Time of day effects on the use of distraction to minimise forgetting

Recent research found that implicit rehearsal of distraction can reduce forgetting for older adults, in part due to their inefficient regulation of irrelevant information. Here, we investigated whether young adults' memory can also benefit from critical information presented as distraction. Participants recalled a list of words initially and then again after a 15-min delay, with some of the critical studied words exposed as distraction during the delay. We tested young adults at an optimal versus non-optimal time of day, the latter a condition intended to mirror patterns of those with reduced attention regulation. We also varied task instruction to assess whether awareness of an upcoming memory task would influence implicit rehearsal of distraction. The task instruction manipulation was ineffective, but desynchronising time of testing and period of optimal cognitive arousal resulted in a memory benefit. Young adults tested at a non-optimal time showed minimal forgetting of words repeated as distraction, while those tested at an optimal time showed no memory benefit for these items, consistent with research suggesting that attention regulation is greatly affected by circadian arousal.