Longitudinal Analysis of Age-Related Slowing: BLSA Reaction Time Data

Abstract

Reported are preliminary findings from analyses of cross-sectional and longitudinal reaction time data collected on 865 male and 453 female volunteers who ranged in age from 20 to 96 years. Evident in both simple and disjunctive reaction time measures was a consistent slowing with age. In nearly all cases, males were faster than females but gender differences were negligible for the simple reaction time (SRT) compared to disjunctive reaction time (DRT). Repeated testing within subjects over 2–8 years also showed age-related slowing across decades. Cross-sectional studies have been criticized for overestimating the actual age-related slowing found in longitudinal analysis. However, this was not the case in the present research. Similar effects were observed in analyses of data from all subjects on their first visit (n = 1318 subjects) compared to data from all subjects over all of their visits (n = 3855 subject visits) compared to data from only those subjects across decades who were tested repeatedly over at least 8 years (n = 314 subjects X 5 visits = 1570 subject visits). Findings from this research have human factors implications for task design, personnel selection, performance prediction, accident analysis, human tests and measurements, and demographic norms, to mention a few.