Are People Conditionally Cooperative? Evidence from a Public Goods Experiment

We investigate to what extent contribution decisions to a public good depend on the contributions of others. We employ a novel experimental technique that allows us to elicit people's willingness to be conditionally cooperative, i.e., to contribute more to the public good the more the other beneficiaries contribute. We find that about a third of subjects' contribution schedules is characterized by complete free-riding. However, a majority of 50 percent of the subjects displays conditional cooperation. Our results can explain why in most repeated public goods experiments subjects initially cooperate while towards the final periods cooperation declines to very low levels.