"Let us then give reins to our fancy, and imagine a Utopia...in which a system of competitive examinations...had been so developed as to embrace every important quality of mind and body, and where a considerable sum was alloted to the endowment of such marriages as promised to yield children who would grow into eminent servants of the State. We may picture to ourselves an annual ceremony in that Utopia, in which the Senior Trustee of the Endowment Fund would address ten deeply-blushing young men, all of twenty-five years old, in the following terms:-"Gentlemen, I have to announce the results of a public examination, conducted on established principles; which show that you occupy the foremost places in your year, in respect to those qualities of talent, character, and bodily vigour which are proved, on the whole, to do most honour and best service to our race. An examination has also been conducted on established principles among all the young ladies of this country who are now of the age of twenty-one, and I hardly need remind you, that this examination takes note of grace, beauty, health, good-temper, accomplished hiusewifery, and disengaged affections, in addition to the noble qualities of heart and brain. By a careful investigation of the marks you have severally obtained... we have been enabled to select ten of [the young ladies] names with special reference to your individual qualities. It appears that marriages between you and these ten ladies, according to the list I hold in my hand, would offer the probability of unusual happiness to yourselves, and what is of paramount interest to the State, would probably result in an extraordinarily talented issue."
In 1884 Galton used his "Anthropometric Laboratory" at the International Health Exhibition in London to take measurements on a very large number of people. His intention was to develop a test of intelligence. He started with physical measures, such as head size. Galton had noticed that particularly intelligent people had large heads, and consistent with his Victorian misogynist bias he found the smaller average head size of women to be strong support for his idea that intelligence was reflected by size of the head. However, Galton realized that head size alone was an imperfect indicator of ability. Fancher says that he was helped in this realization by the extremely small size of his own head.The other measure that occured to Galton was general speed or efficiency of the nervous system, as measured by reaction time: how quickly a person could respond to a stimulus. His other tests measured sensory acuity: the fineness of visual and auditory discriminations. Galton's nine thousand subjects paid three pence each to take his tests. His plan to used such tests for individualized eugenics assessments remained utopian hope in the 1880s.
These "mental tests" were taken up with enthusiasm by a Cornell professor, Cattell who expanded them into a larger test, adding items such as time for naming colors, and judgement of ten seconds of time. During the 1890s these tests were administered in a number of countries. Gradually, however, it bacame clear that they were not measuring what they purported to test for: intellectual ability. One of Cattell's own students, Wissler, used newly developed statistical techniques to determine that there was virtually no correlation between class standing at Columbia and Barnard and mental test scores. Correlation coefficients vary from +1 for a perfect positive correlation to -1 for a perfect negative correlation. Class standing correlated -.02 with reaction time and +.02 with color naming. Further, scores on individual tests did not correlate well with each other.
Binet was a strong advocate of the importance of individual differneces. He was convinced that intelligence could appear in highly diverse manifestations. This conviction sprang from his observation of the profound differences in character and intellectual style between his two girls. He called one 'l'observateur' (the observer) and the other 'l'imaginitif' (the imaginer). For example, here are the teenaged girls reponses to being asked to describe a chestnut leaf:
l'observateur: "The leaf I am looking at is a chestnut leaf gathered in the autumn, because the folioles are all almost yellow except for two, and one is half green and yellow. This leaf is composed of several folioles joined at a center which ends on the stem called a petiole, which supports the leaf on the tree. The folioles are not of the same size; out of the 7, 4 are much smaller than the 3 others. The chestnut tree is a docotyledon, as one can tell by looking at the leaf, which has ramified nervures."Compare this with his other daughter's response:
l'imaginitif: "This is a chestnut tree leaf which has just fallen languidly in the autumn wind...Poor leaf, destined now to fly along the streets, then to rot, heaped up with the others. It is dead today, and it was alive yesterday! Yesterday, hanging from the branch it awaited the fatal flow of wind that would carry it off, like a dying person who awaits the final agony. But the leaf did not sense its danger, and it fell softly in the sun."Binet understood well that two equally intelligent people could go about solving the same problem in completely different ways. This appreciation of individual differences underpinned Binet's disinclination to rely on "brute numbers" in summing up a person's capacities.
In 1904 Binet was appointed to a governmental commission charged with investigating the state of the mentally subnormal in France. Recently enacted universal education laws required that all French children be given public education. Binet and Simon's 1905 test was devised to distinguish between mentally subnormal children and normal children. The basic insight that drove the design of the test items is that of measuring with respect to age. They found that the subnormal children's performance could be equated with that of much younger normal children. In the 1905 Binet-Simon test and its subsequent 1908 and 1991 revisions they devised age linked items that should be witih the capacities of a child of that age. For example, at age three typical normal children could point at request to body parts, name common objects from a printed picture, repeat back correctly two spoken numbers, and give their last names; at age ten normal children could reproduce line drawings from memory, compose a sentence containing the three words "Paris", "fortune" and "stream", and detect and explain absurdities in stories such as: "Someone said that if I should ever get desperate and kill myself, I should not choose Friday, because Friday is an unlucky day and will bring unhappiness". The important thing to note is that these items area hodge-podge of different things, brought together only by the general ability of children of a certain age to answer them correctly.
Binet observed that children varied a great deal in the particular items that they could answer, and that there was substantial variability from test to test for the same child. He developed the rule of thumb that a score of two years below chronological age would result in the child experiencing difficulty in ordinary schools. It is important to note that Binet believed that intelligence itself was liable to substantial change within an individual; he did not take a hereditarian view of intelligence. He believed that there was always room for improvement; there may be an upper limit for each person's intelligence, but few people actually approach that limit in real life. Binat developed a program of "mental orthopedics" which included the game of "Statue" and a Memory game to develop attention and memory. In this Binet differed radically from Galton: Binet regarded intelligence as fluid and subject to change through learning, whereas Galton saw it as a fixed hereditary characteristic. It is no coincidence that these two men were concerned with opposite ends of the spectrum: Binet felt his tests were only appropriate at the lower end of the distribution, in diagnosing difficulties in learning, whereas Galton focused on the top end of the scale, emphasizing genius which he took to be hereditary.