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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.

What then do the tests accomplish? I think we can answer this question best by starting with an illustration. Suppose you wished to judge all the pebbles in a large pile of gravel for the purpose of separating them into three piles, the first to contain the extraordinary pebbles, the second the normal pebbles, the third the insignificant pebbles. You have no scales. You first separate from the pile a much smaller pile and pick out one pebble which you guess is the average. You hold it in your left hand and pick up another pebble in your right hand. The right pebble feels heavier. You pick up another pebble. It feels lighter. You pick up a third. It feels still lighter. A fourth feels heavier than the first. By this method you can arrange all the pebbles from the smaller pile in a series running from the lightest to the heaviest. You thereupon call the middle pebble the standard pebble, and with it as a measure you determine whether any pebble in the larger pile is a subnormal, a normal or a supernormal pebble.

This is just about what the intelligence test does. It does not weigh or measure intelligence by any objective standard. It simply arranges a group of people in a series from best to worst by balancing their capacity to do certain arbitrarily selected puzzles, against the capacity of all the others. The intelligence test, in other words, is fundamentally an instrument for classifying a group of people. It may also be an instrument for measuring their intelligence, but of that we cannot be at all sure unless we believe that M. Binet and Mr. Terman and a few other psychologists have guessed correctly when they invented their tests. They may have guessed correctly but, as we shall see later, the proof is not yet at hand.

The intelligence test, then, is an instrument for classifying a group of people, rather than "a measure of intelligence." People are classified within a group according to their success in solving problems which may or may not be tests of intelligence. They are classified according to the performance of some Californians in the years 1910 to about 1916 with Mr. Terman's notion of the problems that reveal intelligence. They are not classified according to their ability in dealing with the problems of real life that call for intelligence.

With this in mind let us look at the army results, as they are dished up by writers like Mr. Lothrop Stoddard and Professor McDougall of Harvard. The following table is given:

4 % of the army were A men
9 % of the army were B men
16 1/2 % of the army were C+ men
25 % of the army were C men
20 % of the army were C- men
15 % of the army were D men
10 % of the army were D- men

But how, you ask, did the army determine the qualities of an "A" man? For an "A" man is supposed to have "very superior intelligence," and of course mankind has wondered for at least two thousand years what were the earmarks of very superior intelligence. McDougall and Stoddard are quite content to take the army's word for it, or at least they never stop to explain, before they exploit the figures, what the army meant by "very superior inelligence -sic-." The army, of course, had no intention whatever of committing itself to a definition of very superior intelligence. The army was interested in classifying recruits. It therefore asked a committee of psychologists to assemble from all the different systems, Binet and otherwise, a series of tests. The committee took this series and tried it out in a few camps. They timed the tests. "The number of items and the time limits were so fixed that five percent or less in any average group would be able to finish the entire series of items in the time allowed." (1) It is not surprising, therefore, that five percent or less (4 1/2 percent actually) of the army made a top score. It is not surprising that tests devised to pass five percent or less "A" men should have passed four and a half percent "A" men.

The army was quite justified in doing this because it was in a hurry and was looking for about five percent of the recruits to put into officers' training camps. I quarrel only with the Stoddards and McDougalls who solemnly talk about the 4 1/2 percent "A" men in the American nation without understanding how these 4 1/2 percent were picked. They do not seem to realize that if the army had wanted half the number of officers, it could by shortening the time have made the scarcity of "A" men seem even more alarming. If the army had wanted to double the "A" men, it could have done that by lengthening the time. Somewhere, of course, in the whole group would have been found men who could not have answered all the questions correctly in any length of time. But we do not know how many men of the kind there were because the tests were never made that way. (2)

The army was interested in discovering officers and in eliminating the feeble-minded. It had no time to waste, and so it adopted a rough test which would give a quick classification. In that it succeeded on the whole very well. But the army did not measure the intelligence of the American nation, and only very loose-minded writers imagine that it did. When men write as Mr. Stoddard does that "only four and a half millions -of the whole population- can be considered 'talented,'" the only possible comment is that the statement has no foundation whatsoever. We do not know how many talented people there are: first, because we have no measure of talent, and second, because we have never made the attempt to devise one or apply one. But when we see how men like Stoddard and McDougall have exploited the army tests, we realize how necessary, but how unheeded, is the warning of Messrs. Yoakum and Yerkes that "the ease with which the army group test can be given and scored makes it a dangerous method in the hands of the inexpert. It was not prepared for civilian use, and is applicable only within certain limits to other uses than that for which it was prepared."

WALTER LIPPMANN.

(To be continued.)