Library Collections: Document: Full Text

II.

BECAUSE the results are expressed in numbers, it is easy to make the mistake of thinking that the intelligence test is a measure like a foot rule or a pair of scales. It is, of course, a quite different sort of measure. For length and weight are qualities which men have learned how to isolate no matter whether they are found in an army of soldiers, a heap of bricks, or a collection of chlorine molecules. Provided the footrule and the scales agree with the arbitrarily accepted standard foot and standard pound in the Bureau of Standards at Washington they can be used with confidence. But "intelligence" is not an abstraction like length and weight; it is an exceedingly complicated notion which nobody has as yet succeeded in defining.

When we measure the weight of a schoolchild we mean a very definite thing. We mean that if you put the child on one side of an evenly balanced scale, you will have to put a certain number of standard pounds in the other scale in order to cancel the pull of the child's body towards the centre of the earth. But when you come to measure intelligence you have nothing like this to guide you. You know in a general way that intelligence is the capacity to deal successfully with the probes that confront human beings, but if you try to say what those problems are, or what you mean by "dealing" with them, or by "success," you will soon lose yourself in a fog of controversy. This fundamental difficulty confronts the intelligence tester at all times. The way in which he deals with it is the most important thing to understand about the intelligence test, for otherwise you arc certain to misinterpret the results.

The intelligence tester starts with no clear idea of what intelligence means. He then proceeds by drawing upon his common sense and experience to imagine the different kinds of problems men face which might in a general way be said to call for the exercise of intelligence. But these problems are much too complicated and too vague to be reproduced in the classroom. The intelligence tester cannot confront each child with the thousand and one situations arising in a home, a workshop, a farm, an office or in politics, that call for the exercise of those capacities which in a summary fashion we call intelligence. He proceeds, therefore, to guess at the more abstract mental abilities which come into play again and again. By this rough process the intelligence tester gradually makes up his mind that situations in real life call for memory, definition, ingenuity and so on.

He then invents puzzles which can be employed quickly and with little apparatus, that will according to his best guess test memory, ingenuity, definition and the rest. He gives these puzzles to a mixed group of children and sees how children of different ages answer them. Whenever he finds a puzzle that, say, sixty percent of twelve year old children can do, and twenty percent of the eleven year olds, he adopts that test for the twelve year olds. By a great deal of fitting he gradually works out a series of problems for each age group which sixty percent of his children can pass, twenty percent cannot pass and, say, twenty percent of the children one year younger can also pass. By this method he has arrived under the Stanford-Binet system at a conclusion of this sort: Sixty percent of children twelve years old should be able to define three out of the five words: pity, revenge, charity, envy, justice. According to Professor Terman's instructions, a child passes this test if he says that "pity" is "to be sorry for some one"; the child fails if he says "to help" or "mercy." A correct definition of "justice" is as follows: "It's what you get when you go to court"; an incorrect definition is "to be honest."

A mental test, then, is established in this way: The tester himself guesses at a large number of tests which he hopes and believes are tests of intelligence. Among these tests those finally are adopted by him which sixty percent of the children under his observation can pass. The children whom the tester is studying select his tests.

There are, consequently, two uncertain elements. The first is whether the tests really test intelligence. The second is whether the children under observation are a large enough group to be typical. The answer to the first question -- whether the tests are tests of intelligence -- can be determined only by seeing whether the results agree with other tests of intelligence, whatever they may be. The answer to the second question can be had only by making a very much larger number of observations than have yet been made. We know that the largest test made, the army examinations, showed enormous error in the Stanford test of adult intelligence. These elements of doubt are, I think, radical enough to prohibit anyone from using the results of these tests for large generalization about the quality of human beings. For when people generalize about the quality of human beings they assume an objective criterion of quality, and for testing intelligence there is no such criterion. These puzzles may test intelligence, and they may not. They may test an aspect of intelligence. Nobody knows.