Flynn effect: a standalone construct

James R. Flynn documented the pattern in two studies, first showing in The mean IQ of Americans: Massive gains 1932 to 1978 (1984) that Americans scored steadily higher on intelligence tests across successive birth cohorts, so that test norms had to be revised upward over time, and then in Massive IQ gains in 14 nations (1987) that the same upward trend held across many countries. The finding is that raw performance on standardized IQ tests rose from one generation to the next, on the order of a few points per decade, meaning a person scoring at the average of an earlier decade would score below average against a later cohort measured on the same test. Richard Herrnstein and Charles Murray gave the pattern its common name, the Flynn effect, in their 1994 book The Bell Curve. What makes the finding a landmark is its scope: it is a robust, repeatedly replicated population-level trend rather than a claim about any one person, and because IQ scores are periodically re-normed to a fixed mean, the rise is visible only when older norms are compared against newer ones.[1][2][3]

Unit

Change in mean standardized IQ score per birth cohort or per decade, on a scale normed to a mean of 100

Recovery means

Not applicable

Measured by

Identified by comparing the same or equivalent IQ tests administered to different birth cohorts, typically through re-standardization samples where an older and a newer test are given to the same people