Cognitive reappraisal influences the organization of emotional episodes in memory.

Changes in our environment help to segment continuous experience into distinct memories. For example, switching locations can cue this segmentation process and enhance long-term memory. Experiencing a wave of negative emotion can also separate memories of adjacent events, but it remains unclear whether this effect is similarly adaptive. Here, we tested whether downregulating emotional responses alters the impact of negative emotion on memory organization and whether emotion-driven segmentation is related to mental health. Participants viewed sequences of neutral objects interspersed with a single negative image and were cued to either reappraise their emotional responses or passively experience them. As expected, viewing negative images elicited segmentation, characterized by changes in temporal memory. Contrary to our hypothesis, reappraisal led to memory segmentation but in a different way: greater reductions in negative affect were associated with stronger memory separation. Across individuals, mood predicted which segmentation style prevailed, with less positive moods favoring emotion-driven memory separation. Pupillometry further revealed two distinct features of pupil dilation to negative images: one associated with passive exposure and the other with cognitive reappraisal. This latter cognitive component peaked rapidly after the negative image, suggesting that participants engaged regulatory strategies to structure their memories. Finally, individuals who showed a stronger tendency to segment memories under intense emotion also exhibited higher pupil-linked emotional arousal and reported more symptoms of posttraumatic stress disorder. These findings suggest that emotional memories can be segmented by competing cognitive and affective pathways, with a bias toward emotion-driven segmentation linked to poorer mental health.