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Talk by Dr. Sophie Nolden, Goethe-Univesity Frankfurt

Our cognitive system picks up sequential structures in order to make predictions about future events. Recent studies suggest that these predictions (priors) are contrasted with incoming sensory evidence. In case of a mismatch (prediction error, PE), the memorized sequential structures can be modified in memory. In a series of experiments, we investigated the impact of perceptual shifts and inter-stimulus distance on PE-induced modulations of episodic memories. In a categorization task, participants classified visually presented scenes or objects as indoor/outdoor. Unbeknown to the participants, some of these stimuli were arranged in a partly repeating sequential structure composed of three consecutive stimuli (triplets). Triplets were presented twice, with the third stimuli being replaced by a new one at the second presentation. The categorization task was followed by a surprise recognition task. We hypothesized that, during the categorization task, participants would recognize the beginning of the triplets at the second presentation and predict the third item. Since the third item was eventually not presented, participants should experience a PE that would lead to worse recognition memory of the replaced item. Importantly, we manipulated the category transitions from the second to the third item of the triplet (same category or different categories), hence, there were perceptual repetitions or perceptual shifts e.g., when shifting from objects to scenes (or vice versa). Our results reveled that recognition memory decreased more for perceptual shifts than for perceptual repetitions but only when these shifts were predictable. In addition, increased temporal distance had a major impact on the effect. Our results underline the importance of discussing the role of PE for memory in light of the sequential structures they are embedded in.