The Impact of Motivation and Task Difficulty on Resource Engagement: Differential Influences on Cardiovascular Responses of Young and Older Adults

This study examined whether the level of cognitive engagement that older adults were willing to invest was disproportionately influenced by the personal implications of their task, as suggested by selective engagement theory. We experimentally altered the personal implications of a task by manipulating participants’ accountability for their performance. Younger (n 50) and older (n 50) adults performed a memory-search task of moderate difficulty but within the capabilities of both age groups. Both physiological (systolic blood pressure responsivity; SBP-R) and subjective (NASA Task Load Index) measures of cognitive effort were assessed across all difficulty levels. The results replicated findings from previous research indicating that older adults must exert more effort than younger adults to achieve the same level of objective performance. Most important, our results showed that older adults were especially sensitive to our accountability manipulation, with the difference in SBP-R between accountability conditions being greater for older than for younger adults. Finally, we found that there was little relation between subjective measures of workload and our physiological measures of task engagement. Together, the results of this study provide continued support for selective engagement theory.