The role of mind wandering in memory consolidation: a status report

Recent research has shown that memory consolidation (MC) is not only facilitated by sleep, in particular NREM sleep, but also by wakeful resting states. Mind wandering (MW) is a common phenomenon during waking state, especially during rest. The hippocampus is involved in both MC and MW, and both cognitive processes have been associated with hippocampal ripple activity. Therefore, it is an important and obvious question whether MW interacts with MC. To advance understanding of this question, this review briefly describes and discusses relevant studies that have explored the role of MW in MC. The studies included in this review were required to have experimentally investigated MC and measured MW, either through self-report questionnaires or experience sampling. A provisional synthesis suggests that autobiographical thinking and daydreaming negatively impact MC. However, a specific offline state characterized by greater slow oscillation power and decreased task-focus, which suggests increased MW, has been reported to facilitate MC. It remains unclear whether certain MW contents and characteristics - particularly MW about the previously encoded material - support or inhibit MC. More research is needed to clarify this issue. Future investigations should regularly assess whether MW is related to the learned material, ideally using experience sampling. Additionally, aspects such as the temporal orientation, deliberateness and meta-awareness of MW could be relevant to MC. Furthermore, it may be useful to distinguish between on-task focus with and without task-related thoughts, as well as off-task focus with thoughts (MW) and off-task focus without thoughts (mind blanking).