Cop\( z 
 
 EXPERIMENTAL STUDY OF 
 
 MOTOR ABILITIES OF CHILDREN IN 
 
 THE PRIMARY GRADES 
 
 BY 
 BUFORD JENNETTE JOHNSON 
 
 A DISSERTATION 
 
 Submitted to the Board of University Studies of The Johns 
 Hopkins University in Conformity with the Requirements 
 
 for the Degree of Doctor of Philosophy / 
 
 1916 1 
 
 Baltimore 
 
 The Johns Hopkins press 
 
 1917 
 
EXPERIMENTAL STUDY OF 
 
 MOTOR ABILITIES OF CHILDREN IN 
 
 THE PRIMARY GRADES 
 
EXPERIMENTAL STUDY OF 
 
 MOTOR ABILITIES OF CHILDREN IN 
 
 THE PRIMARY GRADES 
 
 BY 
 BUFORD JENNETTE JOHNSON 
 
 A DISSERTATION 
 
 Submitted to the Board of University Studies of The Johns 
 
 Hopkins University in Conformity with the Requirements 
 
 for the Degree of Doctor of Philosophy 
 
 1916 
 
 Baltimore 
 The Johns Hopkins press 
 
 igi7 
 
 (^..^-L.. 
 

 PBE33 OF 
 
 THE NEW Era Printing Company 
 Lancaster pa 
 
 APR 15 1919 
 
CONTENTS 
 
 Page 
 
 Acknowledgments vit 
 
 Introduction 9 
 
 Historical 11 
 
 General Method of Experimental Procedure 16 
 
 Experimental Results: 
 
 Rate of Voluntary Movements 18 
 
 Steadiness of Motor Control 31 
 
 Reaction Times 36 
 
 Accuracy of Movement 41 
 
 Preference in Side of Body Used 53 
 
 General Summary and Conclusions 56 
 
 Bibliography 60 
 
ACKNOWLEDGMENTS 
 
 The writer is under heavy obligations to many who have 
 materially aided her in this work. She is especially in- 
 debted to Dr. Knight Dunlap, Professor of Experimental 
 Psychology at The Johns Hopkins University, who devised 
 apparatus and gave suggestions and criticisms throughout 
 the work; to Dr. E. F. Buchner, Professor of Education 
 at The Johns Hopkins University, for valuable assistance 
 in arranging for the carrying on of the work in the schools ; 
 to the principals and teachers of the schools visited for their 
 co-operation. 
 
EXPERIMENTAL STUDY OF MOTOR ABILITIES 
 OF CHILDREN IN THE PRIMARY GRADES 
 
 I. INTRODUCTION 
 
 The careful study of motions made by adults in the in- 
 dustrial vocations has served to give a scientific basis for 
 almost revolutionary policies and methods in the economic 
 world. The popular question of vocational guidance in- 
 volves various tests of motor ability and control. 
 
 The more important investigations of motor abilities and 
 of learning processes have concerned adult activities. In- 
 quiries including tests of adolescents and of school children 
 in the elementary grades have usually been limited to the 
 single test or to a few repetitions. For a study of indi- 
 vidual variation in meeting new situations, as indicative of 
 previous experience, or for detecting extremes in the normal 
 range of distribution, the single test is most valuable. For 
 the larger number in the middle range, it is generally agreed 
 that special practice makes a measurement of a process a 
 far truer one. 
 
 Because of their attitude to the novelty of the experi- 
 ment, with young children it is almost impossible to ob- 
 tain results from single tests that will give any positive 
 indication of actual motor abilities. The tendency to over- 
 estimate the value of results obtained from particular ex- 
 periments becomes dangerous when these results are uni- 
 versally applied and used to justify some procedure, such 
 as for diagnostic purposes in vocational guidance. 
 
 The problem of this investigation is the determination 
 of motor abilities of children between the ages of four and 
 ten years, dealing specifically with the improvement by 
 practice in motor-coordination and the effect upon the 
 
 9 
 
lO MOTOR ABILITIES OF CHILDREN 
 
 learning process of different intervals between practice 
 periods. Rate and precision of voluntary movement, meas- 
 urement of involuntary movement, simple and discriminative 
 reaction times are treated. Sex dififerences, fatigue effects, 
 and preference in hand used are also studied. 
 
II. HISTORICAL SKETCH 
 
 There is no scarcity of data as to tests of the kind under- 
 taken, but varying technique and purposes have given a 
 preponderance of unconfirmed experimental results. 
 
 I. Speed of Movement 
 
 (i) Practice Effects. 
 
 Results of the tapping test used with adults in practice 
 series by HoUingworth (ii)/ Wells (21), Marsh (16), 
 and Dresslar (7), show improvement due to practice, vary- 
 ing in rate and amount with individuals, conditions, and 
 duration of experiment. The rate is not uniform, Wells 
 (21) reporting that the curve fluctuates more after a week 
 than at the beginning. HoUingworth (11) concludes that 
 there is very low correlation of first trial with final capacity. 
 All previous investigators show that rate increases with 
 age, with some evidence of retardation at periods of retarded 
 physical growth. No prolonged experimental work has 
 been done with children so far as the writer knows. 
 (2) Sex Differences. 
 
 Brj-an (5) found that in single tests on children from 
 five to sixteen years old boys were slightly superior, except 
 at thirteen when the girls excelled. This latter finding, as 
 was suggested in his paper, might be explained by the 
 earlier maturity of the girls. 
 
 Bolton (4) studied rapidity of movement in groups 
 selected according to social status. Tapping with finger 
 on key was form of test used. Five trials with each hand, 
 duration of each trial 5 seconds, constituted an experiment. 
 Records of one experiment for thirty of each sex, eight to 
 nine years old, belonging to a superior social group, were 
 
 1 The numbers in parentheses refer to the list of references given 
 in the Bibliography. 
 
 II 
 
12 MOTOR ABILITIES OF CHILDREN 
 
 compared with those for the same number of inferior 
 social standing. He concludes that "girls are uniformly 
 better than the boys. The girls in the good class do not 
 show greater or even quite as much superiority over the 
 boys of the same class, as the girls of the poor class show 
 over the boys of the same class." 
 
 Gilbert (8) gave single tests with right hand to one 
 hundred children of each age, fifty of each sex, from six 
 to seventeen years old. Rapidity was measured by tapping 
 on telegraph key in connection with chronoscope for forty- 
 five seconds. Records were taken only of first five and 
 last five seconds. He found that boys excel in speed. He 
 gave similar tests to Iowa school children. Results there 
 showed a slight superiority for girls during the earlier 
 years. 
 
 For ages twelve and a half to thirteen and a half years 
 Burt and Moore (6) found that 69.8% of boys exceeded 
 median speed of girls. Among adults, Thompson (20) 
 found that 88% of men tested exceeded the median speed 
 of women. 
 
 (3) Fatigue Effects. 
 
 Wells (21) found among adults that practice brings 
 warming up, showing in increased immunity to fatigue, and 
 that initial rate and fatigue loss are negatively correlated. 
 
 Dresslar (7) reports that with subject working at "limit 
 of practice" sensations of fatigue ceased, but objective 
 phase persisted. 
 
 Gilbert (8) found that susceptibility to fatigue decreases 
 uniformly for both sexes with increase in age; that boys 
 tire more quickly than girls, but their initial superiority was 
 sufficient to over-balance the greater percentage of fatigue 
 loss and make their net efficiency greater. Among the 
 Iowa children he found practically no difference between 
 sexes in fatigue loss during last five years, from twelve to 
 seventeen. 
 
 (4) Index of Right-handedness. 
 
 Wells (21) reports for adults no greater improvement by 
 
HISTORICAL SKETCH I3 
 
 practice with left hand than right hand, but that right hand 
 tends to warm up more than left hand ; hence is more 
 immune to fatigue. He finds the relationship between right 
 and left hand more variable in women than in men and their 
 hands farther apart in ability. These conclusions are based 
 upon only two experiments, in first of which women sur- 
 passed men with right hand but elsewhere were inferior. 
 
 Woolley and Fischer (23) found superiority in tapping 
 test more reliable an indication of left-handedness than 
 superior steadiness or strength. 
 
 Bolton (4) found no significant diflference between right 
 and left hand for "good" and "poor" subjects. 
 
 2. Involuntary Movement. 
 
 (i) Practice Effects. 
 
 It is generally recognized that there is little improvement 
 by practice in steadiness test, unless by a trick in method 
 for control of respiration. Since control of muscles to 
 prevent moving of body, co-operation of subject, and phys- 
 iological processes affect results so greatly, satisfactory 
 control, especially for children, is difficult to establish. For 
 children of the age considered various forms of tests have 
 been used and for varying purposes. No data actually com- 
 parable is available, so far as writer is aware. 
 
 Hancock (10) concludes from use of ataxiagraph that 
 adults have 5.8 times the control of children from five to 
 seven years old. 
 (2) Sex Differences. 
 
 Distinct sex differences are not evident. McDonald 
 (15) and Hancock (10) found girls steadier than boys. 
 In tracing test Bryan (5) reports a slight superiority for 
 boys, while Bolton (4) found that girls excel. 
 
 Woolley and Fischer (23) used a form of test similar to 
 ours with seven hundred and fifty-three children fourteen 
 years old, and one year later three hundred and ninety-two 
 boys and two hundred and eighty-seven girls were retested. 
 Their conclusion was that "girls are clearly superior to 
 the boys in steadiness." 
 
14 
 
 MOTOR ABILITIES OF CHILDREN 
 
 (3) Index of Right-handedness. 
 
 Variations are so great in results and a shift in superiority 
 from one hand to another occurs so often that the index of 
 right-handedness is not very rehable. Woolley and Fischer 
 (23) found forty-eight boys and thirty-one girls superior 
 with left hand in first test. Of these, forty-six boys and 
 twenty-nine girls were retested a year later. Only ten 
 boys and five girls remained left-handed, while twenty-five 
 new subjects showed superiority with left hand in second 
 test. 
 
 3. Simple and Discrimination Reaction Times 
 
 Gilbert (8) reports reaction times for children from six 
 to seventeen years old. The median value for ten trials 
 was accounted the measurement of a subject's reaction time. 
 Averages of these values were taken to represent the dif- 
 ferent ages. Discrimination preceded simple reaction. He 
 found boys quicker than girls, except for discrimination re- 
 actions at age of six, and a decrease in reaction time with 
 increase in age. 
 
 4. Accuracy of Movement 
 
 Probing or thrusting movements in aiming have been 
 frequently used for measuring precision, as in Thompson's 
 (20) target test on adults, in which she found better co- 
 ordination on part of men. 
 
 We have not been able to find any prolonged study of 
 children. Bagley (i) studied accuracy in aiming at a 
 target — ^bull's eye, 10 mm. in diameter — from a distance of 
 two meters. The experiment consisted of three trials, ten 
 marbles thrown at a trial. Errors in millimeters as to 
 distance from center were computed. Ages of subjects 
 varied from eight to seventeen years. He reports that 
 "boys slightly surpass the girls in motor ability." There 
 is a gradual increase in ability with increasing age. 
 
historical sketch 1 5 
 
 5. Distribution of Practice Periods in Learning 
 
 Leuba and Hyde (13) made four divisions of subjects in 
 testing progress in writing English prose in German script. 
 The daily and alternate-day practice groups made better 
 records than the twice-per-day or every-third-day groups. 
 
 Lashley (14) found that college boys show greater im- 
 provement in skill in archery for practice periods of five 
 shots per day, than for a greater number of shots. 
 
 Munn (17) carried out a series of ten substitution tests, 
 one test each day, on twelve children of an average age of 
 eight years. Six were taken in the morning, six in the 
 afternoon, and while slower in the beginning, children 
 make greater but more irregular gains than adults. From 
 her records of normal school pupils given varying intervals 
 between practice periods in this test, she concludes that 
 short and frequent practice periods are most valuable. 
 
 Murphy (18) found that normal school girls in practice 
 at javelin throwing made greater gains when given weekly 
 or alternate-day practice than through a distribution of 
 five times per week. 
 
 6. Summary 
 
 y As a summary of the main points in the findings of 
 ' previous investigators we may note : 
 
 That all results show a marked increase of motor con- 
 trol with age. 
 
