To explain why pre-play communication increases cooperation in games, one refers to a) strategic causes such as efficient communication or reputation effects, and b) changes in the utilities due to social processes. Hitherto experimental support for both explanations is mixed and confounded. Our...

We revisit the phenomenon that group decisions differ systematically from decisions of individuals. Our experiment solicits individual and group decisions from the same subjects in two settings, gift-exchange games and lottery choices. With no deliberation and voting, the group decision is...