Valence and expectation effects shape event-related potentials to probabilistic social-evaluative feedback from putative peers

In everyday life, we receive social evaluative feedback from specific interaction partners that shapes our expectations about future feedback. It has been proposed that feedback processing and expectations are biased toward positive social feedback. However, the neuronal processes underlying biased social feedback processing remain unclear. In the current Event-Related Potentials (ERPs) study, we exposed participants to seemingly real social evaluations from three senders, each providing dichotomous positive or negative feedback on trait adjectives. In reality, feedback contingencies were manipulated with different ratios of positive versus negative feedback (rare 20 vs 80; equal 50 vs 50; frequent 80 vs 20 per cent of all trials). Participants' expectation ratings followed the general feedback ratios, though they indicated higher expectations for positive feedback. A lower probability of feedback increased all investigated ERP components, except the P1. Furthermore, positive versus negative feedback led to relatively more positive amplitudes in the Feedback-Related Negativity (FRN) and Late Positive Potential (LPP) time windows. Interactions between valence and probability were found for exploratory analyses of the Early Posterior Negativity (EPN) and theory-driven analyses of the P3, with specifically increased amplitudes for rare negative feedback compared to rare positive feedback. The results suggest that, even though negative feedback elicited higher prediction-error-related effects in ERPs associated with general surprise responses (P3) and perceptual attentional enhancement (EPN), the LPP, which is related to elaborate processing, integration, and updating, exhibited larger amplitudes for positive feedback, possibly reflecting biased processing of positive feedback. This may be fundamental for maintaining a positively biased self-view.