As an essential feature of social groups, social hierarchies influence how people interact in daily life. However, it is unknown how external evaluations from peers at different levels in a social hierarchy influence feedback processing. In the current study, participants were instructed to establish a social hierarchy through a novel stick drawing task. With their status in the social hierarchy manipulated to be in the middle, participants received positive or negative evaluations from superiors and inferiors separately with ERPs signals recorded. Behaviorally, participants rated their happiness highest, and most quickly after receiving positive evaluations from superiors. ERP results showed that P3 amplitude exhibited an interaction between social hierarchy and feedback valence, such that larger P3 amplitude was elicited by positive evaluations from superiors than any other condition, whereas the feedback-related negativity was only sensitive to the difference between high and low social statuses. Moreover, a generalized linear mixed model examining single-trial ERP data showed P3 amplitude correlated with happiness ratings as a function of feedback valence: a significant positive correlation in the positive feedback condition and a significant negative correlation in the negative feedback condition. P3 was also negatively correlated with RT across all conditions. These results demonstrate that brain activity associated with feedback processing predicted participants' emotion ratings and their decision time. Our study provides the first ERP evidence that positive feedback from superiors impacts neural activity related to reward processing differently than positive feedback from those of lower social standing.

Social information has substantial influences on prosocial behavior. In this study, we performed an event-related potential (ERP) experiment to examine the effect of social influence on giving. The participants were allowed to form an initial decision on how much money to donate to a charity provided the program’s average donation amount and to make a second donation decision. Social influence varied in different directions (upward, downward, and equal) by altering the relative donation amount between the average donation amount and the participants’ first donation amount. The behavioral results showed that participants increased their donation amount in the upward condition and decreased it in the downward condition. The ERP results revealed that upward social information evoked larger feedback-related negativity (FRN) amplitudes and smaller P3 amplitudes than in the downward and equal conditions. Furthermore, the pressure ratings, rather than the happiness ratings, were associated with the FRN patterns across the three conditions. We argue that people in social situations are more likely to increase their donations owing to pressure than voluntary altruism. Our study provides the first ERP evidence that different directions of social information evoke different neural responses in time course processing.

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