Abstract: Widely regarded as a crucial topic in human society, fairness plays an important role in social decision-making. Economists and psychologists focus on discovering the motivational and cognitive mechanism underlying the fairness norm. Based on recent researches on fairness norm, three core models related to the fairness norms, namely inequity aversion, reciprocity, and emotion models, were summarized. Behavioral and neuroscience studies that are for or against these models were reviewed and compared. Specifically, the functions of those brain regions (the insula and the DLPFC) that are closely linked to social decision-making were discussed. Finally, the authors provided their opinions about future research.

Key words: fairness norm, social decision making, emotion, insula, dorsal lateral prefrontal cortex (DLPFC)