Timing of reward cues alters the interaction between reward and interest on memory over time

Extrinsic reward and intrinsic motivation jointly influence memory. While studies show that rewards diminish the effect of intrinsic motivation on memory, rewards usually precede intrinsic motivation, leaving a gap in understanding their interaction when rewards are presented afterward. So, this study investigated how the timing of reward cues moderated the interaction between reward and intrinsic motivation on memory over time. Participants viewed film clips, rated interest, and completed memory tests at different delays. Reward cues were presented either before or after each clip and rating. Results showed that when cued before clips, rewards improved memory and attenuated forgetting for low-interest clips, thereby decreasing the interest effect on memory. Conversely, when cued after clips, rewards improved memory and attenuated forgetting for high-interest clips, thereby increasing the interest effect. Both patterns emerged through time-dependent consolidation. These findings clarify how extrinsic reward and intrinsic motivation interact across temporal dynamics to influence memory.