The impact of social identity complexity on intergroup parochial and universal cooperation under different payoff structures and frames

As society evolves, individuals increasingly cooperate with both in-group members and out-group strangers, despite risks such as betrayal. Social identity plays a crucial role in motivating this cooperation, significantly shaping cooperative behavior. This study explores how social identity complexity—arising from the overlapping of multiple social identities—affects intergroup cooperation. Using the Intergroup Parochial and Universal Cooperation (IPUC) game, we examined universal cooperation, weak parochial cooperation, and strong parochial cooperation under different payoff structures—the equal outcomes game (EOG) and the collective incentives game (CIG)—and framing conditions (individual and group frames). The findings reveal that social identity complexity is positively related to universal cooperation and negatively related to strong parochial cooperation. Individuals with high social identity complexity demonstrated higher levels of universal cooperation and lower levels of strong parochial cooperation, particularly within the CIG compared to the EOG. Additionally, individuals with high social complexity showed greater universal cooperation and less strong parochial cooperation in the individual frame compared to the group frame, while those with low social identity complexity exhibited more weak parochial cooperation in the individual frame. These findings suggest that higher social identity complexity fosters intergroup cooperation, with different payoff structures and framing conditions significantly influencing cooperative behavior.