The mean IQ of Americans: Massive gains 1932 to 1978.

1984/01/01 by James R. Flynn · 17 citations
Psychology · #Cognitive Abilities and Testing

paper · doi:10.1037/0033-2909.95.1.29

openalex publication_date 1984/01/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/08

Abstract

This study shows that every Stanford-Binet and Wechsler standardization sample from 1932 to 1978 established norms of a higher standard than its predecessor. The obvious interpretation of this pattern is that representative samples of Americans did better and better on IQ tests over a period of 46 years, the total gain amounting to a rise in mean IQ of 13.8 points. The implications of this finding are developed: The combination of IQ gains and the decline in Scholastic Aptitude Test scores seems almost inexplicable; obsolete norms have acted as an unrecognized confounding variable in hundreds of studies; and IQ gains of this magnitude pose a serious problem of causal explanation.

Citations

• Mr. Binet’s Test 70 Years Later

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• Intelligence: Knowns and unknowns.
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• Kids These Days! Increasing delay of gratification ability over the past 50 years in children
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• Flynn effect [wikipedia]
• Intelligence quotient [wikipedia]
• James Flynn (academic) [wikipedia]
• Richard Lynn [wikipedia]