In-group versus out-group preferences in intergroup conflict: an experiment

In group conflicts, individuals often have diverse preferences, such as maximizing personal payoff, maximizing the group's payoff, or defeating rivals. When these preferences coexist, isolating their impact on conflict outcomes becomes challenging. To disentangle in-group and out-group preferences, we conduct a group contest experiment in which human in-group or out-group players are replaced with historical subjects to maintain strategic similarity. Our study aims to explore (i) the variation in effort in group conflicts due to in-group and out-group preferences and group cohesion, and (ii) how the impact of these preferences changes when the two groups have explicitly different categorical identities. Surprisingly, our results indicate an absence of overall treatment effects on effort levels. However, the presence of in-groups has heightened concerns about individual payoffs. When out-groups are introduced, these concerns are moderated by an additional focus on the group's payoffs. The negative effect of the in-group preferences and the positive effect of the out-group preferences are weaker when group members have a common categorical identity.