 That the majority report a slight sex difference in favor 
 of boys in rate and accuracy of movement ; in favor of 
 girls in steadiness. Loss by fatigue is greater for boys and 
 these sex differences are more marked with increasing 
 chronological age. 
 
 That the index of right-handedness varies with age, 
 being more pronounced in childhood. 
 
 That there is disagreement as to the most economical 
 distribution of practice periods in learning, but somewhat 
 stronger evidence in favor of short and frequent periods, 
 with preference given to morning hours for children. 
 
III. PROCEDURE 
 
 The following tests were made by the writer. Similar 
 tests had been given previously both to children and adults 
 and satisfactory methods of control and procedure carefully 
 studied. 
 
 In the first grade of a public school in Thomson, Georgia, 
 where the pupils are of varied social status, such as is 
 found in a small Southern town, eighteen girls and sixteen 
 boys between the ages of five and nine years were given 
 the Steadiness Test on September i6 and 17, 1915. The 
 following Monday at the same hours, from 9 to 12 o'clock, 
 a series of tests in tapping were begun and continued 
 through three weeks, omitting Saturdays and Sundays. 
 The Monday following the completion of this practice series 
 in tapping a second steadiness test was given. Detailed 
 methods and apparatus are described under the special 
 headings for each form of test. 
 
 The measurement of simple and discriminative reaction 
 times was made in The Johns Hopkins Psychological Lab- 
 oratory. The difficulties in arranging for many children 
 to work there caused the number of subjects to be small 
 and the distribution such that sex differentiation could not 
 be of much value. The study of the factors entering into 
 this test upon young children has been highly profitable. 
 
 The tests in precision of movement as measured by aim- 
 ing at the center of a system of concentric circles were made 
 upon children of the first and second grades of a public 
 school in Baltimore. Only normal children, free from 
 physical defects as determined by medical inspection, were 
 tested. They came from the poorer district of the city 
 and in many cases of foreign parentage. These children 
 were always eager to take part in the "game." Groups of 
 
 16 
 
PROCEDXJSE I 7 
 
 twelve, six boys and six girls, were selected for different 
 practice periods, varying from five days successively in one 
 week to once in two weeks. Tests were begun November 
 29, 1915, and continued until middle of April, 1916. 
 
 Further details of experimental procedure are discussed 
 later in connection with results of various forms of tests. 
 
IV. RATE OF VOLUNTARY MOVEMENTS 
 
 I. Apparatus 
 
 The tapping test similar to that described in Whipple's 
 (24) Manual was used for testing quickness of movement. 
 The board is a brass plate four inches square. The stylus, 
 weighing 19 grams, had a metal needle ]/& of an inch in 
 diameter, 1%. inches long, with a wooden handle 4 inches 
 long, }i of an inch in diameter. Board, stylus, and Ewald 
 Chronoscope were so wired with battery that contact of 
 stylus with plate recorded a tap. By stop-watch, number 
 of seconds required for one hundred taps was scored. 
 Time required for first fifty taps was also noted to secure 
 an index of fatigue. Kymograph record was not made, but 
 rate of children is such the experimenter could count taps 
 and thus kept check on record of chronoscope. This 
 method is open to criticism as a source of error, but the 
 personal equation was the same in each case and the differ- 
 ences too small for significant errors. 
 
 2. Method of Conducting Test 
 
 The board was placed upon a table near the edge and 
 each child stood during test. In taking position some had 
 a tendency to rest free hand upon table but this was not 
 permitted. Blocks were used to adjust position of board 
 for each individual, so that a comfortable position was 
 maintained. Freedom was allowed in use of movement, 
 resulting in combination of wrist and elbow. Each child 
 was shown how the taps caused the hand to move on the 
 "clock," but this was screened from sight during tapping. 
 A few preliminary taps were given him in this explanation. 
 He was told to tap just as rapidly as possible from the 
 signal " Ready Now " to that of " Stop." Right hand was 
 tested first. After a rest of thirty seconds, left hand was 
 tested. 
 
 18 
 
RATE OF VOLUNTARY MOVEMENTS IQ 
 
 A room adjoining the Assembly Hall, very quiet during 
 the hours of experimentation, was available for all the 
 tests. Two children were taken at a time. One sat across 
 the room from the table and there was no talking or moving 
 about during the tapping. Throughout the entire series 
 the children seemed ready and eager to tap, except for the 
 desire to stop at the onset of fatigue. This desire was 
 but poorly controlled by a few with their left hands. 
 
 3. Subjects 
 
 All the pupils from one First Grade room, between the 
 ages of five to nine years, began the test, — nineteen girls 
 and eleven boys. There were four girls and three boys of 
 the higher section, who had been in school the Spring 
 before. The others had just entered the first week in 
 September. Only nine girls and four boys were present 
 each day of the fifteen days on which tests were made. 
 There are thirteen girls and six boys whose records are 
 reported, their absences ranging only from one to two days. 
 Height, standing and with shoes, weight, and age of each 
 subject were recorded. In physical measurements they ap- 
 proximate closely the norms in stature and weight estab- 
 lished by Boas (3) and Smedley (19). The girls averaged 
 six years, eight months, twenty-nine and two-thirteenths 
 days in age, ranging from five years, ten months, fourteen 
 days to seven years, eight months, sixteen days. The boys 
 averageid six years, eight months, twenty-six and two- 
 thirds days, ranging from six years to seven years, one 
 month and twenty-eight days. There is a diflference of 
 2.48 days in averaged ages, while the range is six months 
 greater for girls. 
 
 4. Computation of Results 
 
 The daily averages of time in seconds required for first 
 fifty and second fifty taps with each hand were computed 
 for both sexes. The learning curves are plotted from 
 averages for the complete test, one hundred taps. 
 
20 MOTOR ABILITIES OF CHILDREN 
 
 The individual averages for entire series were computed. 
 With these as measurements the averages and mean varia- 
 tions for sex dififerentiation were made. In other words, 
 the average of individual averages was used as measure of 
 group. Median value was also found and probable error^ 
 obtained for determining significance of averages. 
 
 The difference in daily averages of time required for first 
 and second fifty taps was used to indicate loss by fatigue. 
 
 5. Results 
 
 The table below shows the daily averages. T is total 
 time for one hundred taps. D is difference in time for 
 first and second fifty taps, 
 (i) Practice Effects. 
 
 It is clearly shown that there is marked improvement 
 with practice. During the first six days a great percentage 
 of the entire gain is made. For the next five days there are 
 irregularities and the downward tendency of curves for 
 the last three days indicates that a somewhat higher final 
 level of efficiency would have been attained through further 
 practice. 
 
 The average rate from all trials is not attained until the 
 sixth day for girls, the fifth day for boys. The initial 
 records of girls for one hundred taps ranged from 22 to 45 
 seconds with right hand ; 25 to 55 seconds with left hand. 
 For boys, 26 to 39 seconds, right hand; 34 to 38 seconds, 
 left hand. The group of girls had two subjects at each 
 extreme and the central group had a range of only 3.5 
 seconds as compared with 23 seconds for entire group. The 
 group of boys clusters more closely about the median and 
 seems of rather mediocre ability when judged by initial 
 trials, yet they finally attained a rate, based on time for 
 first fifty taps, superior to Gilbert's seven-year-old boys, 
 whose records are based on first five seconds. 
 
 1 P. E. was obtained by following formula : P. E. = 0.8433 X A. D., 
 where A. D. represents the average deviation from the average of 
 individual measurements. 
 
RATE OF VOLUNTARY MOVEMENTS 
 
 21 
 
 TABLE I 
 Showing Daily Averages in Tapping Test 
 
 
 Boys — Time in Seconds 
 
 Girls — Time in Seconds 
 
 Day 
 
 xst 50 
 Taps 
 
 2d 50 
 Taps 
 
 Total 
 
 Diff. 
 
 1st 50 
 Taps 
 
 2d 50 
 
 Taps 
 
 Total 
 
 Diff. 
 
 I— R.H. 
 
 15-75 
 
 17-25 
 
 33-00 
 
 1-5 
 
 13-58 
 
 15-00 
 
 28.58 
 
 1.42 
 
 L.H. 
 
 15-33 
 
 20.33 
 
 35-66 
 
 5-0 
 
 15.00 
 
 17.29 
 
 32.29 
 
 2.29 
 
 2— R. 
 
 15-30 
 
 15.66 
 
 30.96 
 
 0.36 
 
 12.38 
 
 14-23 
 
 26.61 
 
 1.85 
 
 L. 
 
 15.66 
 
 18.41 
 
 34-07 
 
 2.75 
 
 14-15 
 
 17.30 
 
 31-45 
 
 3-15 
 
 3-R. 
 
 12.33 
 
 13.16 
 
 25-49 
 
 0.83 
 
 II. II 
 
 13.34 
 
 24-45 
 
 2.23 
 
 L. 
 
 14.41 
 
 16.25 
 
 30.66 
 
 1.84 
 
 13-43 
 
 16.20 
 
 29-63 
 
 2-77 
 
 4-R. 
 
 10.00 
 
 13.40 
 
 23.40 
 
 3-40 
 
 10.22 
 
 13.04 
 
 23.26 
 
 2.82 
 
 L. 
 
 12.58 
 
 16.83 
 
 29.41 
 
 4-25 
 
 12.11 
 
 15.47 
 
 27-58 
 
 3-36 
 
 5-R- 
 
 10.15 
 
 12.16 
 
 22.31 
 
 2.01 
 
 10.31 
 
 12.54 
 
 22.85 
 
 2.23 
 
 L. 
 
 13-08 
 
 15-00 
 
 28.08 
 
 1.92 
 
 12.46 
 
 1519 
 
 27-65 
 
 2-73 
 
 6— R. 
 
 9.66 
 
 12.33 
 
 21.99 
 
 2.66 
 
 9.85 
 
 12.07 
 
 21.92 
 
 2.22 
 
 L. 
 
 12.83 
 
 14.66 
 
 27.49 
 
 1.83 
 
 12.17 
 
 15.24 
 
 27-41 
 
 3-07 
 
 7-R. 
 
 10.13 
 
 12.03 
 
 22.16 
 
 1.9 
 
 9.72 
 
 11.95 
 
 21.67 
 
 2.23 
 
 L. 
 
 12.73 
 
 16.50 
 
 29.23 
 
 3-77 
 
 11.84 
 
 14.73 
 
 26.57 
 
 2.89 
 
 8— R. 
 
 10.13 
 
 12.03 
 
 22.16 
 
 1.90 
 
 9.75 
 
 12.32 
 
 22.08 
 
 2.57 
 
 L. 
 
 12.90 
 
 16.16 
 
 29.06 
 
 3.26 
 
 11-65 
 
 13.71 
 
 25-36 
 
 2.06 
 
 9-R. 
 
 9-58 
 
 13-03 
 
 22.61 
 
 3-45 
 
 9-31 
 
 11.46 
 
 20.77 
 
 2.15 
 
 L. 
 
 12.00 
 
 15-33 
 
 27-33 
 
 3-33 
 
 11.64 
 
 14.74 
 
 26.38 
 
 3.09 
 
 10— R. 
 
 9.66 
 
 11.83 
 
 21-49 
 
 2.17 
 
 9.12 
 
 II. 18 
 
 20.30 
 
 2.06 
 
 L. 
 
 11.83 
 
 14.83 
 
 26.66 
 
 3.00 
 
 11-35 
 
 14.00 
 
 25-35 
 
 0.65 
 
 II— R. 
 
 9.73 
 
 11.43 
 
 21.16 
 
 1.70 
 
 9-57 
 
 11.20 
 
 20.77 
 
 1.63 
 
 L. 
 
 11.83 
 
 15.00 
 
 26.83 
 
 3.17 
 
 II. 10 
 
 13.66 
 
 24-76 
 
 2.55 
 
 12— R. 
 
 9.43 
 
 11.83 
 
 21.26 
 
 2.40 
 
 9.20 
 
 10.87 
 
 20.07 
 
 1.67 
 
 L. 
 
 12.50 
 
 14.16 
 
 26.66 
 
 1.66 
 
 11-47 
 
 13.61 
 
 25-08 
 
 2.15 
 
 1 3-R. 
 
 10.10 
 
 12.06 
 
 22.16 
 
 1.96 
 
 9-33 
 
 10.69 
 
 20.02 
 
 1.36 
 
 L. 
 
