Emotional events induce retrograde memory impairments on conceptually-related neutral events.

Emotional events are known to be prioritized during episodic encoding, leading to more detailed recollections compared to neutral events. Encoding an emotional event can influence the mnemonic fate of preceding or subsequent neutral events. Studies examining the impact of emotion on memory for neighboring neutral events have produced inconsistent results, which could be due to differences in the conceptual association between emotional and neutral stimuli. To test this idea, we conducted two behavioural experiments in which participants viewed one neutral and one emotional video clip from the same television series (Bates Motel) or from two different sources (emotional video from Bates Motel, neutral video from An Education). In both experiments, we manipulated the order in which participants viewed the videos - one group viewed the neutral video before the emotional video and the other group viewed the neutral video after the emotional video - and tested memory for all videos using free recall. We found that encoding a neutral video before, but not after an emotional video impaired recall, illustrating a retrograde impairment. Critically, this impairment only occurred when the videos were conceptually related, as in Experiment 1. In contrast, there was no indication of a retrograde impairment when the videos were not related, as in Experiment 2. Thus, a conceptual relationship is crucial for emotional events to imbue a retrograde impairment on neutral event memory.