Cognition in Flux: Evidence of a Reverse Flynn Effect in U.S. Adults

A Northwestern study analyzing 394,378 U.S. adults (2006–2018) finds a reverse Flynn effect: composite cognitive scores declined over time across most age groups and education levels, especially among 18–22-year-olds and those with less education, with declines in matrix reasoning and verbal/sequence tasks but improvement in three-dimensional rotation. Verbal ability changed little and major tests like ACT/SAT also fell. The causes are unknown and the cross‑sectional data cannot establish causation; trends predate AI and COVID. Published in Intelligence.