Group Identity Affect Fair Processing Behavior And EEG Studies

Fairness is a very important social norm of human society, a large number of researchers have demonstrated that people really have the social preference of inequality aversion, and the factors of personality and context can influence how people perceive and evaluate the fairness. What’s more, Human society is a aggregate, which includes so many multilevel groups and organizations. Because everybody may be a part of these different groups, we have to make interactions with someone with the same membership or not. Recently, the cognitive neuroscience researches have designed experiments to examine the influence of social distance(e.g., friend vs stranger) on social fairness process. However, as another form of social distance, intergroup relationships still have not been studied fully. This study try to explore the relationship between social identity and social fairness by means of the event-related potentials (ERPs).This study includes two experiment, which attempt to merge Social Identity Theory with Economic Game Theory. We use the Minimal Group Paradigm to control the group memberships of the partners who will complete the Ultimatum Game in the experiments. The purpose of our study is to examine whether there is any difference at the behavioral and neural level when people are interacting with in-group member or with out-group member. The results are as follows:1. With the unfairness of offer increasing, the probabilities of acceptance were decreasing. Comparing with interacting with in-group member, the rejection rate was more high when participants were interacting with out-group member. The effect of social identity on acceptance rate was attributed to the rise in acceptance rates of offer6:4and offer7:3in experiment1, while to the rise in acceptance rates of offer7:3and offer9:1.2. The function between the fairness of offer and offers’reaction time was similar to∩-shaped curve, that is to say, the RT of fair offer was the shortest, and the RT of moderate unfair offer was the longest. The fairness of offer had interaction with with intergroup relationships, namely, the peak of∩-shaped curve was offer7:3when interacting with in-group member, but it was changed into offer6:4when interacting with out-group member in experiment1; And, comparing with in-group member, the RT of moderate unfair offer was more longer when interacting with out-group member in experiment2.3. The accept threshold of offer was more high in out-group interaction than in in-group interaction.4. The peak of N1was more negative in out-group interaction than in in-group interaction.5. The mean amplitude of MFN induced by extreme and moderate unfair offer were more negative than it induced by fair offer; And, the fairness was interacted with intergroup membership, namely, the MFN induced by extreme unfair offer was more negative in in-group interaction than in out-group interaction. Comparing with out-group interaction, the peak of d-MFN were more negative in in-group interaction.6. The mean amplitude of P300induced by fair offer was more positive than it induced by extreme and moderate unfair offer, and there was no significant difference between the latter two.