 12.00 
 
 14.66 
 
 26.66 
 
 2.66 
 
 10.83 
 
 13.53 
 
 24-36 
 
 2.70 
 
 14— R. 
 
 9.72 
 
 12.28 
 
 22.00 
 
 2.56 
 
 9.24 
 
 11.74 
 
 20.98 
 
 2.50 
 
 L. 
 
 11.80 
 
 15.20 
 
 27.00 
 
 340 
 
 11.20 
 
 13.16 
 
 24-36 
 
 1.96 
 
 15— R. 
 
 9.40 
 
 11.38 
 
 20.73 
 
 1-93 
 
 8.18 
 
 9.90 
 
 18.08 
 
 1.72 
 
 L. 
 
 13.00 
 
 14.00 
 
 27.00 
 
 1. 00 
 
 II. 10 
 
 12.71 
 
 23-81 
 
 I.6I 
 
 Average R. 
 
 10.73 
 
 12.79 
 
 23-52 
 
 2.049 
 
 10.06 
 
 12.10 
 
 22.16 
 
 2.046 
 
 L. 
 
 12.96 
 
 15.82 
 
 28.78 
 
 2.856 
 
 12.10 
 
 14.70 
 
 26.80 
 
 2.469 
 
 Table II shows the individual ranking in first trials and 
 in averages obtained as a measure of final efficiency. 
 
 Considering the right hands, it is noticeable that the boys 
 making best and poorest records on first trials make the 
 least change in final ranking. This same tendency is noted 
 in the girls and is more pronounced in the more inefficient 
 group. There was no case in which there was no change 
 in ranking, this varying from one step to two for boys; 
 from one step to six for girls. 
 
22 
 
 MOTOR ABILITIES OF CHILDREN 
 
 40 
 
 35 
 
 30 
 
 25 
 
 15 
 
 
 
 
 
 \ 
 
 
 
 
 \ >v 
 
 ^^-'<:. 
 
 
 
 
 
 ^ ^\ 
 
 
 IS 
 
 Fig. I. Tapping Test. Abscissa, Practice Periods. Ordinate, Time. 
 Boys, R. H. , L. H. . Girls, R.H. , L. H. . 
 
 The averages for left hands show much greater variation 
 from initial trials, this being more marked in the extremes 
 for the boys, in which group there were no left-handers. 
 
 TABLE II 
 Rank in Tapping Test 
 
 
 R. H. 
 
 L. H. 
 
 
 R. H. 
 
 L. H. 
 
 Boys 
 
 
 
 
 
 
 
 
 
 1st Day 
 
 ATerage 
 
 ist Day 
 
 Average 
 
 
 i»t Day 
 
 Average 
 
 ist Day 
 
 Average 
 
 a 
 
 4 
 
 6 
 
 3 
 
 4 
 
 A 
 
 I 
 
 2 
 
 10 
 
 4 
 
 b 
 
 5 
 
 3 
 
 6 
 
 2 
 
 B 
 
 7 
 
 4 
 
 4 
 
 3 
 
 c 
 
 6 
 
 5 
 
 5 
 
 3 
 
 C 
 
 9 
 
 6 
 
 7 
 
 8 
 
 d 
 
 3 
 
 I 
 
 4 
 
 I 
 
 D 
 
 8 
 
 10 
 
 2 
 
 2 
 
 e 
 
 2 
 
 4 
 
 I 
 
 6 
 
 E 
 
 12 
 
 13 
 
 I 
 
 6 
 
 f 
 
 I 
 
 2 
 
 2 
 
 5 
 
 F 
 
 4 
 
 I 
 
 5 
 
 I 
 
 
 
 
 
 
 G 
 
 II 
 
 12 
 
 8 
 
 II 
 
 
 
 
 
 
 H 
 
 13 
 
 II 
 
 13 
 
 12 
 
 
 
 
 
 
 I 
 
 3 
 
 7 
 
 12 
 
 13 
 
 
 
 
 
 
 J 
 
 6 
 
 5 
 
 9 
 
 10 
 
 
 
 
 
 
 K 
 
 
 
 8 
 
 3 
 
 9 
 
 
 
 
 
 
 L 
 
 10 
 
 9 
 
 II 
 
 ."i 
 
 
 
 
 
 
 M 
 
 5 
 
 3 
 
 6 7 
 
RATE OF VOLUNTARY MOVEMENTS 
 
 23 
 
 Of the girls D was decidedly left-handed and it is not 
 surprising that she kept her rank. E's left hand showed 
 slight superiority over right hand in final efficiency, but 
 was not consistently so throughout the series and drops 
 from I to 6 in rank. Again there are erratic changes in 
 ranks varying from i to 6 steps with no general tendency, 
 but the two most inefficient of this group make a change 
 of but one step. 
 
 These results show clearly that the initial trials are not 
 indicative of actual ability but are of diagnostic value in 
 detecting the extremes, or greatest variants in the normal 
 distribution. 
 
 A comparison of results is not of value unless the vary- 
 ing conditions are carefully noted. The following tabula- 
 tion for tapping with right hand shows the increase in rate 
 with age and sex differences. 
 
 No. Taps 
 in 1 Sec. 
 
 Sex 
 
 6.7 
 
 male 
 
 536 
 
 male 
 
 5.28 
 
 female 
 
 4-56 
 
 male 
 
 4-25 
 
 female 
 
 6.1 
 
 male 
 
 6.13 
 
 female 
 
 4.72 
 
 male 
 
 4-25 
 
 female 
 
 4.66 
 
 male 
 
 4-95 
 
 female 
 
 Age 
 
 Duration of 
 Trial 
 
 Marsh 
 
 Burt 
 
 Gilbert 
 
 Bolton 
 
 Bolton 
 
 Bryan 
 
 Our average 
 rate 
 
 2&-34 
 I2|-I3i 
 
 8^ 
 8^ 
 
 6 
 
 6 
 
 5-8 
 5-8 
 
 Time for 100 
 
 Taps 
 
 IS Seconds 
 
 10 
 
 ID 
 
 The vaHdity of the initial trial, or the average of less than 
 five trials, as a measure of ability is again questioned by 
 certain differences in individual records during early trials. 
 It does not seem expedient to give all the individual 
 records and curves, but a study of a few of the imusual 
 ones suggests the importance of considering some of the 
 individual differences that are completely covered up in the 
 averages. 
 
 In general the individual curves correspond in form to 
 
24 
 
 MOTOR ABILITIES OF CHILDREN 
 
 the group curve. The left-handers, as D, having very 
 similar curves to a right-hander, save for change of place 
 and, perhaps, less distance apart. 
 
 There was one girl, K, whose record for first day was 
 better than that for second, third, and fourth days and 
 final average, both with right and left hand, though she 
 
 Fig. 2. Subject K. Tapping Test. Abscissa, Practice Periods. Ordi- 
 nate, Time. R. H. , L. H. . 
 
 attained a speed on several other days three seconds faster 
 than the first day rate. 
 
 Figure 2 shows curve of individual K. If abnormal 
 physiological condition prevailed during the three days of 
 diminished speed it was not evident. This subject did have 
 a cold the second week and the vitality may have been 
 lower just preceding it. 
 
 Figure 3 shows curve for I, whose left hand was so 
 poorly controlled. Her right hand curve is normal, her 
 average for it being median value for group, but the hands 
 are very far apart. She seemed to have used her left hand 
 
RATE OF VOLUNTARY MOVEMENTS 
 
 25 
 
 but little and to be really averse to using it. Her awkward 
 holding of stylus with left hand and variation in rate for 
 last fifty seconds were noted. There was a tendency when 
 
 40 
 
 35 
 
 30 
 
 25 
 
 IS 
 
 A 
 
 \ / \ 
 
 V, 
 
 y\ A 
 
 20 II 15 
 
 Fig. 3. Subject I. Tapping Test. Abscissa, Practice Periods. Ordi- 
 nate, Time. R. H. , L. H. . 
 
 nearly fifty taps had been made to change from holding 
 stylus in fingers to grasping in palm ; to pound slowly upon 
 plate, and to move right hand in correspondence with left. 
 
 Figure 4 shows curve for subject H, whose initial rate 
 was exceedingly slow and left hand also under poor control. 
 There is here a marked resemblance in form of two curves, 
 but the hands are far apart. 
 
 Of those tested on the first day who were present as 
 many as nine days, four girls and four boys failed to do 
 as well on the second day. These records showed much 
 irregularity for several days, some not again attaining 
 speed of first day until fourth or fifth day. 
 
 Wells's (22) interpretation of difference between first 
 and second trials with women, who surpassed men with 
 
26 
 
 MOTOR ABILITIES OF CHILDREN 
 
 right hand in first trial but were elsewhere inferior, as due 
 to aflfective variability, — a sex characteristic of not being 
 so interested after the novelty had passed away,— is not in 
 agreement with these findings for children. It seems not 
 
 2 6 II 13 
 
 Fig. 4. Subject H. Tapping Test. Abscissa, Practice Periods. 
 
 nate. Time. R. H. 
 
 L. H. 
 
 Ordi- 
 
 to be a rule, but rather that individual characteristics, with 
 perhaps environmental or physiological factors, cause such 
 exceptions in both sexes. 
 (2) Index of Fatigue. 
 
 The difference in daily averages of time required for 
 first and second fifty taps indicates the loss in rate from 
 fatigue. These differences are given in Table I under Diff. 
 
 We computed the fatigue index by taking the percentage 
 of this difference to the efficiency for the first fifty taps, ob- 
 taining the following results. 
 
 Fatigue-index for boys, R. H. 19% ; girls 20%. 
 
 Fatigue-index for boys, L. H. 22%; girls 20%. 
 
 These are lower than that of 24% found by Gilbert for 
 children eight years old, showing perhaps an increased 
 immunity to fatigue through practice. 
 
 We also computed the average daily deviations of the 
 fatigue loss, finding : 
 
RATE OF VOLUNTARY MOVEMENTS 27 
 
 A. D. for R. H. Boys 0.5771 ; Girls 0.354. 
 
 A. D. for L. H. Boys 0.8442 ; Girls 0.5462. 
 
 From these we obtain the probable error^ of the differ- 
 ence between the averages for boys and girls. 
 
 P. E. for R. H. 0.233 ; L- H. 0.345. 
 
 The difference of 0.003 for right hand is only 0.028 times 
 its probable error; that of 0.387 for left hand, 1.12 times 
 its probable error. We can not conclude the slight differ- 
 ences are significant of sex differences in loss from fatigue. 
 The difference for left hands is of more significance and 
 may be accounted for by the decided left-handedness of 
 two of the girls. 
 
 The greater fatigue index for boys with the left hand 
 is characteristic of a normal distribution. In case of girls 
 the equality in percentages for both hands is not surprising, 
 because of the individual variations already noted. 
 
 There appears to be no definite connection between rate 
 and fatigue loss within the limits of this experiment. The 
 boy and girl making best speed for one hundred taps had 
 a relatively low fatigue index. Other subjects were 
 irregularly arranged as to rank in rate and in loss by 
 fatigue. In the first few trials, there is a tendency to 
 lessen speed at the onset of fatigue, but to increase energy 
 by pounding on plate. Practice tends to eliminate the keen 
 sensations of fatigue and the increased force in striking. 
 
 In order to study more carefully the relation between 
 rate and fatigue, as objectively shown by decrease for last 
 fifty taps, two girls and one boy were given tests of longer 
 duration in the laboratory. A series of trials, ranging from 
 three to five, were given during one laboratory period, with 
 intervals of ten minutes between trials. A trial consisted 
 
 1 P. E. of mean was obtained by following formula: P. E.m 
 0.8453 
 = . A. D., where n is total number of individual measure- 
 
 V n — I 
 ments, and A. D. is average deviation. 
 
 P. E. of the difference between two means, Mi and M,, was found 
 
 as follows: P. E.d = VpTE.Mi' — ^" E-Jf«=. 
 
28 
 
 MOTOR ABILITIES OF CHILDREN 
 
 of one hundred taps with right hand ; after a minute's rest, 
 one hundred taps with left hand. These children came to 
 the laboratory once a month during five months. 
 
 Averages for individuals are given in following table. 
 
