 One way to make the idea of local interaction more realistic for some applications is to let agents choose the partners with whom to interact, based on payoffs in past interactions. Skyrms 2004 considers iterated PDs among a population of unconditional cooperators and defectors. Initially, as usual, each agent chooses a partner at random from the remaining members of the population. For subsequent interactions, however, the odds of choosing that partner are adjusted, according to either the payoffs from previous times that partner was chosen, or (more realistically) the payoffs from previous times that there has been interaction with that partner (regardless of which one was “chooser”). In a typical PD, where the payoffs for temptation, reward, punishment and sucker are 3, 2, 1 and 0, both cooperators and defectors eventually choose only cooperators. Since the cooperators are chosen by both cooperators and defectors, they play more often than the defectors who play only when they are doing the choosing. If we assume that there is an equal division between cooperators and defectors, then cooperators can expect a return of one reward payoff when they are the chooser, and a fifty/fifty mix of of reward and sucker payoffs when they are the chosen. So their expected payoff for each interaction will be \((3R+S)/2\). Defectors can expect a return of one temptation payoff per play, but they play half as often. With payoff structure indicated, \(3R+S \gt T\), and so cooperators do better, even with this “one-way” association. 