The Stanford–Binet Intelligence Test

What is the Stanford-Binet IQ test? The world’s most famous intelligence test—created in 1905 by Binet, revised by Terman in 1916, still used today for gifted placement & clinical diagnosis. Discover its history and how to take the real one.

Dr. Russell T. WarneChief Scientist

The Stanford–Binet Intelligence Test is one of the most famous tests in psychology. It originated from the work of Alfred Binet and Théodore Simon, who in 1905 created the first successful intelligence test to identify children needing additional academic support. Their concept of mental age, comparing a child’s performance to the average for each age group, established the foundation for modern intelligence testing.

In 1916, Stanford University psychologist Lewis Terman translated and revised Binet’s test for use in the United States. His version, the Stanford–Binet Intelligence Scale, expanded the range of questions, adapted content for American examinees, and introduced standardized scoring. This revision transformed intelligence testing from an educational experiment into a formal psychological tool, setting the standard for future assessments.

Evolution of the Test

Over the past century, the Stanford–Binet has undergone several revisions to reflect advances in theory and statistical methods. Early editions used the ratio IQ formula, in which mental age was divided by chronological age and multiplied by 100. The IQs this method produced were easy to understand, but it had problems for comparing scores across age groups. It was later replaced by the modern deviation IQ, which compares scores to the average performance of same-age peers.

The modern Stanford-Binet test produces an overall IQ and also scores for its Fluid, Knowledge, Quantitative, Visual-Spatial, and Working Memory Indexes. The test produces other scores that may be useful for specific examinees or specific contexts.

Significance and Use

The Stanford–Binet is used worldwide in educational, clinical, and research settings. In schools, it helps identify students who may qualify for gifted programs or require additional academic support. Clinicians use it to assess developmental delays, intellectual disabilities, and other cognitive conditions. Because intelligence is influenced by many factors, psychologists interpret results alongside other data such as academic history, behavioral observations, and health information.

The Stanford-Binet’s continued use reflects its strong reliability and validity. The modern edition is standardized on a large, representative sample that includes diverse demographic groups. The test has been subjected to outside professional scrutiny and has found acceptance among psychologists and other clinicians.

Influence on Modern Testing

The Stanford–Binet shaped nearly every intelligence test developed since. Data collected from successive editions have also provided valuable insights into cognitive development across the lifespan and the stability of intelligence over time.

Watch “What Does an IQ Test Measure?” with Dr. Russell T. Warne on the Riot IQ YouTube channel to understand what the Stanford-Binet test is really designed to assess.