Consistent and inconsistent performance in young and elderly adults

Nineteen young adults and 20 nondemented elderly adults participated in simple reaction time (SRT) and choice reaction time (CRT) tasks that vary in processing demands. SRT standard deviation was operationally defined as Consistency, creating a continuum of performance consistency ranging from low consistency (Lo‐C, large SRT standard deviations) to high consistency (Hi‐C, small SRT standard deviations). The SRT task employed 3 preparatory intervals (1,000, 2,000, 3,000 ms), varied randomly across trials to reduce expectancy effects. The lexical decision task (LDT) contained 120 words and 120 pseudowords. Correlational analyses indicated a relation (especially for the elderly) between SRT and CRT performance and other psychometric and neuropsychological measures of mood, vocabulary ability, and digit symbol substitution. Regression analyses examined the relationship between Age, Consistency, SRT, and LDT performance and these psychometric and neuropsychological variables. Age x Consistency interactions were observed, suggesting an additional mechanism (or mechanisms) for slowing in the elderly beyond performance consistency or inconsistency. Relation to the brain reserve capacity theory (Satz, 1993) is discussed.