The Relation of General Intelligence, Motor Adaptability, and Motor Learning to Success in Dental Technical Courses
- Author:
Richard S. Schultz
The Psychological Corporation, New YorTc City
Introduction
Dentistry involves a marked degree of “motor” or “mechanical” skill1 as well as a broad knowledge of the Medical Sciences. In actual practice, the dentist spends the greater part of his time working with his ‘’ hands.’’ An analysis of the dental curriculum reveals that 57.4 per cent of the student’s training involves manipulative performances.2 A statement and definition of the abilities and qualifications which are most important, and the extent to which they contribute to success in dental training and in actual practice are the subject of an earlier paper by the author, published in the Psychological Clinic.3- 4
The purpose of the present paper is to present data on the relation of general intelligence, ability to solve a motor problem and to learn a motor problem, respectively, to success in Dental Technical Courses. Subjects The investigation included 90 men, the entire second year class, in the School of Dentistry, University of Pennsylvania. The class * The writer wishes to acknowledge his indebtedness to Dr Charles R. Turner, Dean of the Dental School; and to Professors Edwin B. Twitmyer, Samuel W. Fernberger, and Morris S. Viteles, Department of Psychology, of the University of Pennsylvania.
1 Paterson, D. G., Elliott, R. M., et al., Minnesota mechanical ability tests, 1930, 5-11, 136 ff. “A scale was developed and used for grading occupations according to the judged amount of mechanical ability involved.” Dentistry received a rating of 4.55 S.D., and is, therefore, considered as an occupation involving a high degree of mechanical ability. 2 The Carnegie Foundation for the Advancement of Teaching, Dental Education in the U. S. and Canada, Bulletin 19, 1926. 3 This study is part of a comprehensive program of research which has been outlined by the writer.
4 Schultz, R. S., A Review on the Measurement and Description of Qualifications for Dentistry and Dental Training, Psychol. Clin., 1932, 21, 172-182. was selected because it represented a relatively homogeneous group. These students have received intensive technical training, preparatory to undertaking practical clinical work with patients. They averaged about 22% years of age, with a range from 20 to 28 years.
Procedure
The Miles Two-Story Duplicate Maze 5 was selected as a device for obtaining a measure of the ability to solve a motor problem as well as of the ability to learn a motor problem. This apparatus has the advantage of presenting a task involving the coordination of two “hands” combined with the use of the visual, tactile, and kinaesthetic senses. It consists of two identical maze patterns, one mounted directly above the other, on a wooden box with two open sides. The task requires the movement of a stylus through a stationary visible top pattern by one hand, while at the same time a pencil is moved through a screened bottom pattern by the other hand.6’7
First an attempt was made to obtain a measure of the various abilities and traits that may be evoked in adaptation to a relatively novel motor situation. Problems of varying difficulty in motor adaptation were arranged by rotating the bottom maze, with reference to the top maze, to five successive positions (0?, 180?, 90?, 180? reverse, 90? reverse). Each position was to be traced as quickly as possible.
After this adaptability task, one of the above problems (180? reverse position) was given as a learning task. The general instructions were to learn to trace through the maze pattern as quickly as possible without error.
The Psychological Examination, American Council on Educa5 Miles, W. R., The Two-story Duplicate Maze, J. Exper. Psychol., 1927, 10, 365-377.
6 Tlie formation of habits from a visual plan is one of the most important aspects of the dental student’s practical learning. Much of what he learns, in laboratory demonstrations, lectures, personal instruction in practical work, etc., must be reproduced some time later. There is only a limited opportunity to perform actual movements or operations while receiving instruction. He must, therefore, depend on memory, models, and possibly imagery. In the course in Operative Dentistry the student is trained to explore and to make minutely controlled movements in unseen or limited visual fields, with the dental mirror as an accessory.
7 For detailed description of procedure and method of scoring see Schultz, E. S., The Relation of Maze Adaptability, Maze Learning, and General Intelligence, Amer. J. Psychol., 1932, 44, 249-262. tion,8 was used to obtain a measure of general intelligence. It was administered, before any maze tests were given, as a group examination.
