The Measurement of Intelligence. Lewis M. Terman

Distribution of I Q’s of 905 Unselected Children, 5–14 Years of Age 66

      3 Median I Q of 457 Boys and 448 Girls, for the Ages 5–14 Years 69

      4 Diamond drawn by R. W.; Age 13–10; Mental Age 7–6 82

      5 Writing from Dictation. R. M., Age 15; Mental Age 9 83

      6 Ball and Field Test. I. M., Age 14–2; Mental Age 9 84

      7 Diamond drawn by A. W. 85

      8 Drawing Designs from Memory. H. S., Age 11; Mental Age 8–3 86

      9 Ball and Field Test. S. F., Age 17; Mental Age 11–6 88

      10 Writing from Dictation. C. P., Age 10–2; Mental Age 7–11 90

      11 Ball and Field Test. M. P., Age 14; Mental Age 10–8 91

      12 Ball and Field Test. R. G., Age 13–5; Mental Age 10–6 93

      13 Ball and Field Test. E. B., Age 7–9; I Q 130 98

      14 Ball and Field Test. F. McA., Age 10–3; Mental Age 14–6 100

      15 Drawing Designs from Memory. E. M., Age 6–11; Mental Age 10, I Q 145 101

      16 Ball and Field Test. B. F., Age 7–8; Mental Age 12–4; I Q 160 102

      17 Healy and Fernald Construction Puzzle 279

THE MEASUREMENT OF INTELLIGENCE

       PART I

       PROBLEMS AND RESULTS

       Table of Contents

THE MEASUREMENT OF

       INTELLIGENCE

       Table of Contents

CHAPTER I

       THE USES OF INTELLIGENCE TESTS

       Table of Contents

Intelligence tests of retarded school children.

       Table of Contents

      Numerous studies of the age-grade progress of school children have afforded convincing evidence of the magnitude and seriousness of the retardation problem. Statistics collected in hundreds of cities in the United States show that between a third and a half of the school children fail to progress through the grades at the expected rate; that from 10 to 15 per cent are retarded two years or more; and that from 5 to 8 per cent are retarded at least three years. More than 10 per cent of the $400,000,000 annually expended in the United States for school instruction is devoted to re-teaching children what they have already been taught but have failed to learn.

      The first efforts at reform which resulted from these findings were based on the supposition that the evils which had been discovered could be remedied by the individualizing of instruction, by improved methods of promotion, by increased attention to children’s health, and by other reforms in school administration. Although reforms along these lines have been productive of much good, they have nevertheless been in a measure disappointing. The trouble was, they were too often based upon the assumption that under the right conditions all children would be equally, or almost equally, capable of making satisfactory school progress. Psychological studies of school children by means of standardized intelligence tests have shown that this supposition is not in accord with the facts. It has been found that children do not fall into two well-defined groups, the “feeble-minded” and the “normal.” Instead, there are many grades of intelligence, ranging from idiocy on the one hand to genius on the other. Among those classed as normal, vast individual differences have been found to exist in original mental endowment, differences which affect profoundly the capacity to profit from school instruction.

      We are beginning to realize that the school must take into account, more seriously than it has yet done, the existence and significance of these differences in endowment. Instead of wasting energy in the vain attempt to hold mentally slow and defective children up to a level of progress which is normal to the average child, it will be wiser to take account of the inequalities of children in original endowment and to differentiate the course of study in such a way that each child will be allowed to progress at the rate which is normal to him, whether that rate be rapid or slow.

      While we cannot hold all children to the same standard of school progress, we can at least prevent the kind of retardation which involves failure and the repetition of a school grade. It is well enough recognized that children do not enter with very much zest upon school work in which they have once failed. Failure crushes self-confidence and destroys the spirit of work. It is a sad fact that a large proportion of children in the schools are acquiring the habit of failure. The remedy, of course, is to measure out the work for each child in proportion to his mental ability.

      Before an engineer constructs a railroad bridge or trestle, he studies the materials to be used, and learns by means of tests exactly the amount of strain per unit of size his materials will be able to withstand. He does not work empirically, and count upon patching up the mistakes which may later appear under the stress of actual use. The educational engineer should emulate this example. Tests and forethought must take the place of failure and patchwork. Our efforts have been too long directed by “trial and error.” It is time to leave off guessing and to acquire a scientific knowledge of the material with which we have to deal. When instruction must be repeated, it means that the school, as well as the pupil, has failed.

      Every child who fails in his school work or is in danger of failing should be given a mental examination. The examination takes less than one hour, and the result will contribute more to a real understanding of the case than anything else that could be done. It is necessary to determine whether a given child is unsuccessful in school because of poor native ability, or because of poor instruction, lack of interest, or some other removable cause.

      It is not sufficient to establish any number of special classes, if they are to be made the dumping-ground for all kinds of troublesome cases—the feeble-minded, the physically defective, the merely backward, the truants, the incorrigibles, etc. Without scientific diagnosis and classification of these children the educational work of the special class must blunder along in the dark. In such diagnosis and classification our main reliance must always be in mental tests, properly used and properly interpreted.

Intelligence tests of the feeble-minded.

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      Thus far intelligence tests have found their chief application in the identification and grading of the feeble-minded. Their value for this purpose is twofold. In the first place, it is necessary to ascertain the degree of defect before it is possible to decide intelligently upon either the content or the method of instruction suited to the training of the backward child. In the second place, intelligence tests are rapidly extending our conception of “feeble-mindedness” to include milder degrees of defect than have generally been associated with this term. The earlier methods of diagnosis