Second-Party and Third-Party Punishment in a Public Goods Experiment

We experimentally investigate whether third-party punishment is more effective than second-party punishment to increase public goods contribution. In our experiment, third parties first played the standard public goods game and then made punishment decisions as independent bystanders. We find that third parties punished more frequently, severely, and less antisocially, resulting in a higher contribution level than that driven by second party punishment. The third party's exaggerated emotion towards free riders is proposed to explain their superior punishment effectiveness