Results
The significance of the scores on the intelligence test and the maze tests is evaluated by comparisons with rank order ratings and grades in dental technical courses, on the basis of which the students were divided into Best, Average, and Poor groups.9 Test scores are distributed according to this classification. The measures of success include eight technical criteria. Three are based on second year technical courses: (1) a General rank order rating of ability, the average of the ratings by three instructors; (2) an Average Operative rank order rating, the average of the ratings by two instructors in operative technics; (3) a Prosthetic Technic rank order rating, estimate of one instructor. The final per cent marks in the technical courses for the first and second years yield five additional criteria.
The criteria are numbered in the tables and figures as follows: I. General average rank order II. Average operative rank order III. Prosthetic rank order IV. Average technical grade second year V. Operative grade second year VI. Prosthetic grade second year VII. Prosthetic grade first year VIII. Operative grade first year These data are analyzed by a study of how well the tests discriminate the Best, Average, and Poor groups of technical ability. Coefficients of correlation are also computed to obtain an index of the degree of correspondence between test scores and achievement in technical courses.
1. General Intelligence and Achievement in Technical Courses In Fig. 1 and Table 1 the average score on the intelligence test for the Poor group is below the average for the Best and Average 8 Thurstone, L. L., and Thurstone, T. 6., The 1929 Psychological Examination, Educ. Record, 1930, 11, 101 ff. ? Approximately 68 per cent of the cases are included in the average group, and the remaining cases are divided equally between the two other groups. This division is based on the assumption that the abilities under consideration are distributed to follow the general trend of the normal probability curve.
Table 1 Comparison of Intelligence Test Scores fob Best, Average, and Poor Groups of Achievement in Dental Technical Courses Criterion Best No. Av. Median Range Average No. Av. Median Range Poor No. Av. Median Range I 13 I I 13 II I 15 I V 16 V 15 V I 15 VI I 19 VII I 15 197 210 195 196 199 184 197 190 200 219 196 198 199 172 209 199 73-271 135-271 73-271 73-271 127-271 73-273 73-271 126-260 58 59 59 56 58 57 51 58 189 188 185 192 188 196 185 188 189 189 188 193 192 203 186 186 57-299 57-299 57-299 57-299 57-299 57-299 57-299 57-299 14 13 15 16 15 16 20 17 183 175 190 164 174 160 181 181 168 168 191 166 166 161 168 184 88-298 109-242 75-299 96-234 109-243 96-209 88-299 88-263
groups, and for tlie entire group of 90 cases. The differences are most pronounced when the Poor group is compared with the Best group. Coefficients of correlation (Table 2) between intelligence test scores and achievement in technical courses are low and statistically unreliable. The intelligence test appears to have most value in differentiating general ability in technical courses, as signified by the criterion?average technical grade second year.
Table 2 Correlation of Scores in Tests with Measures of Achievement (Criteria) in Dental Technical Courses No. Criterion General Intelligence 85-90 P.E.r Maze Adaptability 52-55 P.E.r Maze Learning 35-37 P.E.r I… II… III. . IV.. V… VI.. VII. VIII. +.104 + .208 -.031 + .227 +.161 +.189 +.130 +.063 .073 .070 .071 .068 .070 .070 .070 .071 .297 .289 .294 .318 .279 .279 .372 .247 .086 .086 .083 .083 .085 .084 .078 .086 -.094 (-.246) -.139 (-.203) -.136 (-.310) -.164 (-.425) +.013 (-.120) -.231 (-.466) -.333 (-.371) -.204 (-.454) .112 (.109) .111 (.110) .111 (.103) .110 (.090) .112 (.111) .107 (.087) .100 (.098) .108 (.091) ‘er+7e ? ? ? ? Best *? ? ? Atera^e ~ P??r ~_mj_ I II III IV V VI VII VIII
Criterion
Fig. 1. Comparison of Average Intelligence Test Score for Best, Average, and Poor Groups of Achievement in Dental Technical Courses 2. Motor Adaptability and Achievement in Technical Courses The data on the maze adaptability test (Figure 2, Table 3) reveal that the Poor group in technical achievement is, in general, below the average score for the Best and Average groups, and for the entire group.10 The largest and most consistent differences in average score appear when the Best and Average groups are compared, respectively, with the Poor group. In Table 4 the per cent values show that in the Poor group approximately two out of three cases tend to fail in one or more adaptability problems; while in the Best and Average groups a failure occurs in about one out of three cases. A further analysis of these results reveals a low consistent tendency favoring a higher average and median rank order rating and grade in technical courses for the successful group both in maze adaptability and maze learning when compared with the failure group.11
