From the 1930s, IQ scores seemed to be inching up – with each new generation scoring a little higher than the last. This increase was called the "Flynn Effect" after the educator James Flynn, who published about it in 1984. She and her colleagues analyzed cognitive test scores from nearly 400,000 American adults collected between 2006 and 2018. Composite cognitive scores declined over time, with the trend appearing across age groups, education levels, and in both men and women. Verbal reasoning showed comparatively little change, with declines too small to meet the researchers' threshold for a meaningful reverse Flynn effect.