Among the somewhat less satisfactory tests are the following: repeating digits (direct order), naming coins, distinguishing forenoon and afternoon, defining in terms of use, drawing designs from memory, and æsthetic comparison. Binet’s “line suggestion” test correlated so little with intelligence that it had to be thrown out. The same was also true of two of the new tests which we had added to the series for try-out.
Tests showing a medium correlation with the scale as a whole include arranging weights, executing three commissions, naming colors, giving number of fingers, describing pictures, naming the months, making change, giving superior definitions, finding similarities, reading for memories, reversing hands of clock, defining abstract words, problems of fact, bow-knot, induction test, and comprehension questions.
A test which makes a good showing on this criterion of agreement with the scale as a whole becomes immune to theoretical criticisms. Whatever it appears to be from mere inspection, it is a real measure of intelligence. Henceforth it stands or falls with the scale as a whole.
The reader will understand, of course, that no single test used alone will determine accurately the general level of intelligence. A great many tests are required; and for two reasons: (1) because intelligence has many aspects; and (2) in order to overcome the accidental influences of training or environment. If many tests are used no one of them need show more than a moderately high correlation with the scale as a whole. As stated by Binet, “Let the tests be rough, if there are only enough of them.”
FOOTNOTES:
[19] See p. [52] ff. for method used to avoid accidental selection of subjects for the Stanford investigation.
[20] See [Chapter VI] for discussion of the significance of various I Q’s.
[22] For discussion of the supposed advantages of the “point-scale method,” see Yerkes and Bridges: A New Point Scale for Measuring Mental Ability. (Warwick and York, 1915.)
[23] It will be remembered that this series of tests did not follow up and test those who had been promoted to high school.