Illusions of efficacy: The effects of group size on perceived efficacy in social dilemmas

Several theorists have suggested that group members feel a diminished sense of self-efficacy in larger groups facing social dilemmas. Four experiments were performed to explore this question. In Experiment 1 it was demonstrated that group members correctly perceive that self-efficacy declines with group size for step-level public goods problems. In Experiments 2 and 3, group size was objectively unrelated to the subjects' impact on the group's chances for obtaining a public good. But in both experiments, subjects still felt more self-efficacious when the group was smaller. A final experiment explored the relationship between group size and perceived collective efficacy for obtaining a public good. When the provision point was relatively low (viz., one-third of the group had to contribute to provide the public good), subjects generally perceived smaller groups to be more efficacious than larger groups, even though under certain conditions precisely the opposite was true. These illusions of efficacy were attributed to familiar judgmental heuristics, involving an overgeneralization of experience in groups of varying sizes. Their implications for cooperative behavior in social dilemmas are discussed.