"In-group love" and "out-group hate" in Conflict Between Groups and Between Individuals

Do people participate in intergroup conflict to help their in-group or to harm the out-group? The \emph{Intergroup Prisoner's Dilemma Maximizing Difference} (IPD-MD) game disentangles individual motivations in intergroup conflict. In this game, members of two groups can contribute to a group effort, with or without harming the other group. Previous findings show that people tend to avoid intergroup conflict by contributing to their in-group without harming the out-group. This observation is surprising, given the \emph{common enemy effect}, by which intergroup conflict increases contributions to the in-group. Recent findings reveal that behavior in intergroup conflict is strongly moderated by whether the conflict is perceived to threaten the individuals in the group or the group as a unity. We manipulate the perceptions of intergroup conflict to find that out-group hate does emerge---only if the conflict is perceived to threaten the group.