 
 
 
 TABLE III 
 
 
 
 
 
 
 Age 
 
 R. H. 
 
 L. H. 
 
 
 (0 
 
 {") 
 
 T. 
 
 D. 
 
 (0 
 
 (=) 
 
 T. 
 
 D. 
 
 W. girl 10 
 
 X. girl 8 
 
 Y. boy 1 8 
 
 8.98 
 8.17 
 903 
 
 10.31 
 9.00 
 9-47 
 
 19.29 
 17.17 
 18.51 
 
 1-33 
 0.83 
 0.44 
 
 9"i 
 
 7.71 
 8.63 
 
 11.60 
 
 8.51 
 
 10.41 
 
 20.77 
 16.22 
 19.09 
 
 1.88 
 
 .80 
 
 1-73 
 
 (i) and (2) columns have number of seconds required 
 for first and second fifty taps. T. is total of (i) and (2). 
 D. is difference between (i) and (2). 
 
 There is again no direct correlation of rate with fatigue. 
 Greater fatigue occurs when rate is slowest, save in case 
 of boy's right hand. He preferred use of left hand but 
 development of right-hand ability had almost resulted in 
 ambidexterity, as the slight difference between the two 
 records shows. 
 (3) Left-handedness. 
 
 The individual records give convincing evidence that the 
 tapping test is a most reliable one for securing an index 
 of left-handedness. The two girls of the regular group 
 who were left-handed were consistently so throughout the 
 series. There were a few trials in which scores for hands 
 were equal. This was also true for the right-handed 
 group. One exceptional case was X, whose record is given 
 in Table III. Her first day's records showed a superiority 
 of one second in rate for right hand. Her left hand was 
 decidedly superior in later records and in final average. 
 
 We computed the percentage of left-hand to right-hand 
 efficiency, by finding excess of time required for left- 
 hand as compared with rate for right-hand. This gives for 
 boys an index of 79.2% ;. for girls, 78.870- This is somewhat 
 surprising when we have two left-handed girls in group 
 
RATE OF VOLUNTARY MOVEMENTS 
 
 29 
 
 and no boys that are left-handed. We believe the explana- 
 tion is found in the records of girls I and H, that have been 
 given, whose left hands were exceptionally poor, far ex- 
 ceeding in inferiority the records of the right hands of the 
 two girls who were left-handed. 
 (4) Sex Differences. 
 
 In Table IV the individual averages for boys and girls 
 are given. The capital letters represent individual girls, 
 the small letters individual boys, (i) and (2) refer to 
 first and second fifty taps. Numbers in columns are time in 
 seconds. A. D. is average deviation. 
 
 TABLE IV 
 
 Boys 
 
 
 
 Girls 
 
 
 R. H. 
 
 L 
 
 H. 
 
 
 R. H. 
 
 L. H. 
 
 
 (0 
 
 (=) 
 
 («) 
 
 (") 
 
 (I) 
 
 (») 
 
 (i) 
 
 M 
 
 a 
 
 12.16 
 
 13-57 
 
 12.50 
 
 16.48 
 
 A 
 
 8.88 
 
 10.54 
 
 11.04 
 
 13-98 
 
 b 
 
 10.17 
 
 12.30 
 
 12.28 
 
 14.28 
 
 B 
 
 9-36 
 
 II. 15 
 
 10.86 
 
 i3-«9 
 
 c 
 
 11.64 
 
 13-63 
 
 12.69 
 
 15-34 
 
 <- 
 
 9.81 
 
 11.20 
 
 11-54 
 
 15-43 
 
 d 
 
 10. II 
 
 11.48 
 
 12.10 
 
 13.66 
 
 D 
 
 11-33 
 
 13-33 
 
 10.18 
 
 12.46 
 
 e 
 
 10.12 
 
 12.88 
 
 13-45 
 
 16.76 
 
 E 
 
 11.62 
 
 13.92 
 
 11.65 
 
 13.70 
 
 f 
 
 10. 16 
 
 12.06 
 
 13-13 
 
 16.86 
 
 F 
 
 8.48 
 
 10.20 
 
 10.26 
 
 11.86 
 
 
 
 
 
 
 G 
 
 11.42 
 
 13-73 
 
 13-40 
 
 16.40 
 
 
 
 
 
 
 H 
 
 11.26 
 
 13.62 
 
 1556 
 
 17.81 
 
 
 
 
 
 
 I 
 
 9-75 
 
 12.50 
 
 15-37 
 
 18.40 
 
 
 
 
 
 
 1 
 
 10.08 
 
 10.60 
 
 12.60 
 
 15-13 
 
 
 
 
 
 
 K 
 
 10.24 
 
 12.40 
 
 12-33 
 
 15-27 
 
 
 
 
 
 
 L 
 
 10.35 
 
 12.80 
 
 11.46 
 
 13-63 
 
 
 
 
 
 
 M 
 
 8-74 
 
 11-30 
 
 12.04 
 
 13-68 
 
 Av. 
 
 10.72 12.65 
 
 12.67 
 
 15-56 
 
 
 10.10 
 
 12.10 
 
 12.17 
 
 14-74 
 
 A. D. 
 
 0.782 0.706 
 
 0.415 
 
 I-I3 
 
 
 0.864 
 
 1. 169 
 
 1.368 
 
 1-538 
 
 Total Av. 2X.'\7 
 
 2i 
 
 !-25 
 -99 
 
 
 22 20 
 
 26.91 
 
 25-37 
 
 Median 22.73 
 
 2/ 
 
 
 22.25 
 
 The time required by girls for one hundred taps was 
 1. 1 79 seconds less for right hand; 1.334 seconds less for 
 left hand than that required by boys. In each case the 
 left hand range was greater than the right and the range 
 of girls exceeds that of the boys. 
 
 To correct the error due to unequal distribution of sexes 
 and to small number tested, the probable error of the dif- 
 
30 MOTOR ABILITIES OF CHILDREN 
 
 ference between the averages of boys and girls was found. 
 P. E. of difTerence for R. H. 0.365 
 P. E. of difference for L. H. 0.447 
 Since the difference for right hand is 3.23 times its P. E., 
 for left hand 3.98 times its P. E., these differences must 
 be a valid indication of sex differentiation. 
 
 To summarize the results from the tapping test for sub- 
 jects studied, we may note : 
 
 That there is marked improvement due to practice with 
 great irregularity in early trials. 
 
 That the initial trial, or average of less than five trials, 
 does not give a true indication of actual ability in rate of 
 movement. 
 
 That the loss from fatigue is not directly correlated with 
 rate, but varies irregularly ; is not a distinct sex character- 
 istic ; and the index is greater for use of hand not preferred. 
 
 That there is a distinct sex differentiation in ability in 
 tapping test in favor of girls. 
 
 That the index of right-handedness obtained, in accord- 
 ance with the results of other investigators, shows more 
 pronounced ei^ciency in use of preferred hand during child- 
 hood than in adult life. 
 
V. STEADINESS OF MOTOR CONTROL 
 I. Apparatus 
 
 Measurement of involuntary movements was made by 
 method similar to that described in Whipple's (24) Manual, 
 Test 13. The brass plate had a series of holes arranged in 
 two rows. Beginning with the one in the lower left-hand 
 corner, the diameters of the holes were respectively 32, 28, 
 24, 20, 16, 12, ID, 9, 8, 7 and 6 sixty-fourths of an inch. 
 The first five, which were in lower row, were the only ones 
 reached within the limits of this experiment. The stylus 
 consisted of a metallic needle one-sixteenth of an inch in di- 
 ameter and one and five-eighths of an inch long, in a wooden 
 cylindrical handle three-eighths of an inch in diameter and 
 four inches long. The weight of stylus was twelve and a 
 half grams. Plate, stylus, and a telephone receiver were 
 wired in series with battery so that contact between needle 
 and plate caused a click in the receiver. Graphic record 
 was not made, and we recognize the source of error in the 
 counting of strokes made by sounder when tested. The 
 very short, rapid contacts produced such noticeable clicks, 
 we believe the probability of errors in correct counting to 
 be so small as not to cause significant differences in results. 
 A stop-watch was used to time the trials. 
 
 2. Method of Conducting Test 
 
 Before the test was given each child was allowed to put 
 the receiver to his ear and with stylus in other hand make 
 the contact. Then it was explained to him that he was 
 to make as few contacts as possible during his test. He 
 stood at a distance from the table a little greater than the 
 length of the arm from the elbow and with shoulder of arm 
 used in front of plate. Hand and arm were free from all 
 
 31 
 
32 
 
 MOTOR ABILITIES OF CHILDREN 
 
 support or contact with body. Plate was set flush with 
 edge of table and adjusted at an angle such that the stylus 
 was held perpendicular to plane of plate. Each subject 
 was allowed three seconds to get needle in position before 
 watch was started. Time for trial was fifteen seconds. 
 Only two children were in room with experimenter at same 
 time. Right hand was tested first in each hole, beginning 
 with the largest, until the number of contacts in one hole 
 equalled or exceeded twelve. Between tests for each hole 
 fifteen seconds were given for resting arm. The left hand 
 was then tested in similar manner. 
 
 3. Subjects 
 
 The subjects were same as those in tapping test. The 
 first steadiness test was given before the practice series in 
 tapping, the second afterward. Records are for seventeen 
 girls and eight boys. 
 
 4. Computation of Results 
 
 The numbers of contacts made in each hole are averaged, 
 separately for sexes, and the total number of contacts for 
 the five holes is also given. Taking hole three as the 
 one most satisfactorily testing the steadiness of these sub- 
 jects, the average deviation of individuals from the group 
 average was computed for right hand in hole three. The 
 probable error of the difference between these averages for 
 sexes was obtained, as a measure of the reliability of the 
 sex diiTerence. 
 
 5. Results 
 
 In Table V the records from both tests, averaged for 
 sexes, are shown for the five holes. 
 
 TABLE V 
 
 Total 
 
 Boys 
 Girls 
 Boys 
 Girls 
 
 I 
 
 2 
 
 3 
 
 4 
 
 5 
 
 1.06 
 
 2. 
 
 5-12 
 
 6.43 
 
 10.75 
 
 0.94 
 
 1-47 
 
 3-35 
 
 4.64 
 
 10.09 
 
 3- 1 2 
 
 443 
 
 5.81 
 
 «.95 
 
 10.5 
 
 3-25 
 
 4.82 
 
 7-37 
 
 10.18 
 
 14.1 
 
 25-36 
 20.49 
 32.81 
 
 39-72 
 
STEADINESS OF MOTOR CONTROL 33 
 
 In this test it is generally agreed that elimination of cer- 
 tain factors, as distraction and moving of body, is of more 
 importance than the repetition of tests. Children respond 
 to the slightest external stimulus. Under seemingly most 
 desirable conditions for experimentation one boy made a 
 very poor record, which was somewhat explained by his 
 statement later that his father owned an engine for cutting 
 wood. A slight buzzing sound that came through the 
 window was found to be from a wood yard near the school. 
 
 The trick in method, control of respiration, is not de- 
 veloped by the children, but the disturbance in respiration 
 is very evident. 
 
 The movements with some are slight but almost con- 
 tinuous. In others there are larger movements more spas- 
 modic. These also vary as to form. A sidewise or 
 irregularly circular motion prevails with some, while in 
 others there is a tendency to go forward, then back. One 
 girl would sometimes let needle of stylus go almost its 
 entire length through a hole and back again without a con- 
 tact. This was with right hand. The same form of move- 
 ment occurred with left hand, but was not so well con- 
 trolled, 
 (i) Practice Effects. 
 
 When the averages of contacts made in each hole are 
 considered separately for the two tests, both sexes show 
 slight improvement with both hands in second test. This 
 was not true of all individual records or for both hands in 
 same individual. The boy who made best record of entire 
 group in both tests made best score in first test. 
 (2) Sex Differences. 
 
 Girls are superior with right hand, boys with left. The 
 exceedingly poor coordination with left hand by two girls 
 may partially explain the latter result. Subject I again 
 showed the same distance between her hands. In hole two, 
 with right hand, she made in first and second test respec- 
 tively six and two contacts; with left hand, sixteen and 
 seventeen contacts. 
 
