Wakeful rest benefits memory when materials can be rehearsed

Abstract Wakeful rest is a brief (e.g., 10 minutes), quiet period of minimal stimulation, which has been shown to facilitate memory performance, compared to a distractor task. Researchers have argued that this benefit is driven by automatic consolidation during the wakeful rest period. However, prior studies have not fully ruled out a controlled rehearsal mechanism, which might also occur during wakeful rest. In the current study, we attempted to replicate the wakeful rest effect under conditions that more strictly limit the possibility of rehearsal. Across six experiments, we manipulated parameters of a standard wakeful rest paradigm, including the type of target materials (word lists or abstract shapes), intentionality of encoding (incidental or intentional), and final retrieval delay (immediate or delayed). Additionally, we tested both younger and older adults to test whether these effects are consistent across the adult lifespan. Importantly, we observed the expected wakeful rest memory benefit in recall for verbal targets, which are easily rehearseable, but not for abstract shapes, which cannot be readily rehearsed. This pattern occurred in both younger and older adults. These results place constraints on the generalizability of wakeful rest memory benefits and suggest that the effect may be at least partly driven by rehearsal processes, rather than an automatic consolidation process.