Alfred Binet

French psychologist (1857–1911), director of the laboratory of physiological psychology at the Sorbonne and the author, with the physician Théodore Simon, of the first practical scale for measuring intelligence. He was largely self-taught in psychology — he read Ribot and the English associationists in the library of the Bibliothèque nationale after abandoning law — and his early years at the Salpêtrière under Charcot ended in a public humiliation when his experiments on hypnotic transfer were shown to be an artefact of suggestion, a lesson in experimental control that marked everything he did afterwards.

He founded L'Année psychologique in 1894, studied the memory of chess players who played blindfold, the psychology of calculating prodigies, the reliability of children's testimony, and the individual differences between his own two daughters, Madeleine and Alice, whom he observed for years and made the subject of L'Étude expérimentale de l'intelligence (1903). In 1904 the French ministry of public instruction asked him to find a way of identifying children who could not follow ordinary schooling, and the Binet–Simon scale of 1905, revised in 1908 and 1911, answered it with a graded series of everyday tasks — following a light, repeating digits, defining words, spotting an absurdity — arranged by the age at which most children pass them, from which came the notion of mental age.

Binet was explicit about the limits of what he had built: the scale was a practical instrument for finding children who needed help, not a measure of a fixed quantity, and he argued for what he called mental orthopaedics, the training of attention and judgement, against the fatalism of those who took a low score for a verdict. The Stanford revision that turned his scale into the intelligence quotient came after his death, and used it in exactly the way he had warned against.