34 
 
 MOTOR ABILITIES OF CHILDREN 
 
 Taking records for right hand in hole three we find an 
 average deviation for girls of 2.53 contacts ; for boys, 4.45 
 contacts. The probable error of the difference 1.77 be- 
 tween their averages is 0.553. The difference is 3.2 times 
 
 12 3 4 5 
 
 Fig. 5. Steadiness Test. Abscissa, Number of Hole. Ordinate, 
 
 Averaged Number of Contacts. Boys, R. H. , L. H. — . 
 
 Girls, R. H. , L. H. . 
 
 its P. E. and indicates superiority of the girls with right 
 
 hand. 
 
 (3) Index of Right-handedness. 
 
 The results for individuals vary from test to test with 
 hole and with hand used. Shifts in superiority from right 
 to left hand and vice versa are noticeable. Of the two left- 
 handed girls as determined by tapping test, only one was 
 left-handed in steadiness test. For boys the index of right- 
 handedness is yy% ; for girls, 51%. This shows clearly the 
 inefficiency of left hands of certain individuals in the group 
 of girls. 
 
 The difficulty of control in this test and the covering up 
 of actual measurement by averages for groups that may 
 include extreme departures from the mode invalidate many 
 results. If a number sufficiently large could be selected, by 
 elimination of the extremes, a norm might be established. 
 It is to be questioned if results of Woolley and Fischer (23) 
 from tests given a year apart and at the time children four- 
 
STEADINESS OF MOTOR CONTROL 35 
 
 teen and fifteen years old came to apply for working cer- 
 tificates, justify their vocational diagnosis, that for "posi- 
 tions requiring strength or mere rapidity of motion 
 (particularly at fifteen years) boys would be better. For 
 those requiring steadiness or fine motor control, girls would 
 be better." 
 
VI. REACTION TIMES 
 I. Apparatus 
 
 In measuring the reaction time of children to visual 
 stimulus, we believed an object of interest to a child would 
 be a better stimulus than mere geometrical designs such as 
 are frequently used. Transfer pictures of a dog and bird 
 were put on the milk glass plate in the screen used for 
 displaying the stimulus. By means of an electric bulb just 
 behind the plate and a slide with a rectangular opening, 
 either object desired could be shown. The connections 
 between operating keys, the D'Arsonval chronoscope, and 
 light behind screen were such that when the experimenter 
 pressed the keys the picture appeared and simultaneously 
 the hand started, and when child squeezed a bulb the hand 
 stopped. 
 
 2. Method of Conducting Test 
 
 The subject sat within a shaded compartment, just in 
 front of screen, with arm in comfortable position, and hold- 
 ing a rubber bulb in right hand. Only a black curtain 
 separated the subject from the experimenter, so that the 
 passage of air when bulb was squeezed was sometimes 
 heard when subject responded too soon. Caution was given 
 that the noises incident to giving or changing stimulus were 
 not to be heeded as significant in any way. To prevent re- 
 sponse to noises, similar ones were given each time. The 
 slide was pushed back and forth whether picture was 
 changed or not. Time between changing of slide and giv- 
 ing of stimulus was also varied to prevent a rhythmical 
 response. We believe, however, that the elimination of all 
 other stimuli than the visual was not so successful but that 
 occasional errors entered. When the time was varied be- 
 tween click and appearance of picture, reaction was often 
 
 36 
 
REACTION TIMES 37 
 
 made too soon. Some very short reactions may have been 
 due to this anticipatory response. 
 
 Simple reaction times were first obtained by giving 
 preferred object, bird to three girls, dog to one girl and one 
 boy. After one hundred simple reactions were made, the 
 discriminative reactions were begun. In the latter case, 
 the subject was to respond to the object as previously given, 
 but not to respond when the other appeared. Finally 
 another one hundred simple reactions were made. 
 
 Some preliminary tests were given in order to find out 
 the number of reactions that could be made during a sitting 
 without too great fatigue and the number of sittings de- 
 sirable during a laboratory period. The boy Y had been 
 given one hundred simple reactions in the spring of 191 5> 
 responding to five circular dots. He was given a few more 
 with the dog to note any difference that might occur be- 
 cause of stimulus. His interest" was so keen in his first 
 work at the laboratory that no marked difference appears 
 and his average is made from the total number of simple 
 reactions. 
 
 During the early preliminary trials bird or dog was chosen 
 at random and listed. For the real tests, order of presenta- 
 tion was chosen by use of deck of cards. The children 
 held themselves under rather high tension in anticipation, 
 of stimulus. This was not maintained to so great a degree 
 during later and shorter sittings. During first simple re- 
 actions, twenty-five were made at a sitting. It was found 
 best to give only ten presentations at one sitting, and this 
 procedure was adopted for the discrimination reactions and 
 for the second series of simple reactions. By giving a rest 
 of ten minutes between sittings it was easy to get twenty- 
 five reactions, or to give fifty presentations, during a period. 
 This work was begun the latter part of October, 191 5, and 
 continued through March, 1916, with intervals of two to 
 four weeks between laboratory periods. 
 
38 
 
 MOTOR ABILITIES OF CHILDREN 
 
 3. Subjects 
 
 Four girls and one boy, children of professors of the 
 University, were used in the reaction time experiment. 
 They ranged in age from four to ten years. The four- 
 year-old made only simple reactions. 
 
 They were evidently pleased to come to the laboratory 
 and seemed to enjoy various tests undertaken. The reac- 
 tions were interesting at first but the monotony necessarily 
 involved proved irksome to the children. Only by short 
 sittings and because of the pleasure of getting to the labora- 
 tory were they sufficiently stimulated to complete the tests. 
 
 4. Treatment of Data 
 
 Averages were obtained for the total number of reac- 
 tions. For some subjects this number varied slightly from 
 the one hundred planned, but we deemed it advisable to 
 average unquestioned scores just as they were. Number 
 of reactions, maximal and minimal reaction time, and num- 
 ber of errors in discrimination reactions are also listed. 
 The reaction times are expressed in thousandths of a second, 
 
 5. Results 
 
 Tables VI and VII give our resultant values from aver- 
 ages for individuals and also show Gilbert's results. His 
 averages for the ages are based on median value of ten 
 reactions from fifty of each sex, the discrimination reaction 
 preceding the simple. 
 
 TABLE VI 
 Simple Reaction Times 
 
 
 s« 
 
 Age 
 
 Preceding Discrimination 
 
 After Discrimination 
 
 Indiv. 
 
 No. of 
 
 Av. 
 
 Max. 
 
 Min. 
 
 No. of 
 
 Av. 
 
 Time 
 
 Mai. 
 
 Min. 
 
 Gil- 
 
 bert's 
 
 
 
 
 Trials 
 
 in <r 
 
 Time 
 
 Time 
 
 Trials 
 
 in a 
 
 Time 
 
 Time 
 
 Av. in cr 
 
 z 
 
 girl 
 
 4 
 
 105 
 
 428 
 
 1050 
 
 100 
 
 
 
 
 
 
 V 
 
 girl 
 
 6 
 
 100 
 
 415 
 
 1000 
 
 100 
 
 100 
 
 2.^9 
 
 650 
 
 40 
 
 295 
 
 X 
 
 girl 
 
 8 
 
 132 
 
 315 
 
 6,-^8 
 
 77 
 
 100 
 
 220 
 
 7. SO 
 
 30 
 
 260 
 
 Y 
 
 boy 
 
 8 
 
 160 
 
 263 
 
 600 
 
 160 
 
 100 
 
 130 
 
 310 
 
 20 
 
 245 
 
 w 
 
 girl 
 
 10 
 
 102 
 
 250 
 
 640 
 
 no 
 
 100 
 
 127 
 
 350 
 
 20 
 
 225 
 
REACTION TIMES 
 
 TABLE VII 
 Discrimination Reactions 
 
 39 
 
 
 
 
 No. of 
 
 
 Max. 
 
 Min. 
 
 No. of 
 
 Gilben's 
 
 
 Sex 
 
 Age 
 
 Trials 
 
 in <r 
 
 Time 
 
 Time 
 
 Errors 
 
 Av. in «r 
 
 V 
 
 girl 
 
 6 
 
 77 
 
 404 
 
 II50 
 
 60 
 
 II 
 
 510 
 
 X 
 
 girl 
 
 8 
 
 140 
 
 324 
 
 1300 
 
 80 
 
 13 
 
 475 
 
 Y 
 
 boy 
 
 8 
 
 100 
 
 253 
 
 850 
 
 40 
 
 8 
 
 480 
 
 W 
 
 girl 
 
 10 
 
 «4 
 
 187 
 
 650 
 
 20 
 
 8 
 
 415 
 
 The simple reaction time for trials preceding the dis- 
 crimination are longer even than the discrimination reaction 
 times, with the exception of the eight-year-old girl, and 
 much longer than those found by Gilbert for subjects of 
 same age. These latter were made after his discrimination 
 reactions, but his trials were so few the effect of practice 
 does not sufficiently explain the difference. His results are 
 the averages for a large number of subjects and based on 
 the median value for a subject, so not actually comparable 
 with the individual records we have listed. 
 
 It was to be expected that the greater practice would 
 make the simple reaction times for the last series shorter 
 than the first, but it was surprising to note that in two cases 
 they are much shorter than the time Gilbert found for the 
 subjects seventeen years old, boys 147; girls 163. This is 
 representative of the normal simple reaction time of adults 
 found by other investigators. 
 
 As a child more fully understood just what was expected 
 of her, and also realized that other children were doing the 
 same thing, a spirit of competition developed. This was not 
 purposely encouraged but was a natural development evi- 
 denced by such remarks as, " Do I do as well as the others? " 
 and, " Oh, I tried not to go too soon." This latter remark 
 also indicates the anticipatory state in which the child was 
 so ready to respond that the reaction would often have been 
 made whether the stimulus appeared or not. The objective 
 evidence of this was given when the time of giving stimulus 
 was varied and reactions were made too soon. 
 
 The discrimination times reported by Gilbert are rather 
 
40 MOTOR ABILITIES OF CHILDREN 
 
 long, but one who has noted the lengthened period of ad- 
 justment necessary for young children would expect such 
 from the few trials. The records we have obtained com- 
 pare most favorably with those for adults. Gilbert's aver- 
 age in discrimination for those seventeen years old is for 
 boys 305; for girls 315. The number of errors we found 
 was not excessive. Premature responses were not so fre- 
 quent as in the simple reactions. The inhibition that pre- 
 vented response to wrong stimulus seems carried over into 
 inhibition of premature responses. The extremely short 
 minimal times seem to be partly due to chance. Subject W 
 once remarked, " I'm so glad it was a bird. I believe I 
 would have pressed if it had been a dog." 
 
 While for these few subjects there is increasingly 
 shortened reaction with increasing age, the averages ap- 
 proximate much more closely those for adults than results 
 in other motor tests have done. Usually the adult records 
 are based on fewer trials and perhaps upon more fatiguing 
 periods of experimentation than were practical for the 
 children. A most interesting problem would be a prolonged 
 comparative study of reaction times for different ages, de- 
 termined under same conditions. 
 
VII. ACCURACY OF MOVEMENT 
 I. Apparatus 
 
 A wooden board 26 by 37 inches was painted black and 
 sanded to prevent sliding of bags. On this board four 
 concentric circles were described in white paint. The cen- 
 tral circle had a diameter of six inches ; the others, re- 
 spectively, twelve, eighteen, and twenty-four inches. The 
 board was divided into halves, both horizontally and ver- 
 tically, by two straight lines intersecting in the center of 
 the system of circles. There was an adjustable support, 
 so the board could be inclined at such an angle that the bags 
 would fall perpendicularly upon it. The bags were circular, 
 three and a half inches in diameter, filled with rice, and 
 weighed fifty-four grams. 
 
 2. Method of Conducting Test 
 
 The board was placed upon the floor against a wall. 
 Each subject stood at a distance of six feet from the lower 
 edge of board, and in such position that the arm used was 
 in line with the vertical line upon board. His aim was the 
 center of the circles where the straight lines intersected. 
 Freedom in manner of throwing was given as to tossing or 
 overhand throw. Only occasionally was the latter used. 
 Tossing the bag proved to be a more accurate method and 
 was adopted by all. 
 
