there was, with all subjects, great improve- ment during the ten days; consequently, had the good air condition been more favorable to this learning process, its effect must have appeared in the quantity and quality of the total product produced during the good air condition compared with that produced during the bad air condition. There might conceivably have been certain subtle compensating conditions masking an effect of the air on human ability to improve. There was no such effect, however. A full analysis of the actual course of improvement from day to day under each condition shows that any differences in the rate of improvement are probably acci- dental and are surely as much in favor of the bad condition as of the good. We present this analysis in the form, first, of curves showing the efficiency of each of the functions or tasks at each successive period, and, second, of tables repeating the facts numerically. 26 Ventilation in Relation to Mental Work TABLE 13 Recorded Room Conditions during Experiment II ^ •Cv. to •I -a 8 f' 10 8 g to t Cj H «^ O N -ft. < to March 30 2 31 April 1 2 3 April 6 2 Recirc. 3 7 8 9 10 Fresh Recirc. 37 37 37 44 42 51 48 52 46 50 68.0 68.5 67.5 67.5 68.0 39 76 86. 5 39 72 87 39 79 86 39 78 86 39 79 85.5 4.0 5.0 5.0 6.9 < ' April 13 2 Recirc. 3 3 Recirc. 14 " " 15 16 17 April 20 2 4 2 2 Fresh 21 22 23 24 39 71 86. 5 49 78 86 39 78 86 39 81 85.5 39 79 86 45 58 69. 5 46 47 68 46 53 69 45 48 70 44 48 69 3.8 7.8 3.5 5.2 May 18 1 1 3 3 No. sup 81 86 19 " " 81 85.5 20 " " 81 86 21 " " 81 85.5 22 " " 80.5 86.5 6.1 38.3 33 52 68.5 45 52 68 45 54 67.5 45 49 68 45 50 68 May 25 2 4 2 2 Fresh 26 27 28 29 4.6 5.2 Columns i to 4 show the standards which on each day the operator tried to maintain. In column i, under "motion of air," i=no movement save what the subject and experimenter caused. 2=no movement save what the subject and experimenter caused and also that caused by the ingress of air at the rate shown in column 6. In column 2, under "nature of air supply,' In column 3, under "humidity," In column 4, under "temperature,' i=no outside air supplied, or practically none. recirc=recirculation at the rate shown. There was leakage as shown by CO2. 4=45 cu. ft. per person per minute approxi- mately; see column 6. 2=So% relative humidity. 3-80% " 2=68° F. 3=86° F. Columns 5-10 show the recorded room conditions. Columns 9 and 10 are averages for the weeks or fractions of weeks in question. TABLE 14 Gross Total Efficiency 2's cancelled (with allowance for errors) 3's cancelled (with allowance for errors) Columns added (with allowance for errors) 3-place numbers multiplied men- tally (with allowance for errors). Amount typewritten (with allow- ance for errors) Under good condition. 45 cu. ft., 68°, 50% Under bad condition No fans, no air- supply, 86°, 80% 22,853 21,411 21,931 21,909 12,788 13,518 17,152 17,564 46,604 47,447 28 Ventilation in Relation to Mental Work Consider first Fig. 1, which tells the story of the average ef- ficiency ih successive days in checking 2's, of the eight subjects who had the "good condition" week first, by the height of the continuous line; and the same story for the average of the seven who had the "bad condition" week first, by the height of the dash line. The reader should examine this diagram and its explanation with some 180 i70 160 m 140 J50' m no 100 90 80 70 60 TO 40 30 19 10 » E 3 4- 5 5 7 8 9 to- 41 -«. 13 .14 V5 16 17 18 i<3 20 Fig. 1 care as aU those to follow are drawn after the same plan. Lengths along the base-line represent amoimts of practice, each two succes- sive divisions representing one successive day of the experiment or 120 seconds of work. The height of the curve represents the effici- ency of the work. There are thus two points for each of the ten days, two tests of 60 seconds each having been made daily. If the good air condition had been the more favorable to improvement, the con- tinuous line should mount rapidly during the first half of its course Efed upon the Rate of Improvement 29 and then much more slowly; while the dash-line curve should moimt slowly during the first half of its course and then much more rapidly, as shown roughly in Fig. 2. As a matter of fact the continuous line does not rise quite so rapidly during the first half as does the dash- line representing the average of those then imder the bad condition. During the second half, when the group scored by the continuous line were under the bad condition, their gain is a little less than that Fig. 2 of the contrasted group, but the inferiority of their gain is no greater than it was when they had the good air condition. As a whole, then, the differences between the two curves are explainable by the simple fact that the "bad-condition-first" group made on the aver- age more gain in cancelling 2's than did the "good-condition-first" group. They did so as much under one condition as under the other. The effect of the air condition seems to be absolutely nil. There are ups and downs such as are always found in mental work, and these variations from day to day, or from period to period of 30 Ventilation in Relation to Mental Work a day,* are large, showing that the function in question is susceptible enough to some conditions. But the air condition shows no effect. Fig. 3 shows similar facts for checking 3's. The course of im- provement bears no positive relation to the air-conditions. The dash-line group, which had the bad air condition for the first half of the curve, gained more than the other group did in its first half, and }6« m 140 130 120 no m ^0 59 ?P 4a 30 EO Iff I 2 3 4 5 6 7 9 10 11 a xb in. 15 16 n la w 20 Fig. 3 did not gain any more than the other group when conditions were reversed. So, if the facts are taken at their face value, the bad con- dition seems somewhat more favorable to improvement. This, how- * The curves do not show the same chronological day at the same points, since the tests were made in four separate series with squads of four subjects per series. The same point on the continuous line is due to an average from two days that were two weeks apart, and the corresponding point on the dash line is due to an average from two still different days. The variations of any one chronological day from another for any one subject are far greater than the variations in the curves. How great they are will appear from the tables to be shown later. E_ffect upon the Rate of Improvement 31 ever, is probably a chance result due to the small number of sub- jects, as will appear later. Fig. 4 shows similar facts for addition. Here there is a consider- able balance in favor of the bad condition. The continuous-line group gains notably imder the bad condition; while the dash-line group gains little under the good condition. In the first half of the coiirse of practice when the continuous-line group was imder the good condition, and the dash-line group was under the bad condition, the gains were indistinguishable. 100 .^^-ocr: My condition is about half way between 1 and 3. 3 = 1 = n Effect upon the Rate of Improvement 35 • w CO O ^ D S 1^ ooooiorc "*o>>Oio t, o •^ C 2 "O OJ S . 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Effect upon the Rate of Improvement 37 C vo (M ^o »») NU -^P \1J> WJ 5i^ 1^ "4 °°^'^"> rot^ioio -C Ji-C S , nooo-H Novooo'* SS r*^ '-^ oovovoro "5t^o ■Be ,, ovotstM tM'^vo'* 03 < " }i OvOTt*0 00 VO 00 vO s^ kq ^ThVOTfl (MiO,-o V3 XI d oOOOtH VO (M rH O >>8 ft] ■oio^oio CN vo POiO 1-1 i-H ^-H T-i ,-(,-4 iH'^ 'O 10 o »o ooo\o OOTt< OOO § 1-^ t^liO VOID O fOi-H (^ 00 . T-< »H iH ^-H ">2 ■>!< •*r tJ* 00 00 m OOO O 00 3 6 **-^ Kl \0-^iO ro rD -^ Tt* Tt< m O tH T-H 1-i i-H 1— 1 iH ■*-! iH ja'-S § OTS ni IS ■<* es eN-<-i fs vo O vo rg u o M VO-^IO (T) (N TtfPT) PO g^ •. •^i-tiH vH iH tH i-( T-( ~5 vO-«*Tt)0 O c*^ Kl lOTh lO ro CNJTJH fO PC o ■^,-( T-H ■rt tH iH 1-1 i-( l4 (ti a, - o .