Episodic memories are contextual experiences ordered in time. Despite knowing its adaptive nature, whether our memories for events can be altered in time is not adequately addressed. The role of prediction errors (PEs) in strengthening declarative memory is well established but has not been investigated in the time dimension of episodic memory. We tested this dual possibility out using a 3-day movie viewing paradigm, wherein memorized events are subjected to expectation violations and later tested for sequence memory. Our results revealed that contextual PEs fundamentally weaken the older memorized sequence of mispredicted events. Interestingly, the newer events having the PEs in them had comparable memory strength as control events with repeated viewings but without having any PEs. A hierarchical drift-diffusion model indicated that a change in decision criterion rather than drift rate accounted for the behavioral measures of memory strength. In summary, these results suggest that the temporal arrangement of naturalistic episodic memories are reorganized by contextual prediction errors.
bioRxiv Subject Collection: Neuroscience