Negative emotional events retroactively disrupt semantic scaffolding of temporal memory

Emotional responses pervade everyday life and exert temporally extended effects on cognition. Prior work shows that these modulatory effects of emotion on memory are highly selective, with semantic overlap helping to determine which nearby neutral details are prioritized in long-term memory. Although this has been demonstrated in item recognition, less is known about how emotion interacts with semantic information to influence temporal memory. Here, we developed an emotional oddball task in which participants encoded lists of neutral words that were either semantically related to or unrelated to a perceptually deviant emotional or neutral oddball word. We hypothesized that an adaptive memory system should selectively enhance temporal order and recall memory for information that precedes or follows a conceptually related emotional stimulus. We found that order memory was enhanced for word pairs that preceded a semantically related neutral oddball, suggesting that semantics helps to scaffold temporal encoding processes. By contrast, emotional oddballs retroactively disrupted this mnemonic benefit of semantic overlap on temporal memory. Emotional oddballs also led to proactive impairments in order memory irrespective of semantic relatedness. After a 24-hr delay, emotion enhanced recall of preceding, semantically unrelated words. Encountering an emotional oddball also enhanced recall for subsequent words irrespective of semantic relatedness. Our findings suggest that emotion bidirectionally and selectively disrupts the temporal organization of memory, while also enhancing memory for individualized, unrelated elements of an emotional episode.