Alfred Binet

Introduction

Alfred Binet (1857–1911) was the French psychologist who built the first practical intelligence test — and who spent the last years of his life warning that it must not be used the way it subsequently was.

The 1905 Binet–Simon scale was commissioned for a specific and humane purpose: to identify Parisian children who were struggling in ordinary classrooms so that they could be given help rather than expelled into asylums. Binet and Théodore Simon succeeded, and the instrument they built is the ancestor of essentially every intelligence test since.

What happened next is the part that is usually omitted. Binet insisted that his scale measured a child's current standing, not a fixed endowment; that a low score called for remedial teaching, not a verdict; and that intelligence was too various to be captured in a single number. Within five years of his death, his test had been translated, standardised, and turned into an instrument for ranking people by innate worth — used to justify immigration restrictions and compulsory sterilisation in the United States. He had argued against exactly this, in print, in advance.

Early Life and Education

Binet was born on 8 July 1857 in Nice. His father was a physician and his mother a painter; the couple separated, and he moved to Paris with his mother while still a boy. He trained in law in Paris and qualified, but never practised; instead he drifted into psychology by way of the Salpêtrière hospital and the library of the Bibliothèque Nationale, reading himself into the subject more or less unsupervised. He had no formal doctorate in psychology, which in the French university system of the time was a serious professional handicap that followed him throughout his career — he never held a professorship, and the Sorbonne post he eventually directed was a laboratory directorship rather than a chair.

The Salpêtrière connection, where he worked with Jean-Martin Charcot, produced his first body of research, on hypnosis and suggestibility. It also produced the most instructive episode of his early career. Binet and his colleagues published results on hypnotic phenomena — transfer of symptoms, the effects of magnets — that were consistent with Charcot's claims. Then Binet noticed that his subjects were responding to what they believed the experimenter expected, and that the phenomena disappeared when the cues were removed.

He published a retraction. It cost him his position with Charcot and his standing in that circle, but it established the pattern of the rest of his career: a willingness to abandon a result, including his own, when the method could not support it. It also gave him a permanent methodological preoccupation with suggestion effects — which is why his later work on intelligence testing is unusually careful about examiner influence, and why the testing instructions he wrote spend so long on what the examiner must not do.

In 1891 he began work at the Sorbonne's laboratory of experimental psychology, becoming its director in 1894 — a post he held for the remaining seventeen years of his life. With Victor Henri he founded L'Année Psychologique in 1895, the first French journal of psychology, which remains a significant publication.

Academic and Professional Career

Binet's research before 1900 was wide-ranging and mostly on individual differences in high-level abilities. He studied the memory of chess masters, investigating what is now called expertise — he found that skilled blindfold players retained not the literal positions of pieces but abstracted structural features, and that the ability did not transfer to other material, which was itself the interesting result. He studied arithmetical prodigies, and concluded that their performance depended on specific trained procedures rather than general mental speed. He worked on graphology and declared it worthless — a rare and useful negative result in a field where practitioners simply decline to be tested.

In 1903 he published L'Étude Expérimentale de l'Intelligence, an intensive observational study of his own two daughters, Marguerite and Alice. He described them as contrasting types — one imaginative and inward, the other observant and outward — and used the contrast to argue that individual differences in cognition are qualitative as well as quantitative. The study is now regarded as a forerunner of work on cognitive styles, and it is the clearest statement of what Binet thought intelligence actually was: not a quantity a person has more or less of, but a way of approaching problems that differs from one person to another.

In 1904 the French Ministry of Public Instruction appointed him to a commission on the education of children who could not benefit from ordinary teaching. The commission's purpose was to distinguish children who were genuinely unable to learn from children who were unruly or under-taught — because the prevailing practice was to remove the former to asylums on the judgement of physicians, which Binet, with his history at the Salpêtrière, had good reason to distrust.

He and Théodore Simon, a psychiatrist working with children, built a scale of graduated tasks — following commands, naming objects, defining words, comparing quantities, constructing sentences — ordered by difficulty and calibrated against what ordinary children of each age could do. It was published in 1905, revised in 1908 with the explicit introduction of mental age, and revised again in 1911 shortly after Binet's death.

Major Contributions to Psychology

The Binet–Simon scale

The innovation was not the individual tasks — most were borrowed from earlier sensory and motor testing — but the organisation. Items were calibrated empirically against age groups, so a child's performance was expressed as a mental age rather than a pass/fail on a fixed standard. A six-year-old who passed only what typical six-year-olds passed had a mental age of six; one who passed what typical eight-year-olds passed had a mental age of eight.

The point was comparative and diagnostic, not absolute. It told a teacher how far behind a child was and what level of work to pitch at them.

