Reward at encoding but not retrieval modulates memory for detailed events

Much of the evidence suggesting that rewards improve memory performance has focused on how explicit rewards facilitate encoding of simplistic stimuli. To expand beyond this focus, the current study tested how explicit rewards presented at encoding as well as retrieval facilitate memory for information contained within complex events. In a single experimental session, participants (N = 88) encoded videos depicting naturalistic events (e.g., getting dressed) and then completed a recognition test probing their memory for different detail types (i.e., event, perceptual, or contextual) from the video stimuli. We manipulated the explicit reward associated with each video, such that accurate memory responses for half the videos were associated with high monetary incentives and half were associated with low monetary incentives. This reward manipulation was presented at either encoding or retrieval during a recognition memory test. The reward manipulation only affected memory when presented at encoding and this effect did not depend on the type of detail probed. Drift Diffusion Modelling further revealed that presenting reward information at encoding engendered greater encoding fidelity-indexed by an increase in drift rate-but did not change response caution at the time of retrieval-indexed by response threshold. Together, our results suggest that presenting reward information when encoding but not retrieving complex events has a general facilitatory effect, likely via attentional processing, on the ability to later remember precise details from the event.