Underdogs make an alliance: The co-experience of rejection promotes cooperation.

Social rejection research has largely focused on the consequences of rejection when individuals experience rejection alone. Yet little is known about the reaction of those co-experiencing rejection. We tested the hypothesis that the co-experience of rejection increases cooperation between the co-experiencers. Three experiments provided supporting evidence for the hypothesis. The participants cooperated more when they co-experienced rejection than when they experienced rejection alone. The need to belong mediated the relationship between those co-experiencing rejection and cooperation. These findings shed light on the factors that initiate the formation of small groups, especially deviant ones.