Cooperative behaviour in kidney donors and transplant candidates on the Prisoner’s Dilemma task

Abstract Interpersonal cooperation is a prerequisite for individual and social well-being, while organ donation has a plethora of moral implications beyond its medical relevance. However, little has been known about whether kidney donors exhibit higher cooperation in morally-laden decisions. Our study aims to fill this gap by comparing cooperation in kidney donors vs. transplant candidates using a computerized Prisoner’s Dilemma task. Participants were presented with dilemmas and were required to cooperate with or defect against a fictional partner (computer). Participants’ degree of cooperation was modulated based on the computer’ strategy (higher/lower cooperation for more reciprocative/conflicting strategies). There was a trend for donors to be faster than transplant candidates. Interestingly, the higher the degree of cooperation following reward, the lower the degree of cooperation following punishment for transplant candidates. The latter were faster when cooperating after reward, but slower when cooperating after punishment. Our findings provide evidence that kidney donors are more decisive with regard to cooperation vs. competition. On the contrary, transplant candidates show a stronger dependence on their partner’s behaviour. Overall, our results suggest that cooperative behaviour differs between kidney donors and transplant candidates, and that the Prisoner’s Dilemma task could provide a suitable tool to study those patterns.