 Groups of twelve children, six boys and six girls, will be 
 designated according to intervals between practice. The 
 five-days-a-week group were given ten throws with each 
 hand, the right preceding, on each school day for the first 
 three weeks in December, between eleven and twelve 
 o'clock. 
 
 The Tuesday-and-Thursday group were practiced from 
 
 41 
 
42 MOTOR ABILITIES OF CHILDREN 
 
 ten to eleven o'clock on the days mentioned until the total 
 number of throws equalled that of the first group. 
 
 The once-a-week group were given twenty throws with 
 each hand on Thursdays between nine and ten o'clock. 
 
 The once-in-two-weeks group had ten throws with each 
 hand on Tuesdays from nine to ten o'clock. During the 
 later practice periods these were given fifteen throws with 
 each hand. They were somewhat younger than the once-a- 
 week group and because of fatigue effects it was thought 
 best to give only ten throws at the beginning, but later the 
 fifteen throws seemed desirable. 
 
 The Christmas holidays made an interval of two weeks 
 without practice for all the groups save the first. In each 
 case periods were arranged so that one hundred and forty 
 throws were made with each hand, the right preceding. If 
 a child was absent more than three times, he was eliminated. 
 
 3. Sources of Error 
 
 Since the line of motion varied from throw to throw, 
 the bag did not fall perpendicularly upon the board each 
 time. When it did, it remained where it first touched. 
 With varj'ing trajectories given by the tosser, the bag met 
 the board at varying angles. This, together with force of 
 throw, caused the bag to skid or to turn over at times. By 
 noting exact difference this made in score of several indi- 
 viduals during a number of practice periods, it was found 
 that the error was never greater than one on a single throw 
 or three for a practice period with one hand. There was 
 rarely a change in score unless bag fell in line with center 
 and it is evident that here the errors on the upper side tend 
 to counter-balance those on the lower side. 
 
 An attempt was then made to ascertain any constancy as 
 to portion of board struck by individual thrower. There 
 was no regularity as to direction of error for the subjects 
 who were studied for this purpose. We believe the scores 
 are representative, the slight residue of errors from these 
 sources being as probable for one subject as another. 
 
accuracy of movement 43 
 
 4. Method of Scoring and Computation of Results 
 
 If the bag fell within the inner circle it touched the 
 central point and the score recorded was four; within the 
 next circle, three; the next, two; the outer circle, one. If 
 partly in one, then the score was recorded for that circle 
 within which it clearly lay. Anywhere outside the outer 
 circle was scored zero. The total individual score for a 
 practice period was divided by the number of throws made 
 and the quotient recorded. The records for subjects within 
 a group were averaged for each practice period. The curves 
 were drawn according to these averages. Final averages 
 for the sexes were obtained for group comparisons. The 
 average daily deviations from the final average and the 
 probable errors were also calculated as a measure of relia- 
 bility of score. 
 
 5. Results 
 
 The tables VIII, IX, X, and XI give the average per- 
 formance of each group, a statement of the average devia- 
 tion, and the probable error of the difference between the 
 averages for the sexes. 
 
 5-Days-a-Week Group 
 
 The average age of this group was six years, seven months 
 for girls, within a range of one year, one month ; for boys, 
 six years, two months, ten days, within a range of five 
 months. Records given are for five girls and five boys. 
 
 While the individual differences in efficiency are largely 
 eliminated in the consideration of the averages for the 
 groups as a whole, they do enter into the computation of 
 rate and amount of improvement for a particular group in 
 a way that causes a defect so far as practice effects are 
 concerned. The majority in a group might show slight im- 
 provement on one day, yet if the best performers of the 
 preceding day chanced to make unusually poor throws, the 
 final average for that day would be lower. 
 
 The experiments were necessarily extended throughout 
 
44 
 
 MOTOR ABILITIES OF CHILDREN 
 
 TABLE VIII 
 
 Showing the Daily Averages for the Five-Days-a-Week Group 
 
 
 Girls 
 
 Boys 
 
 
 R. H. 
 
 L. H. 
 
 R. H. 
 
 L. H. 
 
 I 
 
 2 
 
 3 
 4 
 5 
 6 
 
 7 
 8 
 
 9 
 
 10 
 
 II 
 
 12 
 
 13 
 14 
 
 I-S 
 1-9 
 1-725 
 2-075 
 
 1.6 
 
 1-4 
 
 1-833 
 
 1-7 
 
 1-9 
 
 1.6 
 
 1.56 
 
 1.72 
 
 1-44 
 
 1-4 
 
 1-475 
 0.98 
 
 1-475 
 1-25 
 1.2 
 1.2 
 
 1-433 
 
 1.2 
 
 1.6 
 
 1-4 
 
 1.32 
 
 1.66 
 
 1-34 
 
 1-15 
 
 2.033 
 
 1-633 
 
 1-9 
 
 1-633 
 
 1.62 
 
 1.66 
 
 1-383 
 1.48 
 
 1-54 
 1-55 
 1.283 
 
 1-35 
 1.416 
 
 1-54 
 
 1-3 
 1-3 
 
 ;:i5 
 
 1.06 
 0.98 
 1. 116 
 
 1-38 
 
 1.06 
 
 1-133 
 1-083 
 
 1. 00 
 
 1-25 
 1.26 
 
 Total 
 
 Av 
 
 23-353 
 1.668 
 0.168 
 
 18.683 
 
 1-334 
 0.148 
 
 22.021 
 
 1-573 
 0.148 
 
 16.272 
 1.62 
 
 A. D 
 
 0.102 
 
 Difference between averages for R. H. 0.095 
 
 L. H. 0.172 
 Probable error of R. H. difference 0.0945 
 L. H. difference 0.0759 
 
 such a long period absences were unavoidable. We could 
 not eliminate all who were absent for any period because it 
 reduced the groups too much for study. The absence of a 
 thrower who was above the average ability reduced the 
 score for that day as compared with the preceding practice 
 period. 
 
 In many individuals there was a continued but irregular 
 improvement. This was shown especially by those who 
 were poor in coordination at the beginning, frequently fail- 
 ing to hit the board. 
 
 The curve for the right hand of girls is similar to the 
 general learning curve, with more irregular gains during 
 the first five days. On the sixth and last day the records 
 are inferior to that for first day. With the left hand there 
 are fluctuations of considerable magnitude. On three days 
 later in the series records equalled or excelled that of the 
 
ACCURACY OF MOVEMENT 
 
 45 
 
 first day, but elsewhere no improvement was shown and 
 the final average is less than the score for first day. 
 
 The initial record for boys was superior to any later 
 record and to final average for boys' right hand. With 
 left hand there were only three days in which improvement 
 
 Fig. 6. Five-Days-a-Week Group. Abscissa, Practice Periods. 
 
 Ordinate, Daily Score. Boys, R. H. , L. H. . Girls, 
 
 R. H. , L. H. . 
 
 was shown over the first and the final average was inferior. 
 There is a possibility that in this group the excitement 
 and overstrain often produced by preparations for Christ- 
 mas caused the decrease in efficiency during the trials for 
 the last week. 
 
 2-Days-a-Week Group 
 
 The average age for this group was six years, five months, 
 seven days for girls ; six years, two months, five days for 
 boys. Five boys and four girls were included in final 
 records. 
 
 The curve for girls shows gradual gain with varying 
 fluctuations. Again the boys show almost maximal effi- 
 ciency on the first day. With the right hand there is 
 gradual improvement through the fourth day with an irreg- 
 
46 
 
 MOTOR ABILITIES OF CHILDREN 
 
 TABLE IX 
 
 Showing the Daily Aver.^ges of the Two-Days-a-Week Group. 
 Tuesdays and Thursdays 
 
 
 Girls 
 
 Boys 
 
 Day 
 
 R. H. 
 
 L. H. 
 
 R. H. 
 
 L. H. 
 
 I 
 2 
 
 3 
 4 
 5 
 6 
 
 7 
 8 
 
 9 
 
 10 
 
 II 
 
 12 
 
 13 
 H 
 15 
 
 1.275 
 1.36 
 
 1-25 
 
 1.70 
 
 1.50 
 
 1.38 
 
 1.275 
 
 1-35 
 
 1-325 
 
 1.30 
 
 1.90 
 
 1.24 
 
 1-65 
 
 1.333 
 
 1.426 
 
 0.95 
 1.08 
 1.25 
 
 1.275 
 
 1. 10 
 
 1. 16 
 1.30 
 1.30 
 
 1. 00 
 
 1.30 
 1. 125 
 1. 180 
 1.625 
 I -033 
 1.475 
 
 I.616 
 
 1.683 
 
 1.733 
 
 1.75 
 
 1.466 
 
 1.533 
 
 1.586 
 
 1.58 
 
 1.46 
 
 1.48 
 
 1.30 
 
 1.60 
 
 I.616 
 
 1-683 
 
 1-366 
 
 1-483 
 1-05 
 1. 216 
 1.066 
 1.05 
 1.066 
 0.966 
 1. 16 
 1.18 
 1. 16 
 1. 10 
 1. 10 
 
 1. 116 
 
 1-25 
 
 1.483 
 
 Total 
 
 Av 
 
 21.263 
 1.417 
 0.144 
 
 18.153 
 
 I.2I0 
 0.134 
 
 23-432 
 1.562 
 0.102 
 
 17-446 
 
 1. 163 
 
 A. D 
 
 0.106 
 
 Difference between averages for R. H. 0.145 
 
 L. H. 0.047 
 Probable error of R. H. difference 0.0745 
 L. H. difference 0.0721 
 
 Fig. 7. Two-Days-a-Week Group. 
 Ordinate, Daily Score. Boys, R. H. ■ 
 R. H. , L. H. . 
 
 Abscissa, Practice Periods. 
 , L. H. . Girls, 
 
ACCURACY OF MOVEMENT 
 
 47 
 
 ular decline until the thirteenth day, when the score equals 
 that of initial records. The average results for both hands 
 are less than the initial scores. 
 
 There was seemingly no lack of interest on the part of 
 the boys but there is an indication that they did not put 
 forth their best efforts. There was sometimes a tendency 
 to attempt a fancy throw. 
 
 Once-a-Week Group 
 
 The average age of this group was seven years, four 
 months, eighteen days for girls; seven years, eight months, 
 five days for boys. The records of six girls and six boys 
 are reported. 
 
 TABLE X 
 
 Showing Daily Averages for Once-a-Week Group, Having 
 Twenty Throws with Each Hand in a P*ractice Period 
 
 
 Girls 
 
 Boys 
 
 
 R. H. 
 
 L.H. 
 
 R. H. 
 
 L. H. 
 
 I 
 
 2 
 
 3 
 4 
 5 
 6 
 
 7 
 
 1.483 
 
 1-333 
 1-366 
 
 1-875 
 1-537 
 1-36 
 1.61 
 
 1-233 
 1. 216 
 
 1-275 
 1.508 
 
 1-325 
 1.06 
 
 1-43 
 
 1.683 
 
 1-36 
 
 1-54 
 
 1-54 
 
 1.608 
 
 1-591 
 1-558 
 
 I.6I6 
 
 1-73 
 
 1-425 
 
 1.42 
 
 1-375 
 1.616 
 
 1-45 
 
 Total 
 
 Av 
 
 10.564 
 1-509 
 0.141 
 
 9-047 
 1.292 
 
 O.ll 
 
 10.881 
 
 1-554 
 0.063 
 
 10.632 
 I-519 
 0.115 
 
 A. D 
 
 Difference between averages for R. H. 0.045 
 
 L. H. 0.227 
 
 i-,. n. o.: 
 Probable error of R. H. difference 0.0574 
 L. H. difference 0.0612 
 
 A substantial but somewhat irregular improvement is 
 shown by the girls. The boys show the high initial efficiency 
 that has characterized the boys of the other groups, with but 
 slight evidence of improvement shown either by daily 
 averages or final average results. 
 
48 
 
 MOTOR ABILITIES OF CHILDREN 
 
 Once-in-Two-W eeks Group 
 
 For the girls of this group the average age was seven 
 years, one month, within a range of one year, one month; 
 
 Fig. 8. Once-a-Week Group. Abscissa, Practice Periods. Ordi- 
 nate, Daily Score. Boys, R. H. , L. H. . Girls, R. H. 
 
 , L.'H. . 
 
 for the boys the average age was six years, three months, 
 fifteen days, with a range of nine months. The records are 
 given for six girls and five boys. 
 
