We analyze the interplay between cooperation norms and people's punishment behavior in a social-dilemma game with multiple punishment stages. By combining multiple punishment stages with self- contained episodes of interaction, we are able to disentangle the e ects of retaliation and norm-related punishment. An additional treatment provides information on the norms bystanders use in judging punish- ment actions. Partly con rming previous ndings, punishment behavior and bystanders' opinions are guided by an absolute norm. This norm is consistent over decisions and punishment stages and requires full contributions. In the rst punishment stage, our results suggest a higher personal involvement of punishers, leading to a non-linearity de ned by the punishers' contribution. In later punishment stages, the personal-involvement e ect vanishes and retaliation kicks in. Bystanders generally apply the same criteria in all stages, also favoring retaliation in response to harsh punishment actions.
