AGE-DIFFERENCES AND CHANGES IN REACTION-TIME - THE BALTIMORE LONGITUDINAL-STUDY OF AGING

This study analyzed auditory reaction time (RT) data from 1,265 commun ity-dwelling volunteers (833 males and 432 females) who ranged in age from 17 to 96. Cross-sectional analyses revealed slowing of simple (SR T) and relatively greater slowing of disjunctive (DRT; aka ''go-no-go' ') reaction time across decades for both males and females. Repeated t esting within participants (longitudinal analyses) over eight gears sh owed consistent slowing and increased variability with age. Males were faster than females across age groups, RT tasks, and visits. Beginnin g at about age 20, RTs increased at a rate of approximately 0.5 msec/y r for SRT and 1.6 msec/yr for DRT. Errors also increased, making unlik ely a tradeoff of accuracy for faster responses. The findings are cons istent with the hypotheses that slowing of behavior is: (a) a continuo us process over the adult life span; (6) characterized by age-associat ed increases in within-participant variability; (c) a direct function of task complexity and, presumably, the degree of mediation by higher regions in the central nervous system; and (d) greater in women than m en.