The tragedy of the commons revisited: the importance of group decision-making

We use a laboratory experiment to compare the way groups and individuals behave in aninter-temporal common pool dilemma. The experimental design distinguishes between anon-strategic problem where players (individuals or groups of three) make decisions withoutinteraction and a strategic part where players harvest from a common pool. This allows us tocorrect for differences between individuals and groups in the quality of decisions whentesting for differences in competitiveness. The results show that groups are less myopic thanindividuals (i.e., they make qualitatively better decisions) but that they are more competitivethan individuals when placed in a strategic setting. The net result is that groups make lessefficient decisions in the strategic game than individuals do. We are able to show that this iscaused by the median voter departing from her original preference in early periods with ashrinking pool (our groups decide by majority rule).