Cooperation is commonly defined as an individual’s choice that benefits both themself and others, in contrast to selfishness, which benefits the individual only. Cooperative behavior is more likely to occur when the benefit to others, discounted as a function of social distance (i.e., social discounting), is higher than the nondiscounted cost of cooperation Rachlin, H. & Locey, M. L. (Behavioural Processes 87, 25-33, 2011). We tested five 2-player prisoner’s dilemma reward matrices with 117 participants, among which both nondiscounted cost and socially discounted benefit varied systematically. Costs and benefits were defined, respectively, as the amount the participant lost and the amount the other player won when the participant cooperated. In global terms, systematically increasing costs and decreasing benefits of cooperation decreased the percentage of participants who cooperated, as predicted. These results suggest that the balance of costs and benefits of cooperation is useful for predicting cooperative behavior in social situations, such as prisoner’s dilemma games.

合作通常被定义为个人的选择，对个人和他人都有利，而自私则只对个人有利。当对他人的收益（作为社会距离的函数而折现）（即社会折现）高于非贴现的合作成本时，更容易发生合作行为。Rachlin，H.＆Locey，ML（Behavioral Processes 87，25-33，2011）。我们测试了五个117个参与者的2人囚徒困境奖励矩阵，其中非折扣成本和社会折现收益都有系统地变化。成本和收益分别定义为参与者损失的金额和参与者合作时其他参与者赢得的金额。在全球范围内，如预期的那样，系统地增加成本并降低合作收益会降低参与合作伙伴的百分比。这些结果表明，合作成本和收益之间的平衡对于预测社交环境（例如囚徒困境游戏）中的合作行为很有用。