Group formation and cooperation in social dilemmas: A survey and meta-analytic evidence

We survey the growing literature on group formation in the context of three types of social dilemma games: public goods games, common pool resources, and the prisoner's dilemma. The 62 surveyed papers study the effect of different sorting mechanisms - endogenous, endogenous with the option to play the game, and exogenous - on cooperation rates. Our survey shows that cooperators are highly sensitive to the presence of free-riders, independently of the sorting mechanism. We complement the survey with a meta-analysis showing no difference in terms of cooperation between studies implementing an endogenous and exogenous sorting. What is more, we find that it is no more likely for a cooperator to be matched with like-minded partners in endogenously formed groups than in exogenously formed groups. These observations are related. As we show in the survey, the success of a sorting method in matching like-minded individuals and the levels of cooperation are closely interlinked. (C) 2019 Elsevier B.V. All rights reserved.