Is punishment of free riders driven by descriptive social norms of cooperation and punishment? We conduct experiments in which participants interact in a one-shot social dilemma with punishment. We study how punishment of free riders is influenced by behavior among members of a payoff-irrelevant...

Using a series of sender-receiver games, we find that two senders acting together are willing to behave more antisocially towards the receiver than single senders. This result is robust in two contexts: when antisocial messages are dishonest and when they are honest but unfavorable. Our results...