Emotional stimuli boost incidental learning through predictive processing.

Extracting regularities and probabilities from the environment is a fundamental and critical ability in an ever-changing surrounding. Previous findings showed that people are highly efficient in learning these regularities and that emotional stimuli are better learned than neutral ones. Yet, the generality and the underlying mechanism of this benefit are poorly understood. Here, participants viewed a stream of images with negative and neutral valence. Unbeknownst, the items recurred in regularity as triplets. Then, to assess learning, a surprised familiarity test was conducted. The results of Experiment 1, using two sets of stimuli, found better statistical learning for negative triplets than for neutral triplets. Experiment 2 revealed similar benefits even when only a single negative item was in the triplet at the second or third position, suggesting the advantage is not cumulative. We speculated that the predictability of the negative items is driving the effect. Consequently, Experiment 3 confirmed that the memory for neutral items preceding negative items was better than for neutral items preceding neutral items. Together, these findings provide novel insights into the mechanism of how the learning of incidental temporal associations is influenced by negative stimuli and the role of predictability in the negative valence benefit.