Whether or not to punish a defector.

Payoffs to punishers and non-punishers when with a defector in a group of three. Payoffs are shown for the row player only. p is the cost of carrying out one unit of punishment and s is the benefit an individual receives when any group member punishes. This benefit is assumed to arise from defectors switching to cooperating after being punished. Provided s>p punishment pays. In (a) each act of punishment has an additive effect on the benefits arising, whereas in (b) punishing when another individual is already punishing brings no additional benefit.当三人博弈组中存在背叛者（defector）时，惩罚者（punisher）与非惩罚者（non-punisher）的收益分布。本数据集仅展示行参与者（row player）的收益数据。其中p为实施一单位惩罚所需承担的成本，s为任意群体成员实施惩罚时，个体可获得的收益。该收益假设源于背叛者在受到惩罚后转向合作的行为。当s>p时，实施惩罚具备收益优势。在(a)情境中，每一次惩罚行为对所产生的收益均具有叠加效应；而在(b)情境中，若已有其他个体实施惩罚，后续惩罚将不会带来额外收益。