Tracking the dynamics of global and competitive inhibition in early and late adulthood: Evidence from the flanker task.

Abstract

Inhibitory control is proposed to involve 2 dissociable processes that feature distinct types of inhibition: a threshold adjustment process involving the global inhibition of motor output and a controlled selection process involving competitive inhibition among coactive responses. Recent research with children and young adults indicates that the functioning of these processes can be targeted by measuring participants’ hand movements as they perform inhibitory control tasks by reaching to touch response options on a digital display. The current study explores (a) whether this method can be used to target the functioning of the threshold adjustment process and controlled selection process in adults 65 to 75 years of age and, if so, (b) whether the functioning of each process changes between early and late adulthood. Results from the Eriksen flanker task indicate that reach tracking can be used to target the functioning of each process in late adulthood, with older adults and young adults generating similar patterns of initiation time and curvature effects. The congruency effect observed in response times was significantly larger in older adults than in young adults, indicating that inhibitory control declines in late adulthood. Importantly, this effect was specific to initiation times, suggesting that the threshold adjustment process functions differently in early adulthood than in late adulthood. These results present a new perspective on how age-related differences in inhibitory control are conceptualized and assessed, and raise important questions concerning how the threshold adjustment and controlled selection processes function across a wider range of tasks in late adulthood.