Spontaneous giving and calculated greed

Economic games are used to investigate the cognitive mechanisms underlying cooperative behaviour, and show that intuition supports cooperation in social dilemmas, whereas reflection can undermine these cooperative impulses. Many people are willing to make sacrifices for the common good, but little is known about the cognitive mechanisms that underlie such cooperative behaviour. In economic experiments subjects often contribute cooperatively against what rational self-interest should dictate. This study uses a series of ten varied experimental designs, including both one-shot and repeated games, to establish whether we are intuitively predisposed to cooperate or to act selfishly. And it seems our gut response is to cooperate — but given more time to think the logic of self-interest undermines collective action and we become less generous. Cooperation is central to human social behaviour1,2,3,4,5,6,7,8,9. However, choosing to cooperate requires individuals to incur a personal cost to benefit others. Here we explore the cognitive basis of cooperative decision-making in humans using a dual-process framework10,11,12,13,14,15,16,17,18. We ask whether people are predisposed towards selfishness, behaving cooperatively only through active self-control; or whether they are intuitively cooperative, with reflection and prospective reasoning favouring ‘rational’ self-interest. To investigate this issue, we perform ten studies using economic games. We find that across a range of experimental designs, subjects who reach their decisions more quickly are more cooperative. Furthermore, forcing subjects to decide quickly increases contributions, whereas instructing them to reflect and forcing them to decide slowly decreases contributions. Finally, an induction that primes subjects to trust their intuitions increases contributions compared with an induction that promotes greater reflection. To explain these results, we propose that cooperation is intuitive because cooperative heuristics are developed in daily life where cooperation is typically advantageous. We then validate predictions generated by this proposed mechanism. Our results provide convergent evidence that intuition supports cooperation in social dilemmas, and that reflection can undermine these cooperative impulses.