Mental testing, which led to the concept of the IQ, was a French idea, brainchild of the Nice-born psychologist Alfred Binet. At the beginning of the century Freudian psychology was by no means the only science of behaviour. The Italo-French school of craniometry and stigmata was also popular. This reflected the belief, championed by the Italian Cesare Lombroso and the Frenchman Paul Broca, that intelligence was linked to brain size and that personality – in particular personality defects, notably criminality – was related to facial or other bodily features, what Lombroso called ‘stigmata.’
Binet, a professor at the Sorbonne, failed to confirm Broca’s results. In 1904 he was asked by France’s Minister of Public Education to carry out a study to develop a technique that would help identify those children in France’s schools who were falling behind the others and who therefore needed some form of special education. Disillusioned with craniometry, Binet drew up a series of very short tasks associated with everyday life, such as counting coins or judging which of two faces was ‘prettier.’ He did not test for the obvious skills taught at school – math and reading for example – because the teachers already knew which children failed on those skills.23 Throughout his studies, Binet was very practical, and he did not invest his tests with any mystical powers.24 In fact, he went so far as to say that it didn’t matter what the tests were, so long as there were a lot of them and they were as different from one another as could be. What he wanted to be able to do was arrive at a single score that gave a true reflection of a pupil’s ability, irrespective of how good his or her school was and what kind of help he or she received at home.
Three versions of Binet’s scale were published between 1905 and 1911, but it was the 1908 version that led to the concept of the so-called IQ.25 His idea was to attach an age level to each task: by definition, at that age a normal child should be able to fulfil the task without error. Overall, therefore, the test produced a rounded ‘mental age’ of the child, which could be compared with his or her actual age. To begin with, Binet simply subtracted the ‘mental age’ from the chronological age to get a score. But this was a crude measure, in that a child who was two years behind, say, at age six, was more retarded than a child who was two years behind at eleven. Accordingly, in 1912 the German psychologist W. Stern suggested that mental age should be divided by chronological age, a calculation that produced the intelligence quotient.26 It was never Binet’s intention to use the IQ for normal children or adults; on the contrary, he was worried by any attempt to do so. However, by World War I, his idea had been taken to America and had completely changed character.
The first populariser of Binet’s scales in America was H. H. Goddard, the contentious director of research at the Vineland Training School for Feebleminded Girls and Boys in New Jersey.27 Goddard was a much fiercer Darwinian than Binet, and after his innovations mental testing would never be the same again.28 In those days, there were two technical terms employed in psychology that are not always used in the same way now. An ‘idiot’ was someone who could not master full speech, so had difficulty following instructions, and was judged to have a mental age of not more than three. An ‘imbecile,’ meanwhile, was someone who could not master written language and was considered to have a mental age somewhere between three and seven. Goddard’s first innovation was to coin a new term – ‘moron,’ from the Greek, meaning foolish – to denote the feebleminded individuals who were just below normal intelligence.29 Between 1912 and the outbreak of war Goddard carried out a number of experiments in which he concluded, alarmingly – or absurdly – that between 50 and 80 percent of ordinary Americans had mental ages of eleven or less and were therefore morons. Goddard was alarmed because, for him, the moron was the chief threat to society. This was because idiots and imbeciles were obvious, could be locked up without too much public concern, and were in any case extremely unlikely to reproduce. On the other hand, for Goddard, morons could never be leaders or even really think for themselves; they were workers, drones who had to be told what to do. There were a lot of them, and most would reproduce to manufacture more of their own kind. Goddard’s real worry was immigration, and in one extraordinary set of studies where he was allowed to test the immigrants then arriving at Ellis Island, he managed to show to his own satisfaction (and again, alarm) that as many as four-fifths of Hungarians, Italians, and Russians were ‘moronic.’30
Goddard’s approach was taken up by Lewis Terman, who amalgamated it with that of Charles Spearman, an English army officer who had studied under the famous German psychologist Wilhelm Wundt at Leipzig and fought in the Boer War. Until Spearman, most of the practitioners of the young science of psychology were interested in people at the extremes of the intelligence scale – the very dull or the very bright. But Spearman was interested in the tendency of those people who were good at one mental task to be good at others. In time this led him to the concept of intelligence as made up of a ‘general’ ability, or g, which he believed underlay many activities. On top of g, said Spearman, there were a number of specific abilities, such as mathematical, musical, and spatial ability. This became known as the two-factor theory of intelligence.31
By the outbreak of World War I, Terman had moved to California. There, attached to Stanford University, he refined the tests devised by Binet and his other predecessors, making the ‘Stanford-Binet’ tests less a diagnosis of people in need of special education and more an examination of ‘higher,’ more complex cognitive functioning, ranging over a wider spread of abilities. Tasks included such things as size of vocabulary, orientation in space and time, ability to detect absurdities, knowledge of familiar things, and eye–hand coordination.32 Under Terman, therefore, the IQ became a general concept that could be applied to anyone and everyone. Terman also had the idea to multiply Stern’s calculation of the IQ (mental age divided by chronological age) by 100, to rule out the decimal point. By definition, therefore, an average IQ became 100, and it was this round figure that, as much as anything, caused ‘IQ’ to catch on in the public’s imagination.
It was at this point that world events – and the psychologist Robert Yerkes – intervened.33 Yerkes was nearly forty when the war started, and by some accounts a frustrated man.34 He had been on the staff of the Harvard faculty since the beginning of the century, but it rankled with him that his discipline still wasn’t accepted as a science. Often, for example, in universities psychology was part of the philosophy department. And so, with Europe already at war, and with America preparing to enter, Yerkes had his one big idea – that psychologists should use mental testing to help assess recruits.35 It was not forgotten that the British had been shocked during the Boer War to find out how poorly their recruits rated on tests of physical health; the eugenicists had been complaining for years that the quality of American immigrants was declining; here was a chance to kill two birds with one stone – assess a huge number of people to gain some idea of what the average mental age really was and see how immigrants compared, so that they too might be best used in the coming war effort. Yerkes saw immediately that, in theory at least, the U.S. armed services could benefit enormously from psychological testing: it could not only weed out the weaker men but also identify those who would make the best commanders, operators of complex equipment, signals officers, and so forth. This ambitious goal required an extraordinary broadening of available intelligence testing technology in two ways – there would have to be group testing, and the tests would have to identify high flyers as well as the inadequate rump. Although the navy turned down Yerkes’s initiative, the army adopted it – and never regretted it. He was made a colonel, and he would later proclaim that mental testing ‘had helped to win the war.’ This was, as we shall see, an exaggeration.36