 With right hand there is a decrease in efficiency on second 
 day for boys, on second, third and fourth days for girls. 
 Then a gradual rise in curve shows slow but fairly regular 
 improvement. 
 
 The left hands show much more instability. The average 
 result for girls with left hand was less than score for first 
 day and the boys show very slight improvement. In this 
 group there was no subject who gave evidence of any desire 
 to use left hand, but rather a marked preference for right. 
 ( I ) Practice Effects. 
 
 The indications are that the limit of improvement has not 
 been reached. The rate is so lacking in uniformity and 
 varies so considerably for different groups that it is difficult 
 
ACCURACY OF MOVEMENT 
 
 49 
 
 TABLE XI 
 Showing Daily Averages for Once-in-Two-Weeks Group 
 
 
 Girls 
 
 Boys 
 
 Day 
 
 R. H. 
 
 L. H. 
 
 R. H. 
 
 L. H. 
 
 I 
 
 2 
 
 3 
 4 
 5 
 6 
 
 7 
 8 
 
 9 
 
 10 
 
 II 
 
 1.516 
 
 1-433 
 1-33 
 1-4 
 1.86 
 
 1-744 
 
 1.766 
 
 1.84 
 
 1.84 
 
 1-7 
 
 1-73 
 
 1-35 
 
 1-32 
 
 1. 216 
 
 I. 
 
 1.26 
 
 1-255 
 
 1-033 
 
 1-44 
 
 1.26 
 
 1. 188 
 
 1.366 
 
 1.4 
 1. 12 
 
 1.64 
 
 1-7 
 1.6 
 
 1-573 
 1.72 
 
 1-7 
 
 1-453 
 1.706 
 1.6 
 
 I.I 
 
 0.76 
 
 0.8 
 
 1.26 
 
 0-975 
 
 1-253 
 
 1-44 
 
 1-25 
 
 1.2 
 
 1-253 
 1.266 
 
 Total 
 
 Av 
 
 18.159 
 1-65 
 0.168 
 
 13.688 
 1.244 
 0.098 
 
 17.212 
 1-564 
 0.131 
 
 12.557 
 1. 141 
 0.28 
 
 A. D 
 
 Difference between averages for R. H. 0.086 
 
 L. H. 0.103 
 Probable error of difference for R. H. 0.084 
 
 L. H. 0.124 
 
 to get any satisfactory indication of acceleration or retarda- 
 tion of improvement. The irregularities may be accounted 
 
 ^^ -h 
 
 lYs 
 
 
 Fig. 9. Once-in-Two-Weeks Group. Abscissa, Practice Periods. 
 
 Ordinate, Daily Score. Boys, R. H. , L. H. . Girls, 
 
 R. H. , L. H. . 
 
50 
 
 MOTOR ABILITIES OF CHILDREN 
 
 for in part by differences in initial ability, in native capacity 
 to improve, and in cooperation of subject. 
 
 The amount of improvement as measured by comparison 
 of first day's score with final average is more clearly shown 
 in the following tables. The percentage columns represent 
 the percentage of initial efiiciency which the final average is. 
 
 TABLE XII 
 
 Showing the Relation between the Initial Scores and Final 
 Averages for Right Hands of All Groups 
 
 
 Girls 
 
 Boys 
 
 Group 
 
 zst 
 Day 
 
 Av. 
 
 % of Im- 
 provement 
 
 I St 
 
 Day 
 
 Av. 
 
 % of Im- 
 provement 
 
 5-Days-a-Week 
 
 1-5 
 
 1-275 
 1.483 
 1. 516 
 
 1.668 
 1.417 
 1-509 
 1-65 
 
 II. 2 
 II. I 
 
 1-75 
 8.83 
 
 2.033 
 I.616 
 1.683 
 
 1-4 
 
 1-573 
 1-562 
 
 1-554 
 1.564 
 
 -22.6 
 
 2-Days-a-Week 
 
 - 3-34 
 
 - 7.66 
 
 i-Day-a-Week 
 
 i-Day-in-2-VVeeks 
 
 11-7 
 
 TABLE XIII 
 
 Showing the Relation between the Initial Scores and Final 
 Averages for Left Hands of All Groups 
 
 
 Girls 
 
 Boys 
 
 Group 
 
 zst 
 Day 
 
 Av. 
 
 % of Im- 
 provement 
 
 ist 
 Day 
 
 Av. 
 
 % of Im- 
 provement 
 
 5-Days-a-VVeek 
 
 1-475 
 
 0.95 
 
 1-233 
 
 1-35 
 
 1-334 
 1. 21 
 1.292 
 1.244 
 
 - 9-4 
 27-3 
 
 4-78 
 7-85 
 
 1-3 
 1.483 
 I.616 
 I.I 
 
 1.62 
 1.163 
 
 I-519 
 1. 141 
 
 — 10.6 
 
 2-Days-a-VVeek 
 
 i-Day-a-Week 
 
 -21.3 
 - 6 
 
 l-Day-in-2-Weeks 
 
 3-72 
 
 The negative improvement shown in boys' records in- 
 validates somewhat conclusions for groups as a whole. The 
 once-in-two-weeks group shows greater improvement in 
 consideration of entire group. The girls in the two-days- 
 a-week group have less initial ability, hence greater percent- 
 age of improvement, if both hands are considered. 
 
 From the percentages of improvement given for girls, it 
 is evident that the short and frequent practice periods are 
 more valuable. The group having greatest number of 
 throws during a practice period with only one period a week 
 shows very little improvement. The co-operation of the 
 
ACCURACY OF MOVEMENT 5E 
 
 subject is so closely related to the improvement, for the de- 
 termination of the most economical distribution of the prac- 
 tice periods, it seems necessary to stimulate the subject suffi- 
 ciently for complete response to the task. Unless this can 
 be accomplished in frequent practice periods, then longer 
 intervals are more desirable. 
 
 (2) Index of Right-handedness. 
 
 By computing the percentage of efificiency of the left hand 
 to the right hand we obtain for the various groups the fol- 
 lowing indices: 
 
 Boys Girls 
 
 S-Days-a-Week 73 Per cent. 79 Per cent. 
 
 2-Days-a-Week 74 per cent. 85 per cent. 
 
 i-Day-a-Week 96 per cent. 85 per cent. 
 
 l-Day-in-2-Weeks 73 per cent. 75 per cent. 
 
 In the Once-a-week group the large percentage for boys 
 is due, doubtless, to the consistent superiority of left hand 
 in one subject. In same group two girls were slightly 
 superior with left hand in final average. In Two-days-a- 
 week group the left hand of one girl excelled her right hand 
 in the majority of throws. From j^% to 8o7o efficiency 
 with left hand is characteristic of groups having no left- 
 handed subjects. This can not be accepted as an absolute 
 index since right hand preceding left may condition it ta 
 some extent. 
 
 (3) Sex Differences. 
 
 According to the final averages the girls are superior with 
 both hands in the Five-days-a-week and Once-in-two-weeks 
 groups and for left hand in Two-days-a-week group. In 
 other cases the boys excel. 
 
 The probable errors show that the differences between 
 the averages for the sexes are insignificant except for left 
 hand of Five-days-a-week and Once-a-week groups. In the 
 former case the difference of 0.172 in favor of girls is 2.26 
 times its P. E. There was one girl in this group who 
 showed slight superiority with left hand. 
 
 In the second case the difference of 0.227 i" favor of boys 
 is 3.7 times its P. E. One of these boys was decidedly left- 
 
52 MOTOR ABILITIES OF CHILDREN 
 
 handed. Aside from these differences that the particular 
 cases might explain there is no distinct sex differentiation 
 evidenced by average results. 
 
 There is a noticeable sex difference in the course of im- 
 provement from day to day. In all groups of boys except 
 the Once-in-two-weeks group, the final average was less 
 than the initial score and the maximal score was made either 
 on first day or in early trials. The girls follow more closely 
 the usual course in learning and with the exception of two 
 left-hand averages, make better final averages than initial 
 records. Maximal efificiency is not attained until fourth day 
 or often much later in the series. 
 
 This suggests continued co-operation on part of girls 
 throughout the series, while the boys failed to respond with 
 the same interest during later trials. This is most notice- 
 able in the Five-days-a-week group. 
 
 The curve of boys who practiced only once in two weeks 
 resembles that of the girls. Maximal score is not made 
 until seventh day with right hand and on last day with 
 left hand. Here the longer period intervening between prac- 
 tice periods may cause the sustained interest and there is 
 gradual improvement. 
 
 It is also suggested that the initial performance of boys 
 represents more practice in this activity. Just how much it 
 is not possible to determine. Some questions were asked 
 as to previous motor activities but the answers were too 
 indirect to be satisfactory. Rubber balls for bouncing 
 seemed to be the chief kind with which the girls were ac- 
 quainted. In a few cases girls spoke of playing "catch" 
 with their young brothers. 
 
 There is certainly an indication that the emotional attitude 
 greatly affects progress in learning and that sex differentia- 
 tion is most distinct in the affective elements. 
 
VIII. PREFERENCE IN SIDE OF BODY USED 
 
 In both of the practice series in motor coordination 
 preference in hand used was very evident. At this age the 
 three types are readily recognized, the decidedly right- 
 handed, the practically ambidextrous, and those distinctly 
 preferring left hand. In the second class a given hand 
 is usually preferred for certain activities, such as writing 
 with one hand and throwing a ball with the other. It be- 
 comes an important problem of school management to de- 
 termine whether the left-handed person should be left alone 
 or ambidexterity cultivated. 
 
 Ballard (2) made three investigations into the effect of 
 interference with left-handedness, finding the percentage of 
 stammerers among the frankly left-handed to be 2%, the 
 same as among school children as a whole. But among the 
 left-handed who have been forced to write with right hand 
 this increases to 17%. He also reports a distinct difference 
 in intelligence between the two classes of left-handed chil- 
 dren, those upon whom ambidextral training has been forced 
 being clearly inferior, though coming as a rule from better 
 homes. 
 
 To investigate the preference in side of body used, a 
 number of children were examined in the school in which 
 the aiming test was conducted. 
 
 All the children of a first grade were taken to the gym- 
 nasium, and one child at a time, standing near center of hall, 
 was asked to kick a light football to another at the other 
 end of room, who in turn should kick it back. The foot 
 used was noted. Out of thirty-eight children, two boys and 
 one girl used the left foot. One of the boys. Otto, was 
 decidedly left-handed, writing with his left hand, and no 
 attempt had been made to force him to use right hand. The 
 other boy and the girl wrote with right hand and had a 
 
 53 
 
54 
 
 MOTOR ABILITIES OF CHILDREN 
 
 slight balance in favor of right hand in aiming test, though 
 on many days the left hand excelled. One left-handed girl, 
 Anna, among this group used her right foot. She also 
 writes with right hand. Her score in aiming was very low, 
 but left hand was slightly superior. 
 
 To discover any preference as to direction in turning, a 
 " soldier " game was used. Again we went to the gym- 
 nasium so as to have a large space with similar surroundings 
 on each side. There were windows on one side only, so the 
 back was turned to windows, thus having a blank wall in 
 front and at either side. Two straight lines were drawn 
 upon the floor in white crayon and the child was asked to 
 walk like a soldier from one to the other, turn, and walk 
 back again. This was repeated four times. The observer 
 stood about five feet directly behind the subject at starting. 
 No one was within his field of vision until after he had 
 turned. Sometimes there were only two and never more 
 than five children were in the gymnasium at one time. Re- 
 sults from fifty-five children between the ages of five and 
 eight years are as follows : 
 
 The number consistently turning to left was 30; to right 
 14. There were — 
 
 5 who turned to left 4 times ; to right i time. 
 
 2 who turned to left 3 times ; to right 2 times. 
 
 2 who turned to left 2 times ; to right 3 times. 
 
 2 who turned to left i time; to right 4 times. 
 
 Of the three decidedly left-handed subjects as determined 
 in aiming, two consistently tiu-ned to left, the boy, Otto, 
 mentioned in kicking of ball, and the girl, Anna. One boy, 
 William, who writes with left hand and made the best left- 
 handed score of entire group in aiming, his left hand failing 
 only once to excel his right, turned to left only twice out of 
 five times. 
 
