Generational intelligence test score gains have been documented worldwide in the twentieth century. However, recent evidence suggests these increased scores are coming to an end in some world regions. Here we compare two cohorts of university freshmen. The first cohort (n = 311) was assessed in 1991, whereas the second cohort (n = 349) was assessed thirty years later (2022). These cohorts completed the same intelligence battery including eight standardized speeded and power tests tapping reasoning (abstract and quantitative), language (vocabulary, verbal comprehension, and verbal meanings), rote calculation, and visuospatial relations. The results revealed a global gain of 3.5 IQ points but also upward and downward changes at the test level. The 2022 cohort outperformed the 1991 cohort on reasoning (abstract and quantitative), verbal comprehension, and vocabulary, whereas the 1991 cohort outscored the 2022 cohort on rote calculation, visuospatial relations (mental rotation and identical figures), and verbal meanings. These findings are thought to support one key claim made by James Flynn: generational changes on the specific cognitive abilities and skills tapped by standardized tests should be expected without appreciable or substantive changes in the structure of the intelligence construct identified within generations. This main conclusion is discussed with respect to theoretical causal implications putatively derived from current intelligence psychometric models.
Kevin S. McGrew, PhD
Educational & School Psychologist
Institute for Applied Psychometrics (IAP)