Emotion and list context modulate the impact of expectation on memory formation

Emotional stimuli are often remembered better than neutral ones, yet the mechanisms behind thisadvantage remain debated. One key factor in memory enhancement is the encoding ofexpectation violations, but their interaction with emotional valence remains poorly understood.This study examined how expectation and emotional content jointly shape recognition memory.Across three experiments, participants first learned predictive contingencies in a rule-learningtask. An encoding phase followed, in which some stimuli violated established expectations, whileemotional content was manipulated orthogonally to expectation. Recognition memory was thentested for expected and unexpected stimuli. In mixed lists (Experiment 1), unexpected stimulienhanced recollection for negative and neutral items but not for positive ones. When arousal wasmatched across valence (Experiment 2), the benefit shifted to unexpected positive and neutralstimuli. In pure emotional lists (Experiment 3), the effect of expectation violations on recollectionwas diminished, and memory was shaped primarily by valence, with negative stimuli elicitinggreater recollection than positive ones. These findings show that the mnemonic benefit ofunexpected events is not uniform but varies with valence, arousal, and list composition. Theysupport layered models of distinctiveness, suggesting that memory emerges from the interactionof item-level expectancy, emotional salience, and contextual variability.