Library Collections: Document: Full Text

This is the first of a series of six articles, an analysis and estimate of intelligence tests. It is a critical enquiry into the claim, now widely made and accepted, that the psychologists have invented a method of measuring the inborn intelligence of all people. The series will discuss what sort of measure the tests furnish, beginning with a description of how the tests are made up. It goes on to discuss the claim that psychologists test intelligence which is fixed by heredity, and is therefore more or less impervious to education and environment. It concludes with some comment on the future usefulness of the tests. -- THE EDITORS.

A STARTLING bit of news has recently been unearthed and is now being retailed by the credulous to the gullible. "The average mental age of Americans," says Mr. Lothrop Stoddard in The Revolt Against Civilization, "is only about fourteen."

Mr. Stoddard did not invent this astonishing conclusion. He found it ready-made in the writings of a number of other writers. They in their turn got the conclusion by misreading the data collected in the army intelligence tests. For the data themselves lead to no such conclusion. It is impossible that they should. It is quite impossible for honest statistics to show that the average adult intelligence of a representative sample of the nation is that of an immature child in that same nation. The average adult intelligence cannot be less than the average adult intelligence, and to anyone who knows what the words "mental age" mean, Mr. Stoddard's remark is precisely as silly as if he had written that the average mile was three quarters of a mile long.

The trouble is that Mr. Stoddard uses the words "mental age" without explaining either to himself or to his readers how the conception of "mental age" is derived. He was in such an enormous hurry to predict the downfall of civilization that he could not pause long enough to straighten out a few simple ideas. The result is that he snatches at a few scarifying statistics and uses them as a base upon which to erect a glittering tower of generalities. For the statement that the average mental age of Americans is only about fourteen is not inaccurate. It is not incorrect. It is nonsense.

Mental age is a yard stick invented by a school of psychologists to measure "intelligence." It is not easy, however, to make a measure of intelligence and the psychologists have never agreed on a definition. This quandary presented itself to Alfred Binet. For years he had tried to reach a definition of intelligence and always he had failed. Finally he gave up the attempt, and started on another tack. He then turned his attention to the practical problem of distinguishing the "backward" child from the "normal" child in the Paris schools. To do this he had to know what was a normal child. Difficult as this promised to be, it was a good deal easier than the attempt to define intelligence. For Binet concluded, quite logically, that the standard of a normal child of any particular age was something or other which an arbitrary percentage of children of that age could do. Binet therefore decided to consider "normal" those abilities which were common to between 65 and 75 percent of the children of a particular age. In deciding on these percentages he thus decided to consider at least twenty-five percent of the children as backward. He might just as easily have fixed a percentage which would have classified ten percent of the children as backward, or fifty percent.

Having fixed a percentage which he would henceforth regard as "normal" he devoted himself to collecting questions, stunts and puzzles of various sorts, hard ones and easy ones. At the end he settled upon fifty-four tests, each of which he guessed and hoped would test some element of intelligence; all of which together would test intelligence as a whole. Binet then gave these tests in Paris to two hundred school children who ranged from three to fifteen years of age. Whenever he I found a test that about sixty-five percent of the children of the same age could pass he called that a Binet test of intelligence for that age. Thus a mental age of seven years was the ability to do all the tests which sixty-five to seventy-five percent of a small group of seven year old Paris school children had shown themselves able to do.

This was a promising method, but of course the actual tests rested on a very weak foundation indeed. Binet himself died before he could carry his idea much further, and the task of revision and improvement was then transferred to Stanford University. The Binet scale worked badly in California. The same puzzles did not give the same results in California as in Paris. So about 1910 Professor L. M. Terman undertook to revise them. He followed Binet's method. Like Binet he would guess at a stunt which might indicate intelligence, and then try it out on about 2,300 people of various ages, including 1,700 children "in a community of average social status." By editing, rearranging and supplementing the original Binet tests he finally worked out a series of tests for each age which the average child of that age in about one hundred Californian children could pass.

Page 2:

The puzzles which this average child among a hundred Californian children of the same age about the year 1913 could answer are the yardstick by which "mental age" is measured in what is known as the Stanford Revision of the Binet-Simon Scale. Each correct answer gives a credit of two months' mental age. So if a child of seven can answer all tests up to the seven-year-old tests perfectly, and cannot answer any of the eight-year-old tests, his total score is seven years. He is said to test "at age," and his "intelligence quotient" or "I. Q." is unity or 100 percent. Anybody's I. Q. can be figured, therefore, by dividing his mental age by his actual age. A child of five who tests at four years' mental age has an I. Q. of 80 (4/5 = .80). A child of five who tests at six years' mental age has an I. Q, of 120 (6/5 = 120).

The aspect of all this which matters is that "mental age" is simply the average performance with certain rather arbitrary problems. The thing to keep in mind is that all the talk about "a mental age of fourteen" goes back to the performance of eighty-two California school children in 1913-14. Their success and failures on the days they happened to be tested have become embalmed and consecrated as the measure of human intelligence. By means of that measure writers like Mr. Stoddard fix the relative values of all the peoples of the earth and of all social classes within the nations. They don't know they are doing this, however, because Mr. Stoddard at least is quite plainly taking everything at second hand.

However, I am willing for just a moment: to grant that Mr. Terman in California has worked out a test for the different ages of a growing child. But I insist that anyone who uses the words "mental age" should remember that Mr. Terman reached his test by seeing what the average child of an age group could do. If his group is too small or is untypical his test is in the same measure inaccurate.

Remembering this, we come to the army tests. Here we are dealing at once with men all of whom are over the age of the mental scale. For the Stanford-Binet scale ends at "sixteen years." It assumes that intelligence stops developing at sixteen and everybody sixteen and over is therefore treated as "adult" or as "superior adult." Now the adult Stanford-Binet tests were "standardized chiefly on the basis of results from 400 adults" (Terman p. 13) "of moderate success and of very limited educational advantages" and also thirty-two high school pupils from sixteen to twenty years of age. Among these adults those who tested close together have the honor of being considered the standard of average adult intelligence.

Before the army tests came along, when anyone talked about the average adult he was talking about a few hundred Californians. The army tested about 1,700,000 adult men. But it did not use the Binet system of scoring by mental ages. It scored by a system of points which we need not stop to describe. Naturally enough everyone interested in mental testing wanted to know whether the army tests agreed in any way with the Stanford-Binet mental age standard. So by another process, which need also not be described, the results of the army tests were translated into Binet terms. The result of this translation is the table which has so badly misled poor Mr. Stoddard. This table showed that the average of the army did not agree at all with the average of Mr. Terman's Californians. There were then two things to do. One was to say that the average intelligence of 1,700,000 men was a more representative average than that of four hundred men. The other was to pin your faith to the four hundred men and insist they gave the true average.

Mr. Stoddard chose the average of four hundred rather than the average of 1,700,000 because he was in such haste to write his own book that he never reached page 785 of Psychological Examining in the United States Army, the volume of the data edited by Major Yerkes. (1) He would have found there a clear warning against the blunder he was about to commit, the blunder of treating the average of a small number of instances as more valid than the average of a large number.

Page 3:

But instead of pausing to realize that the army tests had knocked the Stanford-Binet measure of adult intelligence into a cocked hat, he wrote his book in the belief that the Stanford measure is as good as it ever was. This is not intelligent. It leads one to suspect that Mr. Stoddard is a propagandist with a tendency to put truth not in the first place but in the second. It leads one to suspect, after such a beginning, that the real promise and value of the investigation which Binet started is in danger of gross perversion by muddleheaded and prejudiced men.

WALTER LIPPMANN.

(To be continued next week)