The effects of valid and invalid expectations about stimulus valence on behavioural and electrophysiological responses to emotional pictures.

Previous studies have shown that uncertainty about the expected valence of an upcoming stimulus modulates behavioural and neural responses to the stimulus. However, relatively little is known about how invalid emotion expectations (i.e. expecting a positive picture but seeing a negative picture) affect neural and behavioural responses. To investigate this, two experiments were conducted where participants viewed and rated the pleasantness of emotional pictures that were preceded by a cue. In Experiment 1, there were three cue conditions: uncertain, valid and invalid. The uncertain cue did not indicate the valence of the upcoming picture, whereas cues in the valid condition (70% of positive and negative cues) correctly indicated the valence of the upcoming picture. The remaining trials were invalid, where the valence of the picture differed from the expected valence. Behavioural results showed that invalidly cued negative pictures elicited more neutral valence ratings compared to validly cued pictures. In Experiment 2 we replicated the findings of Experiment 1, and in addition found an increased amplitude for the early (400-600 ms) portion of the late positive potential (LPP) for invalidly compared to validly cued pictures. Together, these results show that invalid expectations influence the neural and behavioural processing of subsequently presented emotional pictures, where invalidly cued pictures led to attenuated (i.e., more neutral) emotional responses, and enhanced early LPP amplitude, compared to validly cued pictures.