In this experiment the subject may fail in any one of the three requirements of the test or in all of them. (1) He may not comprehend the instructions and so be unable to set the goal. (2) Though understanding what is expected of him, he may adopt an absurd method of carrying out the task. Or (3) he may lose sight of the end and begin to play with the blocks, stacking them on top of one another, building trains, tossing them about, etc. Sometimes the guiding idea is not completely lost, but is weakened or rendered only partially operative. In such a case the subject may compare some of the blocks carefully, place others without trying them at all, but continue in his half-rational, half-irrational procedure until all the blocks have been arranged.
It is essential, therefore, to supplement the mere record of success or failure by jotting down a brief but accurate description of the performance. Note any hesitation or inability to grasp the instructions. Note especially any absurd procedure, such as placing all the blocks without hefting any of them, comparing only some of them, holding them up and shaking them, hefting two at once in the same hand, etc. The ideal method, of course, is to try all the blocks carefully before placing any of them, then to make a tentative arrangement, and finally, to correct this tentative arrangement by means of individual comparisons. A slight departure from this method does not always bring failure, but it renders success less probable. As a rule it is only the very intelligent children of 10 years who think to test out their first arrangement by making a final and additional trial of each block in turn. Contrary to what might be supposed, success is slightly favored by hefting the blocks successively with one hand rather than by taking one in each hand for simultaneous comparison, but as the child cannot be expected to know this, we must regard the two methods as equally logical.
The test of arranging weights has met universal praise. Its special advantage is that it tests the subject’s intelligence in the manipulation of things rather than his capacity for dealing with abstractions. It tests his ability to do something rather than his ability to express himself in language. It throws light upon certain factors of motor adaptation and practical judgment which play a great part in the everyday life of the average human being. It depends as little upon school, perhaps, as any other test of the scale, and it is readily usable with children of all nations without danger of being materially altered in translation Moreover, it is always an interesting test for the child. Bobertag goes so far as to say that any 8- or 9-year child who passes this test cannot possibly be feeble-minded. This may be true; but the converse is hardly the case; that is, the failure of older children is by no means certain proof of mental retardation. The same observation, however, applies equally well to many other of the Binet tests, some of which correlate more closely with true mental age than this one. A rather considerable fraction of normal 12-year-olds fail on it, and it is in fact somewhat less dependable than certain other tests if we wish to differentiate between 9-year and 11-year intelligence. But it is a test we could ill afford to eliminate.[63]
IX, 3. Making change
Procedure. Ask the following questions in the order here given:—
- “If I were to buy 4 cents worth of candy and should give the storekeeper 10 cents, how much money would I get back?”
- “If I bought 13 cents worth and gave the storekeeper 15 cents, how much would I get back?”
- “If I bought 4 cents worth and gave the storekeeper 25 cents, how much would I get back?”
Coins are not used, and the subject is not allowed the help of pencil and paper. If the subject forgets the statement of the problem, it is permissible to repeat it once, but only once. The response should be made in ten or fifteen seconds for each problem.
Scoring, The test is passed if two out of three problems are answered correctly in the allotted time. In case two answers are given to a problem, we follow the usual rule of counting the second and ignoring the first.
Remarks. Problems of this nature, when thoroughly standardized, are extremely valuable as tests of intelligence. The difficulty of the test, as we have used it, does not lie in the subtraction of 4 from 10, 12 from 15, etc. Such subtractions, when given as problems in subtraction, are readily solved by practically all normal 8-year-olds who have attended school as much as two years. The problems of the test have a twofold difficulty: (1) The statement of the problem must be comprehended and held in mind until the solution has been arrived at; (2) the problem is so stated that the subject must himself select the fundamental operation which applies. The latter difficulty is somewhat the greater of the two, addition sometimes being employed instead of subtraction.
It is just such difficulties as this that prove so perplexing to the feeble-minded. High-grade defectives, although they require more than the usual amount of drill and are likely to make occasional errors, are nevertheless capable of learning to add, subtract, multiply, and divide fairly well. Their main trouble comes in deciding which of these operations a given problem calls for. They can master routine, but as regards initiative, judgment, and power to reason they are little educable. The psychology and pedagogy of mental deficiency is epitomized in this statement.