Spite

In fair division problems, spite is a phenomenon that occurs when a player's value of an allocation decreases when one or more other players' valuation increases. Thus, other things being equal, a player exhibiting spite will prefer an allocation in which other players receive less than more (if more of the good is desirable). In fair division problems, spite is a phenomenon that occurs when a player's value of an allocation decreases when one or more other players' valuation increases. Thus, other things being equal, a player exhibiting spite will prefer an allocation in which other players receive less than more (if more of the good is desirable). In this language, spite is difficult to analyze because one has to assess two sets of preferences. For example, in the divide and choose method, a spiteful player would have to make a trade-off between depriving his opponent of cake, and getting more himself. Within the field of social evolution, spite is used to describe those social behaviors that have a negative impact on both the actor and recipient(s). Spite can be favored by kin selection when: (a) it leads to an indirect benefit to some third party that is sufficiently related to the actor (Wilsonian spite); or (b) when it is directed primarily at negatively related individuals (Hamiltonian spite). Negative relatedness occurs when two individuals are less related than average. The iterated prisoner's dilemma provides an example where players may 'punish' each other for failing to cooperate in previous rounds, even if doing so would cause negative consequences for both players. For example, the simple 'tit for tat' strategy has been shown to be effective in round-robin tournaments of iterated prisoner's dilemma.