 Since only 20% of number show inconsistency, it is evi- 
 dent that there is decided preference as to direction of turn. 
 The effect of training and imitation would have to be con- 
 sidered in a more complete analysis. Interference effects 
 
PREFERENCE IN SIDE OF BODY USED 55 
 
 might explain somewhat the lack of correlation between 
 preferred hand and preferred side in turning. The position 
 of thumb in clasping of hands, with fingers interlaced, is re- 
 ported by adults to be distinctly preferential. There is 
 scarcely a dissenting voice as to the awkwardness felt in 
 placing the other thumb than desired one on top. Among 
 the few adults tested, as a rule, the right-handed person puts 
 the left thumb on top and vice versa. This seems to give the 
 favored hand a more advantageous position for the clasp- 
 ing in which it takes the aggressive part. 
 
 Results from sixty- four children are given. These chil- 
 dren were not only asked to clasp hands and position of 
 thumbs noted as each one passed slowly by, but in a song 
 taught by their teacher they were required to sit with clasped 
 hands resting on desks. The observer passed along the 
 aisles during the singing of this song to note again the 
 manner of clasping. Position of thumb was same in each 
 case as in previous clasping. 
 
 28 — R. H. in writing — put R. thumb on top. 
 32 — R. H. in writing — put L. thumb on top. 
 
 3 — L. H. in wrifing — put R. thumb on top. 
 
 I — L. H. in writing — put L. thumb on top. 
 
 There is consistency and preference in form of clasping, but 
 the almost equal distribution of right-handed group shows 
 no direct correlation with favored hand in other activities. 
 
 The importance of the development of motor activities of 
 young children makes the question of motor methods and 
 of interference with use of preferred hand a vital one in 
 educational theory. While we need much more data as to 
 real effects of interference and the advisability of cultivat- 
 ing right-handedness, the data set forth certainly leads to the 
 conclusion that there is a marked preference as to side of 
 body used by an individual in his various activities, even 
 such as environmental compulsion or suggestion can not 
 explain. 
 
IX. GENERAL SUMMARY AND CONCLUSIONS 
 
 I. Rate OF Voluntary Movement 
 
 Previous research has shown marked increase in rate of 
 movement with increasing age. The results we have ob- 
 tained for young children compared with those established 
 for subjects of more advanced age accord with this finding. 
 
 There is gradual improvement due to practice but great 
 irregularity in early trials, the average rate being attained 
 by fourth or sixth day but maximal efficiency is not reached 
 until late in the series. 
 
 We seem justified in concluding that the initial trial, or 
 average of less than five trials, does not give a valid indica- 
 tion of actual ability, of fatigue effects, or of sex differences. 
 This corresponds to Kelly's (12) conclusion for children 
 from four to fourteen years old, that " there is no trust- 
 worthy correspondence between the work of the first ten 
 seconds and the child's real mental power so far as it may be 
 applied to any practical problem in life." 
 
 No direct correlation of fatigue and rate is found, nor 
 is there a distinct sex differentiation in loss by fatigue. The 
 index of fatigue is greater for use of hand not preferred. 
 
 There is a distinct difference between the sexes in ability 
 in tapping test, favoring the girls in this group, which has 
 far greater variation among girls with two subjects at each 
 extreme, while the boys cluster closely about the average. 
 This leads to no generalization concerning sex differences. 
 
 The index of right-handedness for girls is 78% ; for boys, 
 79%. Compared with Smedley's (19) 82% at age of nine 
 years, 89% at age of eighteen years, and with Wells' (21) 
 average index of 90% for adults, this indicates more pro- 
 nounced efficiency of right hand in childhood. 
 
 56 
 
general summary and conclusions 57 
 
 2. Steadiness of Motor Control 
 
 There is great variation in the outcome of this test, with 
 shifting superiority from one hand to the other. There is 
 evidence of but shght improvement from repetition of test. 
 
 The girls excelled with right hand, the boys with left 
 hand. The best individual score in each test was made by 
 a boy. 
 
 The index of right-handedness is lower than in tapping 
 and varies from test to test, so that it is not very reliable 
 as indicating efficiency of either hand. 
 
 3. Reaction Times 
 
 There is marked improvement due to practice in quick- 
 ness of response to visual stimulus. The simple reactions 
 preceding the discrimination were longer than the dis- 
 crimination, those following were shorter. 
 
 Premature responses are more frequent in simple reac- 
 tions, due, perhaps, to inhibitory effects of discrimination 
 reactions. 
 
 There is an increasingly shortened reaction time with 
 increasing age for subjects studied, but averages obtained 
 for children approximate much more closely those for adults 
 than is shown in results of other motor tests. The three 
 subjects from eight to ten years old have quicker reactions 
 than the seventeen-year-old subjects tested by Gilbert (8) 
 and McDonald (15). 
 
 We find less diflference between the simple and dis- 
 crimination reaction times than the results of these investi- 
 gators show. 
 
 4. Accuracy of Movement 
 
 The rate and amount of improvement in accuracy of 
 movement vary considerably for sexes and for groups with 
 different intervals between practice. 
 
 The aiming test is most reliable for indicating left-handed- 
 ness, the index varying from 73% to 80% for groups having 
 no left-handed subjects and reaching 96% for group having 
 a subject consistently left-handed. 
 
58 MOTOR ABILITIES OF CHILDREN 
 
 There is no distinct sex differentiation evidenced by 
 average results, except for left hand of two groups which 
 particular cases of superiority with left hand explain. 
 
 The sex difference in course of improvement from day to 
 day is so great that comparison of groups other than by 
 sexes is of little value. 
 
 The girls show a gradual improvement, with irregularities 
 in left-hand progress, and maximal efficiency is not attained 
 until fourth day or often much later in the series. 
 
 Short and frequent practice periods are more valuable 
 for girls. The group having greatest number of throws 
 during a practice period with only one practice a week shows 
 but little improvement. 
 
 The boys make higher initial scores than final averages in 
 all groups except the Once-in-two-weeks group. Maximal 
 score was made on first day or in early trials. 
 
 The boys of Once-in-two-weeks group have similar curve 
 to girls and maximal score is not made until seventh day 
 with right hand and fourth to last day with left hand. 
 
 This suggests better sustained interest of boys with longer 
 intervals between practice periods. 
 
 There is an indication of a distinct sex difference in the 
 emotional attitude towards motor activities, with more com- 
 plete response on part of boys in beginning showing negative 
 improvement; but a sustained interest on part of girls, 
 resulting in gradual progress. 
 
 5. Preference in Side of Body Used 
 
 There is a decided preference as to hand or foot used in 
 free motor activities : in direction of turning and in posi- 
 tion of fingers when hands are clasped. 
 
 There is no direct correlation of favored hand with 
 favored side used in other activities, but more consistency 
 in preference of left-handed group for left side than in 
 preference of right-handed group for right side. 
 
 The results for these groups could not be universally ap- 
 plied as representative of the motor abilities of children. 
 
GENERAL SUMMARY AND CONCLUSIONS 59 
 
 They certainly suggest the need of experimental evidence, 
 upon which to base the solution of practical educational 
 problems. 
 
 If educational guidance is to serve as a basis for vocational 
 guidance and such tests are to be applied for selective pur- 
 poses, beginnings having already been made in these lines, 
 the significance and reliability of such tests are most 
 important. 
 
BIBLIOGRAPHY 
 
 (1) Bagley, W. C. 
 
 On the Correlation of Mental and Motor Ability in 
 School Children. Amer. Journal Psy., vol. 12, 
 1 901, 193-205. 
 
 (2) Ballard, P. B. 
 
 Ambidexterity. Ed. Times, London, Feb., 1916. 
 
 (3) Boas, F. 
 
 The Growth of Children. Sci., 20: 1892, 351, 352. 
 
 (4) Bolton, T. L. 
 
 The Relation of Motor Power to Intelligence. Amer. 
 Jour. Psy., 2: 1895, 61 5> 631. 
 
 (5) Bryan, W. L. 
 
 On the Development of Voluntary Motor Ability. 
 Amer. Jour. Psy., Vol. 5, 1892, 123-204. 
 
 (6) Burt, C. and Moore, R. C. 
 
 The Mental Differences between the Sexes. Jour, 
 of Ex. Ped., Vol. I, 1911-12, 273-284 and 355- 
 388. 
 
 (7) Dresslar, F. B. 
 
 Some Influences Which Affect the Rapidity of Vol- 
 untary Movements. Amer. Jour. Psy., Vol. 4, 
 1892, 514-527- 
 
 (8) Gilbert, J. A. 
 
 Mental and Physical Development of School Chil- 
 dren, stud, from Yale Psy. Lab., Vol. 2, 1894, 
 40-100. 
 
 (9) Gilbert, J. A. 
 
 Researches upon School Children and College Stu- 
 dents. Univ. Iowa Stud. Psy., i : 1897, 1-39. 
 
 60 
 
BIBLIOGRAPHY 6 1 
 
 (10) Hancock, J. A. 
 
 A Preliminary Study of Motor Ability. Fed. Sem., 
 3: 1894, 9-29- 
 
 (11) Hollingworth, H. L. 
 
 The Influence of Cafifein on Mental and Motor Effi- 
 ciency. Arch. Psy., Vol. 22, 1912, N. Y. 
 
 (12) Kelly, R. L. 
 
 Psychophysical Tests of Normal and Abnormal Chil- 
 dren. Psy. Rev., Vol. 10, 1903. 
 
 (13) Leuba and Hyde. 
 
 An Experiment on Learning to Make Hand Move- 
 ments. Psy. Rev., Vol. 12, 351-369. 
 
 (14) Lashley, K. S. 
 
 Practice in Archery — not published. 
 
 (15) McDonald, Arthur. 
 
 Experimental Study of Children. Rep. Com. Ed., 
 1897-98, Chaps. XXI and XXII. 
 
 (16) Marsh, H. D. 
 
 The Diurnal Course of Efficiency. Col. Univ. Diss., 
 1906. 
 
 (17) Munn. 
 
 Curve of Learning Arch. Psy., No. 12, 37. 
 
 (18) Murphy, H. H. 
 
 Distribution of Practice Periods in Learning. Jour. 
 Ed. Psy., March, 1916. 
 
 (19) Smedley, F. W. 
 
 Report of Department of Child Study and Pedagogic 
 Investigation, Rep. Com. Ed., 1902, i: 1095-1138. 
 
 (20) Thompson, H. B. 
 
 The Mental Traits of Sex. Univ. Chicago, 1903. 
 
 (21) Wells, F. L. 
 
 Normal Performances in Tapping Test, before and 
 during Practice, with Special Reference to Fatigue 
 Phenomena. Amer. Jour. Psy., 19: 1908, 437- 
 483. 
 
62 MOTOR ABILITIES OF CHILDREN 
 
 (22) Wells, F. L. 
 
 Sex Differences in Tapping Test and Interpretation. 
 Amer. Jour. Psy., Vol. 20, 1909, 353-363. 
 
 (23) Woolley, H. T. and Fischer, C. R. 
 
 Mental and Physical Measurements of Working 
 Children. Psy. Mon., i. Vol. 18, 1914, 200-246. 
 
 (24) Whipple, G. M. 
 
 Manual of Physical and Mental Tests. 1914, Part I. 
 Baltimore, Warwick and York. 
 
VITA 
 
 Buford Jennette Johnson was born in Thomson, Georgia, 
 on the twenty-third of August, eighteen hundred and eighty. 
 She received her A.B. degree from LaGrange College in 
 eighteen hundred and ninety-five. The following year she 
 attended courses in Education at the Georgia State Normal 
 School. 
 
 After teaching in the Public Schools of Thomson and 
 Brunswick, Georgia, she became an Instructor in the de- 
 partment of Mathematics of LaGrange College, and later an 
 associate in Education and Psychology. 
 
 In January, nineteen hundred and fourteen she entered 
 The Johns Hopkins University, registering for major work 
 in Education, with Psychology and Mathematics as subor- 
 dinate subjects. She held a Hopkins scholarship for the 
 following year and received her Master's degree in June, 
 nineteen hundred and fifteen. 
 
 The George Peabody Scholarship in Education was 
 awarded to her for the scholastic year nineteen hundred and 
 fifteen-sixteen. 
 
 63 
 
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