The Impact Of Social Comparison Direction On The Neural Basis Of Reward Processing

Social comparison is a critical psychological context and social comparison with other individuals is a central phenomenon in human societies. How social comparison affects individual well-being is of central importance for understanding behavior in any social environment. Social psychologists asserted that comparing with others is an essential social phenomenon, and others' information more effective than oneself information. Concerned about the relative level, social psychologists claimed that the impact of identical stimulus may vary if situation changes.In daily life, we often find out that people's equity and satisfaction experience will be so different while facing the same reward. Exploring clearly the impact of social comparison on reward processing, there are crucial implications for individual matters and society. Such as, self-evaluations, life satisfaction, patterns of consumption and savings, the design of optimal taxation and redistribution schemes, labor supply and the optimal provision of incentives in firms.Psychology researches revealed that one's emotion experience or individual well-being, whose quality or intensity is influenced not only by its own attributes, but also by the psychological contexts of social comparison direction (upward comparison/Disadvantageous inequity, parallel comparison/Equity, downward comparison/Advantageous inequity). The present two studies focus on social comparison direction and research the reward processing in the social comparison context in two aspects as follows.In study 1, we try to explore the electrophysiological correlates of reward processing in the social comparison context (Social Comparison with the other people by three social comparison directions) on reward processing" and its neural mechanism.In study 2, we further test the impact of "Social Comparison with other two people (by four social comparison directions)" on reward processing and its neural mechanism. In study 1:event-related potentials (ERPs) were recorded to explore the electrophysiological correlates of reward processing in the social comparison context when subjects performed a simple number estimation task that entailed monetary rewards for correct answers. Three social comparison stimulus categories (three relative reward levels/self reward related to the other subject's) were mainly prepared:Self:Other=1:2 (Disadvantageous inequity); Self:Other=1:1 (Equity); Self: Other= 2:1 (Advantageous inequity).In study 2:ERPs were recorded to explore the electrophysiological correlates of reward processing in the complex social comparison context. Four social comparison stimulus categories (four relative reward levels) were mainly prepared:Self:He:She= 1:2:4 (Disadvantageous inequity); Self:He:She= 1:1:1 (Equity); Self:He:She= 4:2:1 (Advantageous inequity); He:Self:She= 1:2:4 (Ambiguous Comparison:worse off than some, better off than many).In study 1:results showed that:both Disadvantageous and Advantageous inequity elicited a more negative ERP deflection (N350-550) than did Equity between 350 and 550 ms, and the generators of N350-550 were localized near in the parahippocampal gyrus and the medial frontal/anterior cingulate cortex, which might be related to monitor and control reward prediction error during reward processing. Then, Disadvantageous and Advantageous inequity both elicited a more negativity (LNC1 and LNC2) than did Equity between 550-750 ms. Generators of LNC1 and LNC2 were both localized near in the caudate nucleus, which might be related to reward processing under social comparison.In study 2:results showed that:Disadvantageous, Advantageous Inequity and Ambiguous Comparison conditions all elicited a more negative ERP deflection (N350-550) than did Equity between 350-550 ms, which might reflect reward prediction error. Then, Ambiguous Comparison, Disadvantageous and Advantageous Inequity all elicited a more ERP deflection than did Equity between 550-750 ms, which might be involved in evaluating the rewards after detection of reward prediction error. Furthermore, Ambiguous Comparison elicited a greater negativity (N550-750) than did Disadvantageous and Advantageous Inequity, and the generator of N550-750 was localized in the caudate nucleus and the anterior cingulate cortex, which might be related to reward processing and cognitive conflict controlling. Last, Disadvantageous Inequity elicited a late more positive ERP component (LPC) than did Advantageous Inequity, Equity and Ambiguous Comparison conditions between 1200-1400 ms. The LPC might reflect strong unpleasant emotional experience.