Error analysis of delayed response in aged squirrel monkeys

Abstract

Young adult and aged squirrel monkeys were tested on variations of a two-choice, spatial delayed-response task. Aged monkeys committed more errors than did young monkeys. However, the diminished accuracy of the aged monkeys was not attributable to a memory deficiency because the difference was independent of delay interval. Aged monkeys did not display less responsesequence variability and were no more likely to commit systematic errors than were young monkeys. When response accuracy decreased as a result of increased delay intervals, or absence of a predelay cue, both age groups increased the proportion of errors attributable to random responding; however, the proportion of errors attributable to systematic errors either decreased or remained constant. © 1989 Psychonomic Society, Inc.