Group size effects in social dilemmas: A review of the experimental literature and some new results for one-shot N-PD games

Abstract

It is often argued that group size has negative effects on cooperative behavior in social dilemmas. However, this widely accepted view does not accurately reflect the findings of the experimental research. This paper presents an updated review of the experimental findings on group size effects in various social dilemmas. Also, new results concerning group size effects in the one-shot Prisoner’s Dilemma game are presented. The findings from the review and the experiment suggest that the effects of group size depend on the type of the game as well as on the experimental setting. While group size effects appear in infinitely iterated PD-type games, they do not affect the level of cooperation in the one-shot Prisoner’s Dilemma game. Reasons for the observed differences and the factors that drive the group size effect are discussed.