Procedural justice in punishment systems: inconsistent punishment procedures have detrimental effects on cooperation.

The current research examines a moderator who predicts in what situations punishment can have detrimental effects on cooperation. We hypothesized that when a punishment system is perceived as procedurally unfair, people's cooperation level decreases. Results of two experiments indicated that participants cooperated less in a group-based trust game when punishment was inconsistent between persons (i.e. not all group members would be punished for defection) than when punishment was consistent between persons (i.e. any group member who defected would be punished) or when there was no punishment. These effects were mediated by perceived belongingness. The authors conclude that an unfair punishment system leads people to feel marginalized as a group member, and this prompts them to display less cooperation.