Repetition errors in habitual prospective memory: elimination of age differences via complex actions or appropriate resource allocation.

A challenge in habitual prospective memory tasks (e.g., taking medication) is remembering whether or not one has already performed the action. Einstein, McDaniel, Smith, and Shaw (1998, Psychological Science, 9, 284) showed that older adults were more likely to incorrectly repeat an action on habitual prospective memory tasks. Extending this research, we (a) biased participants either toward repetition or omission errors, (b) investigated whether performing a more complicated motor action can reduce repetition errors for older adults, and (c) examined participants' resource allocation to the prospective memory task. Older adults committed more repetition errors than younger adults regardless of biasing instructions when ongoing task demands were challenging (Experiment 1). Performing the more complex motor action, however, reduced repetition errors for older adults. Further, when the ongoing task was less demanding, older adults' repetition errors declined to levels of younger adults (Experiment 2). Consistent with this finding, the resource allocation profiles suggested that older participants were monitoring their output (prospective memory execution) in each trial block.