Recently Press and Dyson have dramatically changed our view on the Prisoner's Dilemma by proposing a new class of strategies that enforce a linear relationship between the two players' scores. Players adopting ‘extortion’ respond with cooperation to cooperation in most cases, defect in other rounds, but respond to defection with defection. In this way, extortion enforces full cooperation of the partner who accedes to it because he profits from doing so. This unbeatable strategy is nevertheless prosocial because it is mostly cooperative and induces cooperation even though it gains most itself. Experiments show that about 40% of humans choose to use extortion in competitive situations or when they have the power to exchange coplayers. On being punished in egalitarian situations, they use a generous strategy.

最近，Press 和 Dyson 提出了一种新的策略，使两个玩家的得分之间存在线性关系，从而极大地改变了我们对囚徒困境的看法。采用“勒索”的玩家在大多数情况下以合作回应合作，在其他回合中背叛，但以背叛回应背叛。通过这种方式，敲诈勒索迫使加入它的合作伙伴充分合作，因为他从中获利。然而，这种无与伦比的策略是亲社会的，因为它主要是合作的，并且即使它自己获得了最大的收益，也会引发合作。实验表明，大约 40% 的人选择在竞争情况下或当他们有能力交换同伴时使用敲诈勒索。在平等主义的情况下受到惩罚时，他们会采取慷慨的策略。