Reward-related memory benefits cannot be explained by post-encoding stimulus-related thought

There is an active debate regarding whether rehearsal drives memory benefits associated with awake post-encoding consolidation. In the current study, we manipulated conditions designed to encourage or discourage rehearsal during post-encoding wakeful rest to characterize downstream effects on associative memory in the context of a reward-motivated memory paradigm. To manipulate rehearsal during the post-encoding period, participants in the rehearsal group were explicitly instructed to rehearse high-reward memoranda for 15 min and then completed an incentivized mini-retrieval test. In contrast, participants in the rest group completed an incentivized mini-retrieval test immediately, eliminating the need for post-encoding rehearsal, then were instructed to rest for 15 min. A surprise memory test occurred approximately 24 h later. We found that reward significantly enhanced item memory, replicating a large body of work. Importantly, we found that neither encouraging post-encoding rehearsal nor self-reported time spent thinking about high-reward stimuli during the post-encoding period were related to reward memory enhancements. These findings suggest that explicitly encouraging rehearsal during post-encoding rest cannot fully explain consolidation-related memory benefits, consistent with the notion that spontaneous processes support reward memory benefits on long-term memory.