Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
The expectation that non-cooperators will be punished can help to sustain cooperation, but there are competing claims about whether opportunities to engage in higher-order punishment (punishing punishment or failure to punish) help or undermine cooperation in social dilemmas. Varying treatments of a voluntary contribution experiment, we find that availability of higher-order punishment opportunities increases cooperation and efficiency when subjects have full information on the pattern of punishing and its history, when any subject can punish any other, and when the numbers of punishment and of contribution stages are not too unequal.