Cognitive Control Across the Lifespan: Congruency Effects Reveal Divergent Developmental Trajectories

The Simon, Stroop, and Eriksen flanker tasks are commonly used to assess cognitive control across the lifespan. However, it remains unclear whether these three tasks in fact measure the same cognitive abilities and in the same proportion. We take a developmental approach to this question: if the Simon, Stroop, and flanker tasks all roughly measure the same capacity, they should show similar patterns of age-related change. We present data from two massive online cross-sectional studies: Study 1 included 9,585 native English speakers between 10 and 80 years of age who completed the Simon and Stroop tasks, and Study 2 included 13,448 English speakers between 10 and 79 years of age who completed the flanker task. Of the three tasks, only the flanker task revealed an inverted U-shaped developmental trajectory, with performance improving until approximately 23 years of age and declining starting around 40 years of age. Performance on the Simon and Stroop tasks peaked around 34 and 26 years of age, respectively, and did not decline significantly in later life, though it is possible that age-related declines would be observed with more difficult versions of the tasks. Although the Simon and Stroop tasks are commonly interpreted to target similar underlying processes, we observed near zero correlations between the congruency effects observed in each task in terms of both accuracy and response time. We discuss these results in light of recent debates regarding the suitability of these tasks for assessing developmental and individual differences in cognitive control. Public Significance Statement Cognitive control-the ability to direct one's thoughts and actions-is a key part of human intelligence. We investigated human cognitive control across the lifespan using three well-known measures of cognitive control. Surprisingly, these three measures provided very different results, challenging current understanding of cognitive control and intelligence over the lifespan.