>< o (N (NCO'<* \0 \Ci 00 o ■ 5^ i~5 »0 roro CN (M CO OJ CM ."" ^ ■rH tH 1-1 1-1 1—1 1—1 1—1 tH t^„ ^-t u S O rq CM 00 (N 00 VO CS §« K! iO(D ■<* 0\ esi PO » •T-i m ^-( e(U VCPOO QOOOOOtJHOO g "I (£| l^Tt^Ov IN'OVOCN IT) •dnj „- l-J t^rot^ tsr-t-lM lO S^ § -^-^-^ ^-^^ -1 -a ■"-' .On aji*_( ^ ooioo csoo^oo OS ^ o S-, [jq so »o 00 fOt^t^<>J i'^ O -O^ ^ o'"r5 OOO ©■"foOOPJ 3 C! ^ fd »D CO 00 CMIOCOCM ■* (O O O ^ ^ tH ,-( 1-H ^ 1-H tH rt e 5 ooooo o CM 00 CM t^ ^O S K] COCOU^ CM UT* ^ CO Ot3 CO — I O i2 TflTjcO SOTfTtlC^l CM^ so ■=< W "^OsSO -HTfTfCM CO Ubfl "^,-HtH y-t rH y~t ■^ y-t 2 " is £■".2 CM-*C-) CMSOCMOOO •^- "^ J COOC^ OCOCOCMCM O C3 8 33 r^^ Tt<00CM OOOOCMIO "O ^»J fd CM O so O CO CM CM CM t-t 3 ■«» D-i rt -"i! -i4 *e •* 00 O CM 00 CM O Os CO ^ tH g 2 W (MO-* OSCOCMCM CM ^^ t35r^3 e3 0(urt g Effect upon the Rate of Improvement 39 2 Ov-^OvO oo-^-^to fO .e 1^ Tt< PO 0\t^ O-ir^^ -M ■f-H 1-1 ^1 o o ■•-1 CS vo O r^ NO 00 CO On C m 00 ttl lO (N 0\0 OnO . f^OOOO t^'^ 00 f-^ ^_, ■^ 1^ lo ra o O OO^O T-l, tH »-( 1-1 T^ ,_( ,-t 1 a\ COOvOiO CO On On lO lO Kl ■<* wO\0 OnOn^O o o T-< T-l o o s P m t^ Mt3 8 O CN t^ J-^ J>- o-^-^ t^ D O ,a h^ U-) cs On ^O CnO(MO o ^■n ft. 1-1 -r-^ :s. ^ CO CS OOCO -^- 0-«* 00 cs o •SS ttl ■^OOOVO OnOn^O o 1—1 1—1 1— ( 1—4 T-l C C!i ^ 3 — s •s'S ■^lO fCt- '>!t* li-) NO On o 1J 13 •« M CO O 0\0 On On 1-1 On o -a T-l T-H g-^ 8 *-« O I* O fOTi^NOPO Trji lO ■'^lO NO W Cc5 ro O OOO i-( 1-1 OnOOO On On o 1^ OiOOO-tH 00 NO CO O NO fOO On^ oOOOi-t oo On 'ti 0) 1—1 iH S w ^^ ^c 0\ ^t^ On lOlO CN ON CM 11 Kl csoo\»o iH 1-1 ooooo t^ On jgftq pa < bfl OOPD CM*^ On*^ oo 1-1 J^ 2-^ J3 ^ »/: M CN|0\NO-^ CO00Tj*t^ OOOOO 00 1-1 OOOOIO 00 NO O ft] ■»-H OOOMO 00l>- O 00 1-1 QO >•&< o •O S lO CO Th c-oco On»0 Tt* On NO >. (U oo" •^ (N On 0\iO 1— ( 00 ^ J5 VO -a'5 •* r OJ Lh ^ OnOC^^ MTtiNOr^ t^ > o •<-i Kl CSOnOOIO 00 t^ O o- 00 .!:h<^ 1-1 (0 8 " o b-s ID OvOnO^O On 00 On NO CM SI H ■^i>-GO'«* t^ NO Ot^ 00 •o P, 8 c^ o o o ■^iOl>.*^ CO ■* -^t- NO ^.a :•§ Kl -Ht^t^rJ* t-^ NO On NO t^ a " 1 o CO O 00 CO 00 O cot^ ■^ ■fe i~l NO NO On NO t^ O . cs 1 O Tt*iO CO 00«O 00*-* Tt* ^1 Kl (Nr^i>. Tt< NO lO 00 NO t^ ^J a On CO r4 s K5 ON^NOi^t* in -^ t^io NO ^1 ^ 2« i-s »-i W 1 "g-Sf.-^ > Squad Kuen Rivl Stac Zuck 1 a < CiuH 1-1 OJ 0) 0) -^ 40 Ventilation in Relation to Mental Work 4) ^^ lO rO o .S en Kl lo cs CM vo cs cs O .^* b-p o\ •So § •T3-0 PS VO tH ^§ r ^ «25 i-^ c^OO Is ^ S ii , VOOO 3 K^ o 00 -SI I ^ >S tt] ioooo\ c^o^c^'o o o 2 3-s ,53 1-0 looot^ ooOnOnO ci'rt On 00 1/^ cs vo to lo S 3 S jj ■« "art < to paWt/3 Co taOi-)N Effect upon the Rate of Improvement ■ 41 ooorq (N _ ^ CNl CS fO •OT3 o o g^ _^ T-i th »-i ^-H ^H oi ro Is ^ rt ?^ ooot^M i^ 00 Ov -^ 3"" "^ l^ 00 00 ^ ro t^OON^ -Q -^ 5^ 1-1 ^H ^H CN tH C<) c c g = ooomm M O\00-*-H T-4 tH o o r-^ O Oeo Ov CO ^ oovr-o T-l tH »-l 00 o ^ 00Ol~M ^ ^ OOOO'^rO t" O to t^ioor^ 1^ 0»0\ fO cs *H ^-H to" 8 oooo ,e h^l O ONiOCN fe, »-( »-l tH rOOv^'* csro T-i >> W OvCMOCN 0000-rtO ■^ •— < Q ^ aBd ^^ ■■d .^ ^ki IV^ is O 8 OOOvO ror^fOT**^- -•-» Q tO OOviOC^I COCOOO^ VO Q ^^ C^ »-c WtH ^ ^ CS CS| *-h OJ ^J .. i-H tH 1-H ^-* T-t CS ^^ *5 -^ O\cooov oot>»o\*0»r> ill ^ rt to OO Os 0\ O rCeSON*^ « 4j ft] 0\0\(NeO -rJHCOtnTH >.5 ^ — — ~ »-l tH ■»-< OJ M 'O C O 0^ ^ CO r* CO O lO w (M ^ rovOCSOO lO (T) 0\ Os OOVOVOOO i-H CO ro 00 4->0 O r>-T OOOGOOv t^t^OiO 00 = ^ ;g - - -- O -w S J) (3 -fe 'H -■ zS.3 ^ "^ g lO _^ rvi "*0\«^rt -HlOOm 0\ " O S O lOIO-HVO OCNO>rs t^ " o e<.t;J2 '~' >ot»5(Nio ootj ^ a 2^ -t->.iil o h"^ >o (U c! ■o § 00 e " VO 3^ -. •ofe ^ OJ V •to § o *' ^s oti ja u a •3 -a ol c T3 3 5 8 1^ a ^ . .Sj< '^ ■a ci J3 i> +J ^>2 ••a s a &I CO •^i 1-i to U o w g^jH CO J \o P3 oo t o # ■e. J3 1 O 1-. dj o T3T3 g <4 C 3 3 •OT) 1 2§ a O ■!-> s U CO o a,,S 1 :-S 0)' O u 1 m K ■& ■c "« 4 ^H th OOt^ Os rfJt^fO O fd O O CO lorocMi-* a oa o a 3 o 5) ni Rffect upon the Rate of Improvement 43 .C^.O tO OOO Tf»0 ■*■* CNfTt fOfO vOt^ Tj4-«;t* O^O O **- <***-< ^ es^ y-i^ ^^ ^,-1 T-H^ ^th fiT-i ^»-i ro '43 ^u * KJ ■*■* '^'^ tn"^ \ oor* ro»o toro lO "O OO -^ fO -^00 »-) ^ ^4 -O*- .^* o esiro fO-^ -^^ -^c^ '^in vo\o forg torn ■^ "S o Jr^ "S* «^c^ -^"^ ^'-' '-''^ "^"^ "^"^ ■^'^ '""^ '^ fc« Q. ex Co *^t^ -^ ff) ^O) Ovr* too -^ro rf)*H \0 00 eO •-^3 '' M OCS rONO Tj*»0 CS (M ■ C rt . k, r^M ■r-4-.-t -H-pH tHi-H ■.-Hl-I -HW ^^ ^-^ CSJ 3 >.^ o CO l?cd1;;J ^ W ^^ ■<*'"^ ^"^ f^-* f*^f^ t-vo po(M "*io o Sv2 .. ^ cs CS '^■^ ■»-ith '^1-1 ^ 1-H i-(-H th th 1-h ^ ro ^"•^m "^ O'-Hr*O>0P0O\t0 *-*!-* OstDOOOOrcvO 00 _0 -^ kJ -hO\ ■^ro Tt<(N (MCS lO-Tj* O*^ T*ifO Tt*rO Ov O ^J V ta ^ r^^ ^^ tH^ ^,-t ^*-i iIth tHt-* ^-^ «N - ?J_- fd oo» -^ es fo cs poco CN CO Tt*i>. ^ po po tj* oo •S "^ .fc: ^ CSjT-C '.-H-^ -^T-l ^*H i-(-rt '^▼-t -^v^ vH ^ CN -^ c oD 'S O NOVO ^O fO t^po •-(po *-*Os ^*^* r* 00 oovo ~ 2 O ^ i—Sf^ rr^m .^rr^ ror>j *^r*J ^Hro v^r^ (NlfTi o ^ O po po po 1-1 po rq cfl cor^ ^ cs i-*c^ csro oo PQ CSCS -^-^ ^'H *-l^ THi-t ^-^ ^-rt *-4^ CN O^ 1-1 vO OO PO Tjt PO oo 00 "O '^ O O PO o j-> .-H frf OOO es es cs po cs po po po vo»o O r^ po ^ oo jS^,ii ^ i-tCN i-Hi-H ■^•H i-tT-K ■»Hr-l i-(i-t ^1-H i-i--H CS til —So ■^t^ (SO "O es eso* *^0 poos o o\ ,53"'^ "-ftS OOTf "Hr^ >-4T)l t~o\ fo-^ — <« VOtJ< o lu o-S .^ k-l O'^ mr^ 0-* t^'H tool • -h— t~ .§•33 S "" '^'^ '^'^ ""^ ^'^ '"^ " -- cs See -^ •*'^ ""S f-oo Ot~. r~co OOO (MM pq o\ CO gS-- ^ M OvO> O-H -HO -HO "lOl fTim 0\Ch CMi-1 ■* o o j3 S u i2 ^-<^^ o»~ o vo '* 0\ cst~ oo>o t-o o. -h o> u\r a, ^ i~? OOO* -HO -H-H oo O'rt csfo ovoo o-h "^ rtJJ., m .. -4rt-HTH-HT-l-H--l rt-H— l-H _<^(N o 5 cs ^ .w i« rt 0) S 12 o. --.2 ^ CU 1-1 C u «3.0U3 H S Id b H K| (NPO iH 1-* •^Ov 00 On ooro 0\0 -H moo OvOv OvO T-t OS POSO POTj< 1-t 1-1 O fO 00 o\ 0>-H -H«M vo CS 1^ 00\ *^o wcs g2 — H «H OO rovo 00 Ov g2 1-t 1-1 \oo ■^ PO OOOO 22 o n es bl 00 vo vOpO •H 1-1 CSO\ OsO> 00 00 S2 -H -H -HO r^fO 1-1 i-H 00\ iH i-t o cs M *OoO \o »o 1-1 1-1 *^ OO 00 0\ 00 0\ \00 OOOO 00 PO »H es 1-1 tH W5VO vOiO 00 00 s K| >-i lO 1 d 3 5 u 3 N ^ ^ 44 Ventilation in Relation to Mental Work M b^iS >A POO rOCN OO ro*^ iO»0 lOt^ CNP"! O ^^ !?^^ CSCS CNCS f-lT-t eN(N CNCN ■^p-l^ ■^»-« -^ g O g o -O ,^ kJ 00 0\ (NiO t^ 00 -^ ■<** vot^ O^OO r^rt* »h "^Ofe S 'HW CNCS ■^»-( (NOJ CNCN ^H»-t tH'.-C -«*< ^ a = n *i ,^ Tj-iO -^oo *^Q0 POfO O H5^" •■ MtH (NCS t-h»-i (NCS M r^ ^'^ r^VO O^-t*! 00*^ -^^ T-(CO Tt<0\ O ,SHT3 § W O O «0*0'*'nmr»5tO>0 C p- &?J3 cs '-^ (N C^ i-( ^ ■ es *H «s CSI ^H ^ es cs cs cs --h ^ ^h th co Wt^-*-*-. S r, f*5*^ <^^ 0\0\ cso c^c,ti: +j o " 2Ji ?S irj O vOO\ 0000 cor^ Ti< CS ■^ cs U^ o^ i/^ ?J^a '^^ t^ oOOi CSO fO-^ fOTjH i>.io TJ^^o •-i'^ \0 ^■i;^-? "r^ ^-H ■»-( cs cs ■^^-1 rq cs cs cn i-h th ^ '^ ro CJO.S On ,, i-hO\ Tjipq ■^O ■^irj cs»0 <-hO CSsO O y w •* M o\*^ cs '^ cs to o cs ■^ lo coco oo *^ o^t3 o ^ ^^ c^cs ^^ cscs cs cs ^^ *H^ to 3 ^ O K CO 0m ft, ^H'l-H cscs ■^i-l cscs cscs -^^ T-ti-H CO oI-.K^ >; ,^ t^OO lOTt^ O*^ ■^O IOCS] OOCO iOO\ ■^ -SiT) C f^ *^^ ^"^ "^"^ ^*^ "^"^ cscs ooo so •CJ^ C a1 •. fH i-H (N 1-1 TH ifH cscs cscs iH tH ^ ro Ti'O'^cj ^a »-iio ONO\ »-i\o ■*tTt< t^o\ poo\ mirt *H oCjS— :s i~3 ooo ■MCN <^tJ< oo rs>o tH»-i o\o\ t)i t. ti) S a ^ ■^■^ "'^^ '^■^ ^<^ t^ix '-'■^ « +J-^, o'm O ,, oot-* lOO t^io voo *^t^ p^fo t^Os O^ HSioi'S ^ 1*1 -^^ '^'^ "^■* °^°° O"-! ot^ oot^ o CtfiSe" "2 i^O\ o\>^ Tfo ot^ cNro 00^ oovo \n ^ OIX3 fS 1^ Tt< f*5 00 0^ ^ ro vot^ ^^ O 00 00 *^r^ oo ■ - K] rt^^T-lrtrt ^^(NCN CN • OJ S OJ 2; -M S -w ,, ooo •200 -o># m^sf ro o ooo »-i o os JH Cd CN Condition 6 7 8 9 10 3.6 3.7 4.0 3.6 4.3 4.7 4.3 4.7 4.1 EXPERIMENT III THE EFFECT OF CONDITIONS OF THE AIR UPON THE ACCURACY OF JUDGMENT By W. A. McCALL and E. L. THORNDIKE In Experiments I and II, the subjects worked, presumably, with something approaching maximal effort, the incentives being their fixed daily wage, the instructions of the experimenter, and competi- tion among themselves. Not only did they have a general notion of how well they were* doing in each test, but each day they were given the scores made on the previous day. The purpose of the experiment to be described