Story of Psychology - Morton Hunt [151]
At Stanford University he spent several years in the education department and then became head of the psychology department. In the course of a long and distinguished career he made the department a leading graduate and research center, conducted a respected long-term study of gifted children, and carried out a classic study of the psychological factors in marital happiness. But his main claim to fame, major contribution to psychology, and chief influence on American life was the Stanford-Binet scale.
Terman’s experience with the Binet-Simon scale, even in its 1911 revision, had led him to believe that it had too few tests at the upper mental levels, that many tests at both the low end and the high end were misplaced in the sequence, and that the correct procedures for giving and interpreting the test were inadequately defined. With the help of eight collaborators and many public school teachers, he tried out the old tests and forty new ones (twenty-seven of which, and nine others taken from other sources, were added to the final series) on seventeen hundred normal children, two hundred retarded and superior children, and over four hundred adults. In its final form, the Stanford-Binet scale comprised ninety tests; those applicable to children between the ages of three and five took about half an hour to administer, and those to older groups longer and longer; the adult level required from an hour to an hour and a half.46
How well children of any age did with each test was compared with how well they did on others; those tests which were too easy for children of a given age were shifted to an earlier place in the sequence, those which were too hard, to a later one. To balance the scale, additional tests were added at the lower and upper ends. The results of the testing were compared with teachers’ estimates of the same children’s intelligence by the Pearsonian correlation method; the overall correlation was .48, or moderately high, thereby validating the scale. The correlation would have been still higher had not teachers, in estimating childrens’ intelligence, sometimes failed to take into account that some of the children were either younger or older than most of their classmates.
The most valuable aspect of the revision was that the entire scale was far more thoroughly “standardized” than Binet-Simon or Goddard-Binet-Simon; that is, the scores were based on results achieved with a large standard sample of normal, retarded, and superior children and adults. On this basis, a child or adult who scored 100 was average; one who scored 130 or better was more intelligent than 99 percent of the population at large; and one who scored 70 or below was less intelligent than 99 percent of the population. Terman classified the grades of intelligence as follows:
140 and up ………. “Near” genius or genius
120–140 ………… Very superior intelligence
110–120 ………… Superior intelligence
90–110 ………… Normal or average intelligence
80–90 ……………… Dullness, rarely classifiable as feeble-mindedness
70–80 ……………… Border-line deficiency, sometimes classifiable as dullness, often as feeble-mindedness
Below 70 ………… Definite feeble-mindedness
Terman, a mild-mannered and kindly man, voiced benign hopes for the use of the new scale:
When we have learned the lessons which intelligence tests have to teach, we shall no longer blame mentally defective workmen for their industrial inefficiency, punish weak-minded children because of their inability to learn, or imprison and hang mentally defective criminals because they lacked the intelligence to appreciate the ordinary codes of social conduct.47
If the Stanford-Binet did not exactly make those sentiments a reality, neither did