Aging, cohorts, and verbal ability

Objectives. Age-related differences in cognitive abilities observed in cross-sectional samples of individuals varying in age may in part be spurious due to the effects of cohort differences in schooling and related factors. This study examined the effects of aging on cognitive function controlling for any and all differences in cohort-based social experiences of different age groups. Methods. We examined age-related patterns in a measure of verbal ability using 14 repeated cross-sectional surveys from the General Social Survey (GSS) over a 24-year period. Results. The raw GSS data show the expected age-related growth and decline in vocabulary knowledge, but these age differences are reduced when adjusted for cohort differences. There is evidence of small age-related patterns in vocabulary knowledge within cohorts, but the curvilinear contributions of aging to variation in verbal scores account for less than one-third of 1% of the variance in vocabulary knowledge, once cohort is controlled. Cohort differences in schooling contribute substantially to this effect. Discussion. Within-age-group variation in vocabulary knowledge is vastly more important than age differences per se, and the complexities of the relationship of verbal skills to historical differences in the experience of schooling present an interesting avenue for future research.