was to ascertain the effect of conditions of the air upon mental work when the in- structions of the experimenter, the conduct of the experiment, and the nature of the tests were such as not to stimulate effort but to encourage carelessness. The tests were made upon four young men (students) who occu- pied the experimental room for six consecutive weeks, five days to the week and seven hours to the day. Six air variables were em- ployed, each air condition lasting one week. They were: No fans 1st week— 68° F. 50% r. h. 45 cu. ft. 2d " — 86° F. 80% " " No air 3d " — 68°F. 50% " " No air 4th " — 86°F. 80% " " 45cu. ft. 5th " — 75° F. 50% " " 45 cu. ft. 6th " — 86°F. 80% " " No air The schedule for each week was: For Mondays, Tuesdays, and Wednesdays 9:00-10:00 a. m. Physiological tests 10:00-12:00 a. m. Psychological tests 12:00- 1:00 p. m. Lunch served in the experimental room 1:00- 3:00 p.m. Psychological tests 3:00- 4:00 p. m. Physiological tests For Thursdays and Fridays 9:00-12:00 and 1:00-4:00 Physiological tests 46 Effect upon the Accuracy of Judgment 47 In the psychological tests, the subjects were asked to assign values to certain intellectual products. These intellectual products were specimens of handwriting and composition. The specimens of handwriting and composition had a quality range of from very nearly the worst to very nearly the best. About 10:00 a. m. each subject was provided with 110 specimens of penmanship and was asked to assign to each specimen a value according to the Thomdike Scale for Grading Handwriting. Following this he was asked to do likewise for 20 specimens of composition according to the HiUegas Scale for Grading English Composition. Before the six weeks of the experiment itself, the subjects were given preliminary practice in the form of judgment required and in the use of the scales. The above constituted the work from 10:00-12:00 a. m. In the afternoon, the program was exactly the same. The experimenter was provided with 1320 specimens of pemnanship and 240 speci- mens of composition. There were so many specimens and they were rotated in such a fashion that it was impossible for the subject to remember the values previously assigned. It is evident from the nature of the tests employed that no subject could tell at any one moment just how well he was doing. Also, the work was intentionally made drearily monotonous and barren of interest. No scores were given throughout the entire test. The subjects were never urged to accuracy. Their names even were never known to the experimenter. Each man had a symbol. Care- lessness and laziness were enhanced by giving them twice the time necessary to complete the assigned task. They could cease work at any moment and go to sleep if they wished, provided the assign- ment was completed by the end of the period. During the two-hovu: psychological test no general conversation and no comparison of grades were permitted. The experimenter did record the time taken by each individual for each section of the test. He also made obser- vations upon the general reactions of the subjects to the work and to the air condition. This was done in such an unobtrusive way that it resulted in little or no stimulating effect. The pmpose of the experiment, it has been said, was to measure the subjects' accuracy of judgment imder various conditions of ventilation. In order that this might be done it was necessary to determine the true value of each specimen graded by the subjects. Given this, the accuracy of each judgment could be measured by finding its divergence from the true value. Of the 1320 specimens 48 Ventilation in Relation to Mental Work of penmanship 1200 were carefully graded by 21 competent judges and the median of these 21 judgments was taken as the true value. In order to make sure that 21 judgments were sufficient to give an adequately reliable standard, the other 120 specimens of penman- ship were graded by nearly 100 judges. The subjects' judgments on these 120 specimens were scored and are reported separately. The similarity of the average error for the 120 specimens and for the 1200 specimens certifies to the reliability of the standards derived from the 21 judgments. The English composition standards were the medians of the judgments of about 20 individuals. These individuals were the most competent of the graduate students specializing in English in Teachers College, New York City. In order to measure the reliability of these standards, about half of the 240 specimens of English composition were graded by many more judges. This resulted in some cases in a very, very slight displacement of the pre- viously obtained standards. In each case the scales used by the sub- jects were used in standardizing the peimianship and composition. The recorded physical conditions maintained during the course of the experiment are shown in Table 21. It will be observed that in this experiment there was no recirculation at all. Either an abundant supply of outside air was introduced or the room was left as com- pletely sealed as possible. High CO2 percentages were obtained. This was not the case in Experiment I, and was the case for only part of the time in Experiment II. Using the penmanship and composition standards previously men- tioned, the error made by each subject in his judgment of each specimen of penmanship and composition was measured. The average error for each subject for each half-day was calculated. Continuing the combination, the average error for all four subjects for the three days during which they were subjected to any one condition was found. This average error is the efficiency measure for that condition. The smaller the error, the greater the accuracy of the judgments. The measures in Tables 22, 23, and 24 give re- sults for the six air conditions for the fimctions studied for the time indicated. If an error curve were drawn according to the daily averages of the four subjects and this curve were smoothed out, the result would be very nearly a straight line. This means that no allowance need be made for practice. If the function improved, the improvement was oSset by an increased boredom and consequent carelessness. Effect upon the Accuracy of Judgment 49 Date TABLE 21 Recorded Room Conditions during Experiment III 12 3 4 5 Cu. ft. per person Tern- Air per Humid- pera- Fans Supply min. ity ture CO2 parts per 10,000 Beg. Mid. End 6/8 No F 45 63 68 6.5 6/9 (( F 45 51 68 5.5 6 6/10 {( F 45 57 70 6 4.5 5 6/U ** F 45 57 67 6 4.5 5 6/12 It F 45 62 68 g:oo 6 11:30 6 2:00 3:30 6/15 11 None 76 86 19 31 6/16 " 79 86.5 4.5 30.5 29 6/17 II 71 87 10 8.5 29.5 6/18 " 81 85 9.5 21 29 17.5 6/19 " 82 86 11.5 31 36.5 29 6/22 " 54 69.5 8.5 31 40.5 44 6/23 II 50 67.5 25 39.5 32.5 6/24 tl 51 67 15.5 23.5 31 32 6/25 " 54 66.5 11 57 54 54.5 6/26 " 52 67.5 15.5 42 51 47 6/29 " F 45 70 84 12 6.5 6 6/30 tl F 45 79 86 7.5 7 8.5 5 7/1 *' F 45 80 86.5 5.5 6 5 4 7/2 " F 45 80 86.5 5.5 10.5 5 7/3 " Experiment omittec I 7/6 II F 45 54 74 6 5.5 9 7 7/7 " F 45 56 75 4.5 8 9 7/8 " F 45 63 75 7 18 6.S 6 7/9 " F 45 68 81 8 17.5 8.5 7 7/10 " F 45 66 81 5 21 7.5 7 7/13 " F 76 91.5 19 7/14 " F 79 90 4 11 19 19 7/15 " F 80 87.5 5 18 15 20 7/16 " F 74 86 7 35 29.5 33 7/17 II F 81 85.5 3.5 32 34.5 30 A glance at the average errors shows that this mental function of judging the value of intellectual products was a highly variable function. It varied, but it varied irrespective of the air conditions. An individual may make very much larger errors at one period than at another, but the hot, humid, stagnant periods show no larger errors than the cool, fresh periods. There is no demonstrable effect of heat or CO^ content. Tables 22, 23, and 24 may be taken at their face value; for the amount of the errors varies irrespective of the speed of the judgments or their time location in the six weeks. so Ventilation in Relation to Mental Work These tables then show that, in a very variable and sensitive