Opposite effects of emotion and event segmentation on temporal order memory and object-context binding

Our daily lives unfold continuously, yet our memories are organised into distinct <i>events</i>, situated in a specific context of space and time, and chunked when this context changes (at <i>event boundaries</i>). Previous research showed that this process, termed <i>event segmentation</i>, <i>enhances</i> object-context binding but <i>impairs</i> temporal order memory. Physiologically, peaks in pupil dilation index <i>event segmentation</i>, similar to emotion-induced bursts of autonomic arousal. Emotional arousal also modulates object-context binding and temporal order memory. Yet, these two critical factors have not been systematically studied together. To address this gap, we ran a behavioural experiment using a paradigm validated to study event segmentation and extended it with emotion manipulation. During encoding, we sequentially presented greyscale objects embedded in coloured frames (colour changes defining <i>events</i>), with a neutral or aversive sound. During retrieval, we tested participants’ memory of temporal order memory and object-colour binding. We found opposite effects of emotion and event segmentation on episodic memory. While event segmentation enhanced object-context binding, emotion impaired it. On the contrary, event segmentation impaired temporal order memory, but emotion enhanced it. These findings increase our understanding of episodic memory organisation in laboratory settings, and potentially in real life with perceptual changes and emotion fluctuations constantly interacting.