The difference between punishments and rewards in fostering moral concerns in social decision making

In social decision making, punishing non-cooperation and rewarding cooperation may not only affect cooperation because of instrumental reasons. They may also evoke moral concerns regarding cooperation as they signal that cooperation is socially approved of and non-cooperation socially disapproved of. I argue that punishments do this to a greater extent than rewards as punishments communicate an obligatory rule and rewards communicate a voluntary rule. Indeed, the first experiment shows that, in a social dilemma, the concept of punishment increased cooperation and the concept of a reward did not. The second experiment showed that participants showed more disapproval towards an offender when there was a punishment for non-compliance than when there was a reward for compliance. These findings suggest that punishing non-cooperation more strongly foster moral concerns regarding cooperation than rewarding cooperation. Possible implications for internalizations are discussed.