We investigate experimentally the underlying motivations and individual dierences with regard to the participation in between-group conflict in nested social dilemmas. In our nested social dilemmas, the collective is divided into two groups, and individuals allocate tokens between a private, a group-specific, and a collective good. We vary the marginal per capita return of the group-specific and collective good in order to manipulate the motivational within- and between group conflicts. A first experiment shows that a between-group conflict leads to within-group cooperation and particularly individuals with positive other-regarding preferences (prosocials) react to a between-group conflict by contributing to the group-specific good. Hence, paradoxically, individuals with positive other-regarding preferences may foster between-group conflicts. A second experiment reveals that prosocials' contributions to the group-specific or collective good vary as a function of the personal costs of within-group versus collective cooperation, supporting the weighted average social preference theory by Charness and Rabin (2002).
between-group conflict local and global public goods nested social dilemma other-regarding preferences