Revisiting Confusion in Public Goods Experiments

Theories put forth to explain cooperation in public goods experiments usually assume either that subjects cooperate because they do not understand the game’s incentives or that cooperation stems from social motives such as altruism and reciprocity. Recent research by Andreoni (1995) is an important first attempt to distinguish the roles of confusion and social motives in these environments. However, his results leave the relative importance of confusion and social motives in some doubt and shed little light on the nature of the well-known cooperative decay that occurs in multi-round public good games. This paper provides new evidence on confusion and social motives by reporting data from experiments in which some subjects are grouped exclusively with computers in order to eliminate social motives for their contributions. Our analysis suggests that confusion and social motives are responsible for aggregate cooperation in roughly equal proportions, but that cooperative decay is due entirely to reductions in confusion.