Scoring. Three of the four problems must be solved correctly within the half-minute allotted to each.
Remarks. Success depends, in the first place, upon ability to comprehend the statement of the problem and to hold its conditions in mind. Subjects much below the 12-year level of intelligence are often unable to do this.
Granting that the problem has been comprehended, success seems to depend chiefly upon the facility with which the constructive imagination manipulates concrete visual imagery. In this respect it resembles the problem of reversing the hands of a clock. With some subjects, however, verbal imagery alone is operative. Tactual imagery would, of course, serve the purpose as well.
This is as good a place as any to emphasize the fact that the introspective study of mental imagery has little to contribute to the measurement of intelligence. Intelligence tests are concerned with the total result of a thought process, rather than with the imagery supports of that process. Thought may be carried on almost equally well by various kinds of imagery. As Galton showed, a person can be taught to carry on arithmetical processes by the use of smell imagery. The kind of imagery employed is the product of slight, innate preferences complicated by the more or less accidental effects of habit.
We may say that imagery is to thinking what scaffolding is to architecture. The important thing is the completed building rather than the nature of the scaffolding employed in erecting it. No one thinks of blaming the ill construction of a building upon the kind of scaffolding used, for if the architect and builder are competent satisfactory scaffolding will be found. Just as little are deficiencies or peculiarities of imagery the real cause of low-order intelligence. We cannot increase intelligence by formal drill in the use of supposedly important kinds of mental imagery, any more than we can transform a plain carpenter into a Michael Angelo by instructing him in the use of scaffolding materials such as were employed in the construction of St. Peter’s Cathedral.
This test is of our own invention and has been brought to its present form only after a good deal of preliminary experimentation. It correlates fairly well with mental age as determined by the scale as a whole. It was passed by 55 per cent of high-school pupils and by 65 per cent of unschooled business men. Success in it is thus seen not to depend upon schooling.
Average adult, 5: repeating six digits reversed
The series used are: 4–7–1–9–5–2; 5–8–3–2–9–4; and 7–5–2–6–3–8.
Procedure and Scoring, as in [year VII, alternative 2].
Remarks. The test is passed by approximately half of “average adults” and by three fourths of “superior adults.” It shows no effect of schooling, the uneducated business men even surpassing our high-school students.