Reward Motivation More Consistently Modulates Memory for Younger Compared to Older Adults in a Directed Forgetting Task

Remembering and forgetting are both important processes of a healthy memory system, but both processes can show age-related decline. Reward anticipation is effective at improving remembering in both younger and older adults, but little is known about the effects of incentives on forgetting. In four online experiments, we examined whether reward motivation modulates intentional remembering and forgetting in younger and older adults, and systematically varied the presentation of reward cues during encoding to test whether the temporal dynamics of reward anticipation are important for directed forgetting performance. Both age groups showed directed forgetting effects such that participants remembered more items they were instructed to remember than instructed to forget, but across experiments, we found no evidence that reward incentives improved forgetting in either age group. Younger adults consistently exhibited reward-modulated memory across experiments and varying the timing of the reward cue had little impact on performance. Older adults displayed inconsistent effects of reward on memory, only when reward anticipation was elicited closer to the middle of the experimental trial did it enhance memory in this task. Overall, the findings from the current set of experiments indicate that reward anticipation improved memory, but not forgetting, and most consistently for younger adults, compared to older adults. Further, older adults 'cognitive performance may be more sensitive to the placement and timing of reward anticipation in the experimental trial perhaps due to the time course of reward anticipation and interactions with the hippocampus that may show age-related change. Public Significance Statement Reward motivation has been shown to improve various aspects of cognitive performance, including memory, across the adult lifespan. The ability to intentionally forget is an important aspect of an adaptive memory system. The present set of studies suggests that reward motivation more consistently and selectively modulates memory for younger compared to the older adults but does not help intentional forgetting in either age group.