function, the quality of the judgments is as good when the air is 86° as when it is 68° or 75°; when the outside air supply was reduced to as near zero as possible as when 45 cu. ft. per person per minute was possible. Further analysis shows that there is no demonstrable difference between the quality of the judgments early in the day and later which can be attributed to effect of heat or CO^ content. TABLE 22 Long Series Handwriting. Average Deviation <5S° F., 50%, 45 cu. ft. no fans 86° F., 80%, no fresh air, no fans 6/19 6/10 6/11 6/15 6/16 6/17 E* L* E L ELELELEL B.R.B. 1.711.99 1.15 L 33 1.26 1.10 .62 .78 .66 .64 .64 .57 E.M.J. 1.23 2.02 2.52 1.62 1.98 1.57 1.29 1.89 2.29 1.54 2.07 2.49 J.S. .85 1.06 1.23 1.30 1.33 1.43 1.63 1.14 .93 .83 1.13 1.00 J.U. .79 .74 1.03 1.25 .95 1.64 1.15 1.68 1.311.74 1.96 2.10 Total 4.58 5.81 5.93 5.50 5.52 5.74 4.69 5.49 5.19 4.75 5.80 6.16 By days 10.39 11.43 12.26 10.15 9.94 11.96 By weeks 33.08 32.05 Average 1.38 1.34 Condition: (55° F.,So%, no fresh air, no fans 86° F. 80%, 4$ cu. ft. no fans 6/22 6/23 6/24 6/29 6/30 7/1 BLELELELELEL B.R.B. 0.68 0.93 0.58 0.67 0.59 0.55 0.610.49 0.57 0.46 0.62 0.52 E.M.J. 2.70 2.42 2.612.31 1.97 1.84 2.312.07 1.97 1.90 1.90 1.99 J.S. 0.81 0.85 0.88 1.00 1.18 1.24 1.03 0.97 1.14 1.06 J.U. 2.13 1.89 1.72 2.09 1.92 1.67 1.59 1.90 1.77 1.76 1.88 1.90 Total 6.32 6.09 5.79 6.07 4.48 4.06 5.69 5.70 5.34 5.09 5.54 5.47 By days 12.41 11.86 8.54 11.39 10.43 11.01 By weeks 32.81 32.83 Average 1.49 1.37 Condition: 75" F.,50%, 45 cu.ft. no fans 86° F., 80% no fresh air, 5 fans 7/6 7/7 7/8 7/13 7/14 7/15 EL E L E L E L E L EL B.R.B. 0.60 0.58 0.610.62 0.610.48 0.56 0.50 0.610.56 0.58 0.53 E.M.J. 2.23 1.84 1.82 1.72 1.78 1.67 1.65 1.47 1.51 1.89 1.50 1.54 J.S. 1.09 1.35 1.55 1.32 1.33 1.24 1.88 1.54 1.29 1.09 1.13 1.40 J.U. 1.92 1.96 1.92 2.08 1.33 1.61 1.36 1.55 1.68 2.13 1.86 1.73 Total 5.84 5.73 5.90 5.74 5.05 5.00 5.45 5.06 5.09 5.67 5.07 5.20 By days 11.57 11.64 10.05 10.51 10.76 10.27 By weeks 33.26 31.54 Average 1.39 1.31 * E and L refer respectively to early and late periods of the same day. • Effect upon the Accuracy of Judgment 51 TABLE 23 Short Series Handwriting. Average Deviation Condition: 68f F., 50%, 45 at. ft. no fans 86° P., 80%, no fresh air, no fans 6/9 6/10 6/11 6/15 6/16 6/17 EL E L E L E L E L E L B.R.B. 2.26 1.98 1.65 1.33 1.29 .98 1.38 1.44 .88 1.23 .53 .96 E.M.J. 1.46 1.13 1.34 1.44 1.35 1.01 1.14 .88 .82 1.47 1.62 1.33 J.S. 1.72 1.02 1.46 .64 .67 .94 1.79 1.42 1.57 1.27 .71 .92 J.U. 1.21 .83 .85 1.55 1.03 1.41 1.29 2.12 .87 1.35 1.90 2.03 Total 6.65 4.96 5.30 4.96 4.34 4.34 5.60 5.86 4.14 5.32 4.76 5.24 By days 11.61 10.26 8.68 11.46 9.46 10.00 By weeks 30. 55 30. 92 Average 1.27 1.29 Condition: 65° F. £0%, no fresh air, no fans 86° F. 80%, 45 ca.ft.no fans till 6/23 6/24 6/29 6/30 7/1 E L E L ELELELEL B.R.B. 1.28 1.45 1.26 .88 .89 .65 .78 .69 .89 .60 .99 1.02 E.M.J. 1.40 1.09 1.59 1.78 .79 1.16 1.09 .88 1.20 1.47 1.42 1.31 J.S. 1.16 0.82 .99 .89 1.75 .88 1.36 1.11 1.36 1.06 J.U. 1.60 1.29 1.33 1.71 1.42 1.26 1.29 1.72 1.23 1.10 1.22 2.07 Total 5.44 4.65 5.17 5.26 3.10 3.07 4.914.17 4.68 4.28 4.99 5.46 By days 10.09 10.43 6.17 9.08 8.96 10.45 By weeks 26. 69 28. 49 Average 1.22 1.18 Condition: 75° F., S0%, 45 cu. ft. no fans 86° F., 80% no fresh air, sfans 7/6 7/7 7/8 7/13 7/14 7/15 ELELELELELEL B.R.B. 1.25 1.52 2.28 .69 .87 1.08 1.22 .58 .95 1.05 .90 .84 E.M.J. 1.16 .78 1.36 .79 .60 .84 1.05 .84 1.03 1.90 .98 2.08 J.S. 1.22 1.05 1.04 1.26 1.34 1.11 1.65 1.16 1.78 1.05 1.26 1.23 J.U. 1.48 1.50 1.46 1.66 1.16 1.61 1.51 1.57 1.51 1.20 1.07 1.07 Total 5.114.85 6.14 4.40 3.97 4.64 5.43 4.15 5.27 5.20 4.215.22 8.61 9. 58 10.47 9.43 29.48 1.22 By days 9.96 10.54 By weeks 29.11 Average 1.21 52 Ventilation in Relation to Mental Work TABLE 24 Composition. Average Deviation Condition: 68° F., 50%, 4S cu. ft, no fans 86° F., 80%, no fresh air, no fans 6/9 6/10 6/11 6/15 6/16 6/17 ELELELELEL EL B.R.B. 12.4 8.6 14.2 6.7 6.65 6.45 7.35 9.26 9.2 9.25 7.15 6.45 E.M.J. 8.3 10.15 8.4 9.1 8.35 11.55 7.5 6.85 7.4 8.2 7.85 7.45 J.S. 8.7 7.65 7.8 7.25 11.1 7.65 10.7 6.95 9.7 7.1 11.45 7.4 J.U. 7.6 12.05 16.3 13.65 11.2 12.55 14.8 14.45 12.9 16.55 13.7 14.65 Total 37.0 38.45 46.7 36.7 37.3 38.2 40.35 37.51 39.2 41.1 40.15 35.95 By days 75.45 83.4 75.5 77.86 80.3 76.1 By weeks 234. 35 234. 26 Av. per half day 98 98 Condition: 68° P., 50%, no fresh air, no fans 86° F., 80%, 4s cu. ft., no fans 6/22 £ L 6/23 £ L 6/24 £ L 6/29 £ L 6/30 £ L 7/1 £ L B.R.B. 7.95 5.9 E.M.J. 5.7 6.8 J.S. 7.25 5.1 ;.U. 10.15 13.55 9.5 8.75 8.55 6.3 7.8 8.15 14.5 12.95 6.65 6.35 5.25 9.65 9.3 11.75 6.1 6.52 7.6 8.45 7.05 7.95 10.85 8.4 7.95 9.3 8.8 10.05 6.5 5.35 8.85 10.15 7.15 7.5 9.2 8.95 6.55 8.05 14.3 11.85 Total 31.05 31.35 40.3 36.15 21.20 27.75 31.6 31.32 32.1 34.85 37.2 36.35 By days 62.4 76.5 58.95 62.92 66.95 73.55 By weeks 197.85 203.42 Average 8.9 8.5 Condition: 75° F., 50%, 45 cu. ft., no fans 86° F., 80%, no fresh air, no fans 7/6 £ L 7/7 £ L 7/8 £ L 7/13 £ L 7/14 £ L 7/15 £ L B.R.B. 7.95 6.6 E.M.J. 8.95 6.9 J.S. 5.65 8.25 J.U. 9.05 13.85 8.4 8.15 8.2 7.95 6.25 7.35 18.0 12.95 7.35 7.45 8.75 11.0 8.7 5.25 14.65 13.25 6.15 7.31 9.2 14.94 7.5 5.85 20.85 9.9 7.9 7.3 9.05 10.35 6.55 4.7 10.45 12.52 7.05 7.2 7.7 10.75 8.15 7.15 13.25 9.4 Total 31.6 35.6 40.85 36.4 39.45 36.95 43.7 38.0 33.95 34.87 36.15 34.5 By days 67.2 77.25 76.4 81.7 68.82 70.65 By weeks 220.85 221.17 Av. per half day 9.2 9.2 EJffect upon the Accuracy of Judgment 53 The original plan for Experiment III did not contemplate making any use of the time spent in the judgments. Enough time was allotted to enable each person to examine the specimens carefully and to make his judgments as well as his ability allowed, any ten- dencies to relax care and effort being permitted to show themselves. The time spent was, however, recorded, the detailed facts being given in Tables 25, 26, and 27. These tables show, besides the expected general decrease in time spent as the experiment progressed, an apparent tendency for the hot weeks to show a little more time spent than would be expected from their chronological position in the six- weeks series, and for the cool weeks to show a little less. Table 28 and Fig. 8 summarize the facts. The time spent in mak- ing certain judgments of lines of poetry is included. The accuracy of these judgments has not yet been computed.* What the significance is of a greater expenditure of time in such an experiment is not known. It might mean a real need of more time to make as good a judgment, or a stronger impulse to rest be- tween judgments. It might mean a greater punctiliousness, spend- ing more time than was needed. It might mean a change of atti- tude and habit due to matters entirely irrelevant to the conditions of the air in the room. The judgments of comfort taken at the end of the day were as shown in Table 29. It appears, as in Experiment I, that the wet- bulb temperature was the main cause of discomfort, rather than any conditions of the air due to its chemical constitution. It also appears that the comfort vote is in some measure a result of contrast effects. The votes late in the seven-hour period on the hot days report shghtly greater comfort than do the votes early. The reverse is the case for the cool days (this was for June when the room at 68 was, as a rule, cooler than the outside air). The votes imder the hot condition reported slightly greater comfort on the last day of the three than on the first. The reverse is the case for the cool weeks. Also the difference between comfort votes at * While this monograph was in press, the accuracy of one-half of these judgments of poetry was computed. The subjects did a little better on the cool days. They also fell off during the day less on the cool days. The inclusion of this test's results with those of the tests in judging penmanship and composition, balances the slight advantage to the hot days which the latter showed. Giving about