— Cognitive concept

The Flynn Effect

The well-documented rise in raw IQ test performance across the 20th century.

The Flynn effect is the observation, named after researcher James Flynn, that raw IQ test scores rose substantially across the 20th century — by roughly 3 points per decade in most developed countries from 1930 to about 2000.

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What the data shows

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Flynn documented the effect across more than 30 countries. Gains were largest on the most abstract subtests (Raven's Progressive Matrices showed the steepest rise) and smaller on vocabulary and general-knowledge tests. The pattern is roughly consistent: ~3 IQ points per decade on full-scale tests, with bigger gains on pure fluid-reasoning measures.

Why IQ scores still look anchored at 100

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Because tests are re-normed every decade or so. The "average IQ" stays at 100 not because raw cognitive ability is constant, but because each new test edition rescales scores so the new population mean lands at 100. The Flynn effect appears when you measure people on an OLD test edition.

What's caused it

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The honest answer is nobody is sure. Leading hypotheses include:

Better nutrition (especially in early childhood)
Reduced infectious disease burden
Increased schooling years and exposure to abstract reasoning
Greater familiarity with test-taking and abstract symbol manipulation
Smaller family sizes (more parental attention per child)

Is it reversing?

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Several large studies since 2000 (Norway, Denmark, UK, France) have found the Flynn effect has stalled or reversed — small but consistent declines on standardised reasoning tests in recent cohorts. The cause is actively debated; smartphone usage, declining nutrition quality, and educational changes have all been proposed.

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