Targeted Memory Reactivation and Consolidation-Like Processes during Mind-Wandering in Younger and Older Adults

Mind-wandering (MW) is a universal cognitive process that is estimated to comprise [approximately] 30% of our everyday thoughts. Despite its prevalence, the functional utility of MW remains a scientific blind spot. The present study sought to investigate whether MW serves a functional role in cognition. Specifically, we investigated whether MW contributes to memory consolidation-like processes, and if age differences in the ability to reactivate episodic memories during MW may contribute to age-related declines in episodic memory. Younger and older adults encoded paired associates, received targeted reactivation cues during an interval filled with a task that promotes MW, and were tested on their memory for the cued and uncued stimuli from the initial encoding task. Thought probes were presented during the retention (MW) interval to assess participants' thought contents. Across four experiments, we compared the effect of different cue modalities (i.e., auditory, visual) on cued recall performance, and examined both correct retrieval RTs as well as accuracy. Across experiments, there was evidence that stimuli that were cued during the MW task were correctly retrieved more quickly than uncued stimuli and that this effect was more robust for younger adults than older adults. Additionally, the more MW a participant reported during the retention interval, the stronger the cuing effect they produced during retrieval. The results from these experiments are interpreted within a retrieval facilitation framework wherein cues serve to reactivate the earlier traces during MW, and this reactivation benefits retrieval speed for cued items compared with uncued items.