equal weight to each of the three and com- bining the average for the hot days differs from that of the cool days by less than one-half of one per cent. 54 Ventilation in Relation to Mental Work TABLE 25 Long Series Handwriting Number of minutes taken by each of four individuals to rate 100 specimens of penmanship 68° F., so% rel. hum., 4S cu. ft. no fans 6/9 6/10 6/11 EL EL EL B. R. B Si 33 18 18 12 08 E.M.J 65 39 40 33 22 14 J. S 56 37 39 37 26 30 J. U 55 38 31 32 21 16 86° F., 8o% rel. hum., no air, no fans 6/15 6/16 6/17 EL EL EL B. R. B 14 19 27 17 16 33 E.M.J 15 24 21 19 15 28 J. S 22 30 23 22 19 36 J. U 29 38 34 36 12 19 (5S° F., 50% rel. hum., no air, no fans dill 6/23 6/24 EL EL EL B. R. B 17 13 10 19 12 14 E. M. J 16 13 14 14 12 19 J. S 15 11 33 24 J. U 11 09 16 16 13 20 86° F., 80% rel. hum., 4s cu. fl. no fans 6/29 6/30 7/1 EL EL EL B. R. B 13 10 08 22 20 24 E. M. J 15 13 13 13 12 12 J. S 14 12 13 10 17 26 J. U 12 12 22 13 17 10 7S° P-t 50% rel. hum., 4s cu. ft. no fans 7/6 7/7 7/8 EL EL EL B. R. B 12 13 12 12 21 21 E. M. J 13 16 15 13 21 18 J. S 12 29 14 29 18 22 J. U 16 15 11 12 16 15 86° F., 80% rel. hum., no air, 5 fans 7/13 7/14 7/15 EL EL EL B. R. B 29 27 21 21 13 26 E.M.J 21 20 23 21 16 26 J. S 31 17 46 20 16 26 J. U 34 40 30 19 15 10 Effect upon the Accuracy of Judgment 55 TABLE 26 Short Series Handwriting Number of minutes taken by each of four individuals to rate 10 specimens of penmanship" (55° F., 50% rel. hum., 45 cu. ft. no Jans 6/9 6/10 6/11 EL EL EL B. R. B 08 OS 04 OS 03 03 E.M.J 05 12 07 09 04 03 J. S OS 05 09 08 05 04 J. U OS 06 05 05 04 03 86° F., 80% rel. hum., no air, no fans 6/15 6/16 6/17 EL EL EL B. R. B 02 04 01 06 02 02 E. M. J 03 04 03 06 07 04 J. S OS 04 03 03 03 OS J. U OS 03 02 02 04 02 6S' F., 50% rel. hum., no air, no fans 6/22 6/23 6/24 EL EL EL B. R. B 03 01 04 06 04 04 E. M. J 05 03 09 03 04 04 J. S 05 03 02 03 J. U 02 03 02 02 02 02 86° F., 80% rel. hum., 4s cu. ft. no fans 6/29 6/30 7/1 EL EL EL B. R. B 02 02 02 01 03 03 E. M. J 03 03 03 02 02 02 J. S 03 03 03 01 03 03 J. U 02 03 03 11 03 03 75" F., 50% rel. hum., 4S cu. ft. no fans 7/6 7/7 7/8 EL EL EL B. R. B 02 02 03 03 08 03 E. M. J 03 03 02 02 02 01 J S 06 03 04 03 02 01 J. U 04 02 02 02 02 02 86° F., 80% rel. hum,, no air, 5 fans 7/13 7/14 7/15 EL EL EL B. R. B 01 01 01 01 01 01 E M J 02 03 03 02 02 02 IS ... 03 02 02 01 01 01 J U 02 04 03 02 02 01 56 Ventilation in Relation to Mental Work TABLE 27 Composition Number of minutes taken by each of four individuals to rate 20 specimens of composition 68° F., 50% rel. hum., 45 cu. ft. no fans 6/9 6/10 6/11 EL EL EL B. R. B 38 25 37 31 18 23 E. M. J 26 20 27 23 10 16 J. S 25 22 27 25 22 IS J. U 65 20 23 17 19 20 86° P., 80% rel. hum., no air, no fans 6/15 6/16 6/17 EL EL EL B. R. B 11 13 14 16 13 13 E. M. J 22 19 13 14 14 21 J. S 23 18 19 23 20 31 J. U 22 21 20 19 16 27 68° P., 50% rel. hum., no air, no fans 6/22 6/23 6/24 EL EL EL B. R. B IS 16 15 20 18 18 E.M.J IS 16 12 11 IS 14 J. S 19 14 19 18 J. U 11 10 12 13 12 14 86° P., 80% rel. hum., 45 cu. ft. no fans 6/29 6/30 . 7/1 EL EL EL B. R. B 11 13 14 10 12 28 E. M. J 11 10 09 07 10 09 J. S 08 09 13 26 16 19 J. U 11 14 IS 13 18 12 75° P., 50% rel. hum., 45 cu.ft. no fans 7/6 7/7 7/8 EL EL EL B. R. B 12 13 11 11 07 08 E. M. J 07 09 05 04 07 09 J. S 06 IS 06 12 08 10 J. U 09 08 08 07 09 08 86° P., 80% rel. hum.., no air, 5 fans 7/13 7/14 7/15 EL EL EL B. R. B 13 13 10 13 11 09 E. M. J 08 06 08 06 07 05 J-S 13 12 15 08 07 07 J. U 12 08 12 12 06 05 Effect upon the Accuracy of Judgment 57 yo HQ JO 10 \S u r^ 10 rJI nj- 1. Fig. 8. Average Number of Minutes Spent in Examining and Judging in Each Period under each Condition of the Air. The vertical dash-Unes mark the divisions between the weeks, the base-line representing the six weeks of the experiment in chronological order. 58 Ventilation in Relation to Mental Work TABLE 28 Total Time Spent by Four Subjects in Examining and Judging Speci- mens OF Handwriting, Composition, and Poetry 68° F., So% rel. hum., 4$ cu. ft., no fans 6/9 6/10 6/11 First 3 Last 3 n L EL EL 533 397 401 360 288 266 1331 914 5(5° F., 8o% rel. hum., no air, no fans 6/15 6/16 6/17 EL EL EL 283 311 278 289 208 316 872 813 68° F., So% rel. hum., no air, no fans 6/22 6/23 6/24 EL EL EL 206 180 220 213 205 223 606 641 56° F., 8o% rel. hum., 45 cu. ft., no fans 6/29 6/30 7/1 EL EL EL 162 167 186 197 207 219 515 623 75° F., 50% rel. hum., 4S cu. ft., no fans 7/6 7/7 7/8 EL EL EL 157 197 139 183 179 171 493 533 86° F., 80% rel. hum., no air, 5 fans 7/13 7/14 7/15 EL EL EL 210 204 227 167 154 166 641 487 TABLE 29 Comfort Judgments Condition: .o> ^0"= >.„.^ "«" U OcDiNtP e^ OtOOO ^o^-eOoOOO ^q 00-^Mt* O ^ ^ OOCqoOO S -"fONO —.00 •!:' OOOr^-* So WrtiO^ J (!< « -*Ttioo CM oootoo ►? ft" a wcofN-* .- oonw ^ • COCOWCQ f-H^ P> . ■^WCON CO'^iO ex ^ ._ C -; C1OCCOO »0 r-i.-iiOM O • NCOCOCO CO 2 J ■* ^" MCO-^iO >4 § .a -"UNOOOO § 0000 ffi § s NOOCO § OfflUNO 00 ^ ttI ''^ -: D^ uJ « O-<#M00 uJ OOCOO > fcJ « Tf^t-ClCO tJ "5 «Mt^« S s oot^ooco S ■*ai H S * rHO-*Tt( S cootoscd «i > 5 '^^^ -'CDNOOO 0000 !^r^ ^lOOCOtO ^ffiCOOO , M S (Ni>(D« Tti kJ Q * ©oo-^ t^i>-«*o S tn "^HMOOto oiNooo >:^5 '^M'^^ON *^m^N^ 5- tn * -^NcoN oco r1 hIh "* «oeococo i-h^ojos S Cd • Mi-iMW i-tCO W • COrHCOCO NNm« U 5 > Oh en W o Q Pi ^ S ■^N«0 0000 n U 2 MOOeD «M«iO y S N5O00O) 00000 ^ S t^cocoeo lotouj*-! • .- P . ^i>cooi „ »ot- -• O co©or^ cocoooo O 12 S OtJI^OO ^ OOONO f-H ^ "^"^BOCOOOi "^ "^ o-*>oo O ^OI>C0 — Jv OO'HOOJ "^ ONOOO y .* A (N(N^^SN0I>0 ^"2^M»HU5 iJ o" OOOOCO . 010 P6 O COCOOiO h; COOJ'H^ t> 00 ^ ,-(,-i^.-i o W fe "^ ■< COC<)MN "^ i-HiHCOCO ^Z . " S So" . & J S S 00000 ".rj ONOO >' ® S OOOSt^ ^ lO-^OO >3 s nt)I!oo ooo« ^ s mrooioi « tocc-^o ^'^ "^ i-rf^ nn ^"\ ^U J*^ /^ ■«4J 1^ 1^^ /^\ /^1 Ik^ i-J^ < _>_ ' OOCOO^ t* O-^iOiD 01(Nh-Q3 - " ■ ■ ■ 1-1 M CO "caeo-^oo h-«)<*o fl 3 m-*»oo •-H-o eoeoeoco eo««'* w^ cocococo 72 Ventilation in Relation to Mental Work ■* . WrHNrH 00 « M r-l W N „- -1 CqrtNrH „- «(Mr-l S < to . t- a . ^ a OWlHOl iJ »»rHrH ^ S « O tO OO ^-S! ►^ .jk" »n Z .to M to to O ■« a t-MSffl " ffiOrtO 3 6 S •*o<0S ^ '5ES5S S 5S5-1 nto«m n oa . oiixooi ^ oior^ ' rt p; N rnrH o- u5 « N ^ „ 00 »< -• « -' H ' rt p; N rnrH o- u5 « N ^ W O. rH 00 (N ,5 "^ "O a lOtOOO tj "" r4«rtC5 k„ g .4 (Mi-iCOrH '=* NNrt 2 " . ?3 Q a OMNW "^ !g02 . t^t^cOt^ U500-* ~ < . -* ^ i Hi* « a oif-OOffl "" ,-it»lOl0 fi "> ^ OOOTfoO '° ow* § $ ^?322^ ««- g g ^ "■' a SSSS mi^rt« 00 5 : ioio-*» N>o^- m ° j» so w £ S 8 § „ ^ ?5'°S2 S - "S?3S WH ^b;™«"= ^«»* 7^1 3 ^^ • t.0JMM ^ «0>tO® o * (NtS-*0 fflO-* Ph S ^« -^ S «N'^ CL, 6S "^ 6? o^ e^ i:S» 5 Q o _jo fc ^ IN05NO TfNlog S "" ® 00050 "5 (OOOOO 3 OOS"jO COIOOSO O .' ■ ©to ■* . OSW"3 ^ "^ J lOt^OOOO '° ONtOg "^ if ^ ■*OON «" 0000-* a ooomrt ■*-*S2 2 to J i^mco-* to rtoo p* a OTOmffl cCNcoa y -^ . r-ieci-tco -j* -^Nco O ^ .■ "-I '-' OS l^"^ J Kl N * Bh U3 H h ?; ^-^ SS-^ a to . -< 2 S «■ MOtHOS O "^ Ot-aS fl S NONtO * NOW C "3 a OOOSMOO "5 ^rHOsCS jJ . c^co OOtON a ® 1^ 5 a ooN^t^ y «T-«0 ■iO(N(N t^ ^ j; Oco-^b- . weONCo « -' e z. S en . CO "SfMN - oooo a: I— I < XI Q > w S .. is to o U u -" S CQ Q s « H O & Q O e« □0 ® *J MtooeD a OiOOCOIV J 1Hoo^•cD . ocoeoco S OCONOO to h CI Ti< h H01>O . CQCOCliN lOCDCO -. OWOO o MOO H a o S »• MiHCOiH NiOOiH *" OTt > n >-! m X > H Q Pi a w £; w y .. & o "^ ^ iz; W ° 3 g m o < 5 H g Oh H O Q O PL, COOb- a iHccooto i-HiOWO) a OOOIMO rH coeoo iHCOCOOJ J «r-liH S ©NOW OCOCOQO -• MiHf-1 o < »0(NO r» 1-1 ." ^-1 iH rt 'I* 1 « 1 74 Ventilation in Relation to Mental Work TABLE 41. SUMMARY OF RESULTS OF EXPERIMENTS VI, VIII AND XIV Experiment VI : Section I : Half-Day Condition Change 68° 50% Stagnant— 75° 50% Stagnant Addition (Maximal) 60.3 57.9 Mental Multiplication (Option) 85. 8 80. S Typewriting (Option) 324.3 215.7 Comfort 3.7 4.2 Experiment VI: Section II: Three-Day Condition Change Addition (Maximal) 76.2 78.8 Mental Multiplication (Option) 51.1 87.4 Typewriting (Option) 371. 9 450. 