Prior expectation shapes the emotional response to sounds: behavioural and neural correlates

Prior expectations are known to shape perception especially when a stimulus is ambiguous. Bayesian models of cognition posit perception is a precision-weighted combination of top-down and bottom-up information. We consider here affective responses to highly salient stimuli for which a dominant role of bottom-up processing has previously been emphasised. We study how predictions alter the perception of emotional stimuli in a paradigm in which neutral and aversive sounds were preceded by either predictive or non-predictive cues. Cues predicted the type of sound with 100% or 50% probability. Behavioural measures of trial-by-trial expectation and perceived aversiveness were collected before and after stimulus presentation, respectively. We show that prior expectations biased the perceived aversiveness of sounds towards predictions, but only when subjective expectations were considered (as opposed to the objective expectation based on conditional probability). Neural responses were recorded using EEG. During sound processing, we found P3 and LPP components were increased after non-predictive cues, but only for affective stimuli. Time-Frequency results uncovered a role of alpha-beta oscillations in the precision of predictions, as well as in the processing of unexpected stimuli. Our results indicate expectations directly alter the perception of affective stimuli and its processing, and emphasise the importance of behavioural measures to characterize this relationship.