Not your parents' test scores: cohort reduces psychometric aging effects

Abstract

Increases over birth cohorts in psychometric abilities may impact effects of aging. Data from 2 cohorts of the Long Beach Longitudinal Study, matched on age but tested 16 years apart, were modeled over ages 55-87 to test the hypothesis that the more fluid abilities of reasoning, list and text recall, and space would show larger cohort differences than vocabulary. This hypothesis was confirmed. At age 74, average performance estimates for people from the more recently born cohort were equivalent to those of people from the older cohort when they were up to 15 years younger. This finding suggests that older adults may perform like much younger ones from the previous generation on fluid measures, indicating higher levels of abilities than expected. This result could have major implications for the expected productivity of an aging workforce as well as for the quality of life of future generations. However, cohort improvements did not mitigate age declines.

Figure 1

Data plots for individuals on reasoning (top) and vocabulary (bottom) by cohort. Plots include all data from Cohorts 1 and 2 for ages 55 to 87.

Figure 2

Estimated longitudinal changes for vocabulary, space, list recall, text recall, and reasoning for Cohort 1 (C1) and Cohort 2 (C2) between ages 55 and 87 for the two-piece models. The line at age 74 represents the intercept of the models.