3 Comfort , 3.7 3.6 Experiment VIII: Section I: Half-Day Condition Change Addition (Maximal) 68. 6 67. 8 Mental Multiplication (Option) 200. 8 212. 7 Typewriting (Option) 189. 4 169. 5 Comfort 4.3 4.0 Experiment VIII: Section II: Three-Day Condition Change Addition (Maximal) 75.8 72.5 Mental Multiplication (Option) 183. 2 190. 5 Typewriting (Option) 330. 9 304. Comfort 4.9 4.9 Experiment XIV: Section I: Half-Day Condition Change 68° 50% 30 cu. ft.— 75° 50% 30 cu. ft. Cancellation 2 (Maximal) 131.6 13271 Cancellation 3 (Maximal) 147.6 148.9 Mental Multiplication (Option) 147. 7 139. 6 Addition (Option) 154. 155. 5 Typewriting (Option) 289.5 267.3 Comfort and Temperature vote 4. 8 — 28. 1 4. 6 — 34. 3 Experiment XIV: Section II: Three-Day Condition Change Cancellation 2 (Maximal) 133.2 138.1 Cancellation 3 (Maximal) 147.5 145.6 Mental Multiplication (Option) 52. 6 64. 5 Addition (Option) 123. 1 123. 3 Typewriting (Option) 302. 9 306. Comfort and Temperature vote 4. 6— 28. 5 4. 7— 37. 3 SUMMARY AND INTERPRETATION By E. L. THORNDIKE With the forms of work and lengths of period used, we find that when an individual is urged to do his best he does as much, and does it as well, and improves as rapidly, in a hot, himiid, stale, and stag- nant air condition (86° F., 80% relative humidity, with no air or only recirculated air, and with no movement of the air save what is caused by events in the room and, in the case of recirculation, by the recircu- lating force) as in a optimum condition (68° F, 50% rel. himi., 45 cu. ft. per person per minute of outside air introduced). This restilt was obtained when the individuals were subjected to the bad conditions 4 hours a day for five consecutive days. Enough individuals were tested to make the result entirely reliable. The same negative result has been obtained when the individuals were subjected to temperatures of 75° and 68° each for three suc- cessive days of 7 hours each. Experiments subjecting individuals to the contrasted conditions for longer times (say, for sixty working days of 8 hours each or a half-year of school days of five hours each) are desirable. It is hoped that the importance of the results just mentioned will lead someone who has the facOities, to make such experiments. The hot conditions cause a relative rise in body temperature and quickening of the pulse as well as the various annojdng sensory conditions due to the heat and perspiration. These may have an effect when con- tinued week after week that they do not display over a short period. We find further that when an individual is given work to do that is of no interest or value to him and is deprived even of means of telling how well he does do it, and is in other ways tempted to relax standards and do work of a poor quality, he stUl shows no inferiority in the quality of the product produced in stagnant air at 86°, 80% r. h., with 30 to 40 parts of CO2 per 10,000, he being subjected to this condition for 8 hours a day for four successive days, and tested on the second, third, and fourth day. There is some evidence that he spends more time on the work, but even this is not certain. 75 76 Ventilation in Relation to Mental Work Finally, we find that when an individual is left to his (or her) own choice as to whether he shall do mental work or read stories, rest, talk, or sleep, he does as much work per hour when the temperature is 75° as when it is 68°. In the experiments on this topic, tempera- ture alone was varied, other air conditions being kept constant. The reason for this limitation was the apparent absence in all the experi- ments to date, of any physiological effects due to staleness of the air as shown by high COj content. The smaller difference was chosen to make the experiments suitable for their main pxupose as a test of certain conditions upon appetite, the psychological tests being in this case secondary. It is also the case that the effect of moderate over-heating upon the inclination to do mental work is, in practice, more important than the effect of extreme heat. The two condi- tions (68° and 75°) were maintained each for three successive days of seven hours each. In a very short experiment wherein the temperature was varied to 86° F., 80% rel. hum., there did seem to be a dimiaished incUnation to do mental work, but the variability of results in all such experi- ments with optional work advises us to postpone any conclusion concerning the effect of very high temperatures upon incUnation until adequate experiments are made. These results are obviously in sharp contrast to the expectations from the ordinary discussions of ventilation in text-books and the like. The conmion view used to be that air was "good" as in the open country and "bad" as in a sealed, crowded room; and that bad air was bad for the body and miad as a whole, A less mystical view has been that hot and stagnant air is inevitably enervating and depressing to the mind, causing thought and action to be less rapid, accurate, and suitable to their ends. The former view need not be discussed here imtil its advocates produce some evidence of the fit- ness of good air as a condition of effective thought beyond the fra- grance of the air and their enjoyment of it. If their own logic is a fair specimen of the thinking to which "pure" air predisposes man, we may perhaps prefer the defiled mixture of libraries and labora- tories! The second view seems to be supported by many experi- ences of daily life and it is perhaps desirable to make certain sugges- tions concerning the reconciliation of our experimental results and these experiences. The first concerns the difference between the presence and strength of certain connections or lines of little resistance for conduction in Summary and Interpretation 77 the brain, and the excitability or readiness of these connections to conduct. There seems to be such a difference, though the detailed physiology of it is hypothetical. Long repeated conduction over a connection seems to strengthen the connection but make it less ready to act. Rest seems to weaken a connection but makes it more ready to act. Certain diseases seem to reduce readiness enormously •without much altering the actual strength of the connections. The phenomena of refractory periods seem to require some such double form of action in the nervous system. To outside observation the existence and strength of neural connections is witnessed in mem- ory, thought, and skill. The readiness of conduction units to con- duct is witnessed by interest and satisfyingness of the thinking or action. It is, of comse, hard to distinguish between the satisfying- ness or intolerability of the thinking or action itself and that of the accompanying conditions, but experimental analysis can probably generally decide correctly. When a person does less mental work or does the work less well in hot, stale, stagnant air, the cause might be (1) that the strength of the neural connections by whose action mental products are pro- duced was weakened; or (2) that, their strength being unimpaired, they were, by changes within themselves, less ready to act; or (3) that, though no intrinsic change in them had occurred, the person re- sponded to the discomforts of a hot skin, flushed face, sticky body and the like, by relaxing or intermitting mental work. In the first case, the person could not think or act as well in bad as in good air if he would. In the second case, he could think as well, but would gain in comfort if he relaxed or intermitted the imsatisf)dng activity, more in bad air and less in good air. In the third case he could think as well, and would be no less comfortable if he did maintain mental activity as much in bad air as in good air. The bad conditions of the air tested in our experiments did not seem to reduce the strength of neural connections at all. Nor can I see any reason why they should. The brain does not get enough hotter in a room at 86° 80% to