Shared effects of one's own and others' experiences during reinforcement learning on episodic memory.

Humans learn not only from their own experiences but also by observing others. Prior research has shown that reward prediction errors (RPEs) - the difference between expected and received outcomes - guide both experiential and observational reinforcement learning. While RPEs from direct experience have been linked to memory formation, it remains unclear whether vicarious RPEs play a similar role in observational learning. Using an incidental memory paradigm, we investigated how experiential and observational learning in a decision-making task shape memory and examined the role of RPEs in this process. Although recognition accuracy did not differ between learning conditions, participants reported higher confidence in memories from experiential trials. Notably, across both learning conditions, gambling and positive RPEs during memory item presentation were associated with enhanced memory. These findings advance our understanding of how observing others' choices and outcomes affects episodic memory by emphasizing shared encoding mechanisms with experiential learning.