Age-Related Differences in Reaction Time Task Performance in Young Children

Performance of reaction time (RT) tasks was investigated in young children and adults to test the hypothesis that age-related differences in processing speed supersede a "global" mechanism and are a function of specific differences in task demands and processing requirements. The sample consisted of 54 4-year-olds, 53 5-year-olds, 59 6-year-olds, and 35 adults from Russia. Using the regression approach pioneered by Brinley and the transformation method proposed by Madden and colleagues and Ridderinkhoff and van der Molen, age-related differences in processing speed differed among RT tasks with varying demands. In particular, RTs differed between children and adults on tasks that required response suppression, discrimination of color or spatial orientation, reversal of contingencies of previously learned stimulus-response rules, and greater stimulus-response complexity. Relative costs of these RT task differences were larger than predicted by the global difference hypothesis except for response suppression. Among young children, age-related differences larger than predicted by the global difference hypothesis were evident when tasks required color or spatial orientation discrimination and stimulus-response rule complexity, but not for response suppression or reversal of stimulus-response contingencies. Process-specific, age-related differences in processing speed that support heterochronicity of brain development during childhood were revealed. © 2008 Elsevier Inc. All rights reserved.This research was supported in part by a fellowship grant from the International Brain Research Organization to the first author to pursue additional training internationally and by grants from the National Institute of Mental Health (1R01 MH065668), the National Institute on Drug Abuse (1R01 DA014661), and the National Institute of Child Health and Development (5P01 HD038051) to the second author. The authors thank the child and adult participants in the Russian Federation