Negative emotion reduces the temporal compression of events in episodic memory

Recent studies have revealed that the continuous flow of information that characterizes naturalistic events is temporally compressed in episodic memory, so that remembering an event takes less time than the duration of the past episode. However, the specific characteristics of an event that influence its temporal compression in memory remain poorly understood. In the present study, we examined the extent to which the emotional nature of events impacts their rate of compression in memory representations. We conducted two experiments in which participants were instructed to mentally replay a series of videos depicting negative or neutral events. The results showed that the course of emotional events was less compressed in memory than that of neutral events: the time taken to mentally replay a video, relative to the actual video duration, was significantly longer for negative than for neutral videos. In addition, compression rates were predictive of the subjective quality of memory. Taken together, these results suggest that negative emotion increases the sampling rate of the units of experience that represent the course of events, leading to a lower compression of events in memory representations.