lead us to expect any considerable disturbance in associative strength. Nor did the bad conditions seem to alter the intrinsic readiness to conduct of the conduction imits involved in adding, multiplying, and the other functions tested. Had they done so, the subjects in the experiment with judgments should have responded to the bad conditions by a relative relaxa- tion of the care with which they examined specimens and rated them. 78 Ventilation in Relation to Mental Work What the hot conditions demonstrably did do was to make the subjects feel uncomfortable. The positive effect on their reports of how well they felt is in striking contrast to the zero effect on how well they did. In ordinary life, they might have sought relief from the hot stickiness of the 86° 80% condition by relaxing the mental work, leaving part of it to be done when it was cooler; or might have omitted the work altogether by the plea that it was too hot to work. But they might thereby have gained nothing if in the end the work had been some time done. On the contrary they might have gained in enjoyment by using the hot periods for mental work and cooler periods for recreation. It may be, that is, that the custom of relaxing or intermitting mental work in response to hot skin, flushed face, perspiring body, and the like gives no evidence that mental work is any more taxing or injurious then than at cooler periods. The higher body-temper- ature, quicker pulse, and sensory discomforts probably are taxing, but we lack evidence that their presence makes the same mental productivity different in its natiure or consequences from what it is in cool air. The discomforts to which men have responded by ceasing mental work might perhaps better be responded to by work- ing to pay for an electric fan, taking cool baths, or thinking out ways to reduce the physical exertions which accentuate the discomforts. Merely to postpone useful thought to a cooler period may leave the net total of discomfort unchanged or even increase it. The custom of relaxing mental work in hot temperatures is not then a proof that such relaxation is necessary or wise, nor irreconcilable with our experimental results. Consider now the two special cases of summer heat and crowded rooms. We take vacations in hot rather than in cold weather. Many of us do not demand as much mental work from ourselves, our employees, or our pupils in the hot as in the cold season. Can this be explained without assuming that heat is really depressing, reducing the ability to do mental work or at least reducing the in- trinsic satisfyingness of the work and so, if equal work is done, de- manding greater strain? The dating of vacations for children may be a reUc from a time when they were taken out of school at such time as their services would be of use; and the dating of vacations for adults seems to depend upon the superiority of the summer for play as well as its inferiority for work; and to depend upon the value of release from Summary and Interpretation 79 the general discomforts of heat rather than the value of release from mental work. In any arguments concerning summer heat, also, the debilitating effects of certain diseases then prevalent and of lack of sleep must be considered. The present writer, in view of the experi- ences of the summer schools maintained in connection with our universities and normal schools, is skeptical of the assimaption that summer temperatures of 70° to 85° with their high hxmiidities are, in and of themselves, imfavorable to mental work. Given x units of mental product to be produced in a year and assuming that the opportunities for recreation are equally attractive in all months, it seems possible that the slackening of mental work in the hot months might be of little or no use. After spending time in a crowded room many individuals feel unfit to do mental work. Dullness, mental inertia, sleepiness, and headache are reputed consequences. And these are commonly attributed to the air. They may be due to the air, but we should also scrutinize the other conditions that usually accompany the spending of time in crowded rooms as at parties, theatres, shopping tours, and the Hke. These are late hours, nervous excitement, uncomfortable clothes, and uncomfortable posture in the case of crowded pubUc conveyances. Improper eating is often a secondary comcomitant. Dullness, mental inertia, sleepiness, and headache used to be attributed unquestionably to the chemical constitution of the air breathed in crowded rooms due to its having been breathed before. This orthodox view of the recent past is now discarded as fantastic, the harm being now attributed to the heat and stagnancy of the air as it meets our skins. But conceivably our skins might be as little to blame as our lungs. Until the total situation of the crowded room is analyzed experimentally with due attention to the sensory over-stimulations, the excitement and worry, the social contacts, the indulgence in foods and drinks, the lack of sleep and other nervous strains, the evidence that the air of a crowded room makes man unable or imwiUing to do mental work is incomplete. Moreover, there are some facts which reduce the general prob- ability that the heat of the air is per se the cause of the reported dull- ness, inertia, and sleepiness. Physical exercise outdoors imder the "best" air-conditions makes many persons duller and more inert than does an equal amount of time spent quietly in a hot ill-ventUated room. The heat of crowded rooms is said to make one sleepy, but the same heat during a summer night is said to keep one from sleep. 80 Ventilation in Relation to Mental Work On the whole, then, the experiences of daily life may conceivably be entirely consistent with the absence of any effect of bad air (within the range of temperature and length of continuance of our experi- ments) upon the ability to do mental work, and with the absence of any effect of a 68° to 75° temperature difference upon the readiness to do mental work. When heat reduces mental work it may do so via the general discomforts which it causes rather than by any in- trinsic disability or unreadiness in the process of mental production itself. Our experiments, however, need repetition and extension. In particular the effects upon mental efficiency of slight elevations of body temperature (from }4 to 1% degrees Fahrenheit) and of per- spiration need to be studied. The experiences of daily life need to be analyzed into their elements, and the separate effect of each ele- ment determined. It will be understood that the remote effects of hot, humid, stag- nant air upon mental efficiency — as by producing susceptibility to disease, by depriving the body of exercise, or by fostering bad habits of diet or sleep, are not considered in this monograph. They are beyond the scope of our experiments. It should also be remembered that our experiments and the entire argument so far concerns only short exposures mostly of from four or eight hours continued daily for from three to five days. It should finally be noted that the problem of odor and its influences upon mental work has also been left outside the range of our experiments. Whether the odor in closed rooms is simply offensive to certain refined ideals or is essen- tially injurious to mental achievement, we have made no effort to decide. We can only say that such odors as were caused under the experimental conditions used did not apparently decrease either the ability or the willingness to do mental work. APPENDIX Following are instructions given to the subjects of the experiments in the preliminary practice and for their direction during the tests. Color-Naming The subject will be provided with a color blank. The object of the experi- ment is to name each color as rapidly as possible. Care must be taken that the subject starts with the sheet in the right position. This position will be shown on each occasion by the