Abstract: Group bias–the tendency to favor one’s own group (in-group) over other groups (out-groups)–is a widespread phenomenon across cultures. Such bias can lead to serious intergroup conflicts with substantial material and emotional costs. Despite its prevalence, the cognitive and neural mechanisms underlying group bias remain underexplored. We hypothesize that individuals assign different subjective values to in-group versus out-group outcomes, weighting in-group benefits more strongly. To test this, the project comprises five complementary studies. Study 1 aims to determine whether there is a difference in the calculation of the subjective value of the benefits of the in-group and the out-group and whether there is an individual difference in the calculation of the subjective value of the in-out-group. Study 2 aims to build a computational model that can accurately describe the representation of in-group and out-group values and establish a model that can accurately predict group cooperation and conflict.  Study 3 will use brain imaging technology to identify the key brain regions encoding in-group and out-group interests and reveal the computational neural mechanism of subjective value representation of in-group and out-group interests. Subsequently, Study 4 will explore how individual subjective value for internal and out-group influences cooperation and intergroup conflict behavior. Finally, Study 5 will investigate whether the neurohormone oxytocin can modulate in-group vs. out-group value computation, with the goal of enhancing intergroup cooperation and reducing conflict. Overall, this project will deepen our understanding of the cognitive and neural bases of group bias and inform novel interventions (e.g., oxytocin administration) to mitigate intergroup conflict and foster cooperation. The insights gained will be valuable for both advancing social neuroscience theory and improving intergroup relations in society.

Key words: Intergroup Bias, Subjective Value Computation, Functional Magnetic Resonance Imaging (fMRI), Intergroup conflict, Oxytocin