Cooperation and the in-group-out-group bias: A field test on Israeli kibbutz members and city residents

The in-group-out-group bias is among the most widely documented and analyzed phenomenon in the social sciences. We conduct field experiments to test whether the bias extends to the cooperative behavior of one of the most successful modern collectives, the Israeli kibbutz. Despite their promise as universal cooperators, kibbutz members are more cooperative toward anonymous kibbutz members than they are toward anonymous city residents. In fact, …