i? Since 38 per cent of the 89 subjects (one withdrew from school) failed in one or more adaptability problems, it seemed advisable to treat the results in a scoring method which would include the failures. A total score was first computed so that all five adaptability problems would have a relatively equal weight. (This total weighted score was used in the correlations.) The total weighted score was then subtracted from 4500 (maximum time in seconds for all five problems). Group comparisons are based on these scores. They are to be interpreted as higher score equals better score. ii An adaptability problem not solved in 900 seconds was recorded as a failure. In learning a failure was defined as inability to trace the maze pattern for two successive trials without any errors. Most subjects completed the maze tests in about 1 hour; the time varied from 40 minutes to 3 hours. 4000 3900 3800 3700 3600 3500 a; 3400 | 3300 m 3200 3100 trt/rc (“CMP 36 Sf . I II III IV V VI VII VIII Criterion Fig. 2. Comparison of Average Maze Adaptability Test Score for Best, Average, and Poor Groups of Achievement in Dental Technical Courses
Table 3 COMPARISON OF MAZE ADAPTABILITY TEST SCORES FOR BEST, AVERAGE, AND POOR GROUPS OF ACHIEVEMENT IN DENTAL Technical Courses Criterion Best No. Av, Median Range Average No. Av. Median Range Poor No. Av. Median Range I… , II… III.. IV.. V. .. VI.. VII. VIII. 13 13 15 16 15 15 19 15 3579 3642 3847 3860 3872 3825 3931 3895 4218 4239 4239 4215 4239 4116 4239 4239 770-4347 770-4313 2532-4347 2162-4347 2162-4378 2532-4347 2162-4398 2162-4398 58 59 59 56 58 57 50 57 3763 3773 3676 3818 3768 3774 3685 3642 4103 4111 4097 4156 4111 4132 4083 4074 1625-4375 875-4375 770-4375 770-4375 770-4375 770-4375 770-4375 770-4375 14 13 15 16 15 16 20 15 3460 3313 3632 3187 3237 3267 3566 3732 3952 3452 4134 3370 3452 3370 4116 4191 803-4359 803-4359 1440-4334 803-4295 803-4359 803-4378 803-4286 1440-4295 RELATION OF INTELLIGENCE TO SUCCESS 233 Table 4 Comparison op Per Cent Failures in One or More Maze Adaptability Problems for Best, Average, and Poor Groups of Achievement in Dental Technical Courses Criterion II III IV VI VII VIII Best… . Average. Poor… 38 38 50 31 37 62 40 37 40 38 32 62 33 36 53 40 32 62 32 40 40 27 42 35
The coefficients of correlation, between maze adaptability scores 12 and measures of technical achievement (Table 2) are higher, thus showing better agreement than those obtained with the intelligence test. These correlations indicate a tendency for a lower (better) time score in maze adaptability to be associated with higher achievement in technical courses and vice versa. The most statistically reliable coefficients occur with average technical grade second year and prosthetic grade first year. These two measures of technical achievement are most clearly differentiated in the above group comparisons.
3. Motor Learning and Achievement in Technical Courses No significant relationship appears between ability to learn a maze and achievement in technical courses.13 However, when two cases which fell beyond the extreme upper range of scores are eliminated, there is a marked increase in the magnitude of the coefficients of correlation, as shown by the figures in parenthesis in Table 2. The largest and most reliable coefficients are then found with average technical grade second year, prosthetic grade first and second years, and operative grade first year.
General Conclusions
The tests in this investigation have shown, in general, most value in differentiating extreme degrees of low and high ability in dental technical courses. In this respect, the findings are to be regarded as most positive.
General intelligence appears to have less significance in achieve12 The correlations are based on cases successful in all five problems. 13 Thirty-seven cases, successful in both adaptability (all five problems) and learning, were especially isolated in order to obtain a group for which the conditions of relative and complete maze performance are comparatively uniform. ment in dental technical courses than maze adaptability. The results on maze adaptability reveal that there is a low significant relationship between ability in a task involving quick and effective adjustment to a relatively novel motor situation and achievement in dental technical courses. Maze learning ability appears to be significantly associated with achievement in dental technical courses, when two extreme cases are eliminated.
The results of this investigation and related observations suggest that additional experimentation with the Miles two-story duplicate maze test may further reveal its specific value in a battery of special aptitude tests for dentistry.
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