IQ test scores rose across many populations during much of the twentieth century, at rates varying by country, test and ability domain.
Flynn found gains of roughly three points per decade, largest on abstract-reasoning subtests and smallest on vocabulary and arithmetic. Gains have since slowed, stalled or reversed in some populations.
In practice
- An aptitude test normed in 1985 rates a 2010 cohort as above average across the board, and the test is renormed rather than the cohort celebrated.
- A school comparing this year's raw scores with a decade ago must adjust for the drift before the comparison means anything.
- Possible explanations
- Candidate explanations include better nutrition and health, more and longer schooling, smaller families, greater familiarity with tests, and work that demands more abstract classification than it did a century ago.
- In its favour
- The rise is documented across many countries, tests and decades, and was large enough that test norms had to be reset repeatedly.
- Against it
- What rose is disputed: measurement studies find the gains are not equivalent across tests, so they may not represent gains in general ability, and the trend has stalled or reversed in several countries since the 1990s.
- Standing
- Has stalled or reversed in several countries since the 1990s.
- Further reading
- Wikipedia
- Subject
- Sociology & Culture
- Essay
- The measured patterns of social life