Previous research has discovered a curious phenomenon: groups cooperate less than individuals in a deterministic prisoner’s dilemma game, but cooperate more than individuals when uncertainty is introduced into the game. We conducted two studies to examine three possible processes that might...

Previous research has shown an interindividual-intergroup discontinuity effect: intergroup interactions generally lead to less cooperative outcomes than interindividual interactions. We replicated the discontinuity effect in the deterministic prisoners dilemma, but we found that groups were more...