Conjoint differences in inhibitory control and processing speed in childhood to older adult cohorts: Discriminant functions from a Go/No-Go task.

To investigate differences in inhibitory control and processing speed over the life span, participants in 7- to 8-, 10- to 11-, 12- to 15-, 18- to 25-, and 54- to 80-year-old age cohorts completed a Go/No-Go task requiring varying levels of semantic categorization. Discriminant function analysis of correct rejection rates (CRRs), hit rates (HRs), and reaction times (RTs) revealed a function on which CRR loaded positively and RT loaded negatively, across categorization levels. Scores increased from youngest to the younger adult cohort and decreased for the older adult cohort. On a second function, CRR and RT loaded positively and HR loaded negatively across categorization levels. Scores were highest for the older adult cohort and higher for the youngest cohort than for the younger adult cohort. The results suggest change along 2 dimensions might underlie cognitive development: (a) combined increased inhibitory control and processing speed and (b) combined increased speed and decreased biased responding for better inhibitory control. In addition, 2 dimensions might underlie senescence: (a) combined decreased inhibitory control and processing speed and (b) combined decreased speed and increased biased responding for better inhibitory control. (PsycINFO Database Record (c) 2018 APA, all rights reserved).