Mental orthopedics

Binet's remedy was not classification but training. He developed exercises he called orthopédie mentale — mental orthopedics — aimed at attention, memory, and judgment, on the explicit premise that these capacities could be improved with practice. This was not incidental to the test; it was the reason for it. Identify the child, then train the child.

Individual differences as the proper object of psychology

Across his career Binet argued that psychology had neglected the study of how people differ, in favour of the study of how people are alike. His chess and calculation research, his work on twins, and his testing programme were all instances of the same conviction: that general laws of mind obscure more than they reveal, and that the interesting structure is in the variation.

Major Publications

La Psychologie du Raisonnement (1886) — on reasoning, drawing on his suggestibility work
Les Altérations de la Personnalité (1892)
Introduction à la Psychologie Expérimentale (1894, with others)
L'Étude Expérimentale de l'Intelligence (1903) — the study of his two daughters, and a founding text of differential psychology
Les Idées Modernes sur les Enfants (1909)
The Binet–Simon scales (1905, 1908, 1911), with Théodore Simon

Impact and Legacy

Every intelligence test in the world descends from Binet's scale, and the mental-age concept was carried forward into the ratio IQ that William Stern proposed in 1912 and that Lewis Terman built into the Stanford–Binet in 1916. The intelligence testing enterprise as a whole — for better and worse — is his descendant.

What he warned against, and what happened anyway. Binet stated his objections clearly and repeatedly:

The scale does not measure innate intelligence. It measures a child's present level, which is a function of schooling, health, and circumstances as much as of anything intrinsic. Comparing children from different backgrounds with it is invalid.
Intelligence is not a single quantity. He conceptualised it as judgment — practical sense, the ability to adapt and to self-criticise — and considered it too complex and too variable to be reduced to a number.
A low score must never become a label. He used the phrase "a brutal pessimism" about children who test poorly, and argued that the appropriate response is teaching, not classification.

Within a decade of his death all three warnings had been discarded. Henry Goddard translated the scale into English in 1910 and used it at Ellis Island to identify "feeble-minded" immigrants, reporting figures that influenced US immigration restriction. Terman's Stanford revision presented the test as measuring innate general intelligence and used it to classify the entire American school population. The Army Alpha and Beta testing programme of the First World War scaled it further. These uses produced the hereditarian interpretation of intelligence testing that Binet had explicitly rejected, and supplied the psychometric apparatus for the American eugenics movement.

Criticism of Binet himself. His contribution has its own limitations. The scale was standardised on a small sample of Parisian schoolchildren, and the age-graded item calibration was crude by later standards — a child's mental age was determined by the hardest items passed, with no measurement error attached and no way of saying how far above or below a level a child really was.

More fundamentally, Binet was not a psychometrician and did not have one available to him. He built his instrument before the statistical machinery that makes a modern test defensible existed: no factor analysis, no item-response theory, no reliability coefficients, no systematic treatment of measurement error. His criterion for including an item was simply that most children of a given age passed it. That made the scale usable and it made it fragile, and it is a large part of why the same instrument could be taken up as a scientific measure of innate capacity by people who wanted one. A tool built without error estimates is easy to over-interpret.

He also never produced a theory of intelligence to go with the test. Charles Spearman supplied g afterwards, and the field has argued about what the test measures ever since — an argument Binet's own writings do not settle, because he did not think there was a single thing to be measured. Later psychometricians have treated that as a weakness in his work; it can equally be read as a deliberate refusal that his successors overruled.

His mental orthopedics was never shown to work; enthusiasm for training general mental faculties has not fared well under controlled evaluation, and the transfer he assumed has repeatedly failed to materialise. The mental-age concept itself is problematic — it implies a smooth quantity that stops changing at adulthood, which is not how cognitive development works, and it produces the absurdity of adult mental ages being treated as equivalent to children's.

And there is the uncomfortable fact that the instrument he built proved far more usable for sorting than for teaching. He designed a diagnostic tool to route children into help; what the world wanted was a ranking device, and the design made an excellent one. Whether that is a failure of his foresight or of his successors' intentions is a question worth sitting with — he did warn them, and it did not help.

Learn More

Charles Spearman — whose g supplied the theory that Binet's test was later taken to measure
Lewis Terman — who made the Stanford revision, and rejected Binet's cautions
Louis Thurstone — whose multiple-abilities theory is closer to what Binet actually believed
Human Intelligence — the construct, and how badly it resists single-number measurement

References

Binet, A., & Simon, T. (1905). New methods for the diagnosis of the intellectual level of subnormals. L'Année Psychologique, 12, 191-244.