experimenter. The procedure will be as follows: The sheet should be laid face downwards; at the given signal the paper must be reversed, so as to reveal the colors. These should be named in succession as quickly as possible, reading from left to right. In case of any misnaming of a color, the subject will be stopped, and made to go back to the point at which the mistake arose. The time taken to name the complete series will be measured, the object is to make this time a minimum. Cancellation The subject will be provided with a cancellation sheet. In this sheet a certain specified number must be cancelled throughout. The object of the experiment is to omit as few cases of the specified number as possible, and to complete a maximum amount of cancellation in the time allowed. The procedure of the experiment is as follows: After writing your name on the sheet, lay it face downwards. On the signal being given to reverse the sheet, commence to cancel, proceeding with this until the signal to stop is given, at which time work must cease immediately. The method of counting is shown below: 2 (number cancelled correctly), minus 2 (number omitted), minus 3 (num- bers wrongly marked). From this method of measurement, it will be noticed that additional speed can outweigh complete accuracy. The object of the subject is to score the maximum amount under these known conditions. Example. — Suppose that you had to cross off 3 or 5 from the list: 134854720 582340589561233840374901593264936279801642. Opposites The subject will be provided with a list of words of which the opposites must be named, a certain range of choice of opposites being allowed. The procedure is as follows: The paper should be laid face downwards and re- versed at the given signal. Opposites should then be given to each word in the first column, and when this column is completed, to those in the second column. At any time when more than 15 seconds is taken for any particular opposite, the subject will be told what the opposite is. The object of the experiment is to complete the list in the minimum time. Examples: good bad rich poor high low roughly smoothly 81 82 Ventilation in Relation to Mental Work Addition You will be given a, sheet containing columns of one-place numbers like those shown below: 8 6 9 5 5 7 6 9 5 4 6 7 9 2 3 2 3 5 5 7 3 4 5 8 8 9 9 6 4 2 This will be placed before you bottom side up. When the experimenter says "Go," you will turn the sheet over and add, writing the sum of each column of 10 figures as fast as you can but without making errors. If an answer is wrong, you will receive no credit for that column. When you finish the examples on one sheet take another. Instructions for Work in the Mental Multiplication of a Three-place Number by a Three-place Number. Used in Experiments I, II, VI and VIII The work is to be done mentally, nothing being written down until the entire product is obtained. You may say the numbers, the partial products or anything else to yourself silently but nothing is to be spoken out loud or whis- pered. You will proceed as follows: Suppose the example is 235; you will multiply 235 by 2, remembering 632 meanwhile that the entire multiplier is 632. Having got the 470, fix it mind. Then multiply 235 by 3 and when you get the 705 add it to 470 remembering that 705 counts as 7050 in adding. As soon as you have 7520, fix it in mind, when you can forget all else except the 235 to be multiplied by 6. Hold 7520 in mind while you get 6 times 235, which is 1410. Now you can forget everything else except the 7520 and the 1410 which counts as 141,000 in adding. As soon as you have added and got the 148,520, write it down. Besides doing the work in the manner described above, you are to record the time in hours, minutes and seconds when you begin each example. Should a. rest be allowed between two examples, record the time of finishing the last example. The score is a composite of your speed and your accuracy. It will be the number of examples done, minus %oth of an example for one wrong figure in the answer, %oths. for two wrong figures, %oths for three wrong figures and %oths for four wrong figures and i%oths for five or more wrong figures. It is then necessary to work carefully enough to avoid more than an occasional error in order to make a good score. Practise first at the mental multiplication of a three-place number by a two-place number and when you get so that you make but few mistakes, proceed to the multiplication of a three-place number by a three-place number. Instructions for Work in the Mental Multiplication of a Three-place by a Two-place Number. Used in Experiment XIV The work is to be done mentally, nothing being written down until the entire product is obtained. You may say the numbers, the partial products, or Appendix 83 anything else, to yourself silently. You will proceed as follows: Suppose the example is 235. Multiply 235 by 2. Having got the 470, you will 32 fix it in mind. Then multiply 235 by 3, remembering the 470 and when you get the 705, add it to the 470 remembering that 705 counts as 7050 in adding. As soon as you have the 7520, write down 7520 beneath the example. Besides doing the work in the manner described above, you are to record the time in hours, minutes and seconds, at which you begin each example. In all this work your aim should be to make the best possible score. The score is, of course, a composite of your speed and accuracy, and will be kept as follows: The number of examples done times 10 minus 2 for each wrong figure in each answer. That is, if all the figures in a five-place answer are wrong you get zero credit; if two are wrong, you get three-fifths credit, etc. You should therefore work carefully so as only very rarely to have errors in any answer. Practise with the following examples to get an idea of how rapidly you can work without making more than an occasional error. Score the time separately for each one and note whether you make any errors in each before proceeding to the next. (1) (2) 427 682 53 47 (3) (4) (5) 723 386 965 85 92 38 Score for practice set : Time for No. 1, min, . " " " 2, " . . " " '■ 3, " . . 4, " .. 5, " .. . .sec. . . . Wrong figures in answer . . Typewriting Instruction Sheet If you do not already know how to use the typewriter keys, shift-key, spacer, and so on, ask to be shown. The score in typewriting will be the number of lines that you can copy, with one tenth of a line taken off for each wrong letter or wrong space. If you make a mistake, do not go back to correct it, but continue copying. Instructions for Grading Specimens of Handwriting Look at each specimen. Give it a grade 4, 4.1, 4.2, 4.3, 4.4, etc., up to 20 20.1, 20.2, 20.3, etc., according to its general merit as handwriting in comparison with the specimens of the Scale. Record the grade you assign-to each speci- men on the record sheet. Pay no attention to the apparent age or training of the person who wrote the specimen nor the apparent speed at which it was written. Grade the specimen itself, disregarding whatever you may think concerning who wrote it, or how it was written. Grade to a first decimal as noted above. Instructions for Grading English Compositions Read through the Hillegas Scale and get an idea of the quality of a composi- tion that has a value of 20, 30, 40, etc. Read each composition and assign to it a mark for general merit in accordance with the Scale. Let general merit mean whatever combination of thought, style and formal correctness you think general merit does involve. Pay no attention to the apparent age or training of the person who wrote the composition. Grade the composition itself, disregarding whatever you may think concerning who wrote it or how it was written. Use 10, 11, 12, 13, etc., up to 97, 98, 99, 100, 101, 102, etc., etc., as grades. Do not try to grade to a decimal fraction nor to the figures on the scale. You must, however, let the scale fix your values in general.