Figure 2
In dyadic games, dilemma strength and social efficiency deficit are the two sides of the same coin. (A) Shown is the payoff structure of the Donor-Recipient game, as well as the inverse relationship between dilemma strength and social efficiency deficit. As the latter increases, the former decreases, in which case even a weak incentive in the right direction may overturn defection. (B) Mechanisms of social viscosity may provide the incentive necessary to overturn defection. One such mechanism is network reciprocity, which modifies the payoff structure of the Donor-Recipient game by increasing a sucker’s payoff and decreasing the temptation payoff by an amount H. The quantity H increases with social efficiency deficit and decreases with the average number of neighbours in a network, k. Consequently, when k is sufficiently small, increasing social efficiency deficit may lower dilemma strength to zero, thus overturning defection and establishing cooperation. (C) Unlike all variants of the Prisoner’s Dilemma, including the Donor-Recipient game, which abhor the exploitation of cooperators by defectors, the Chicken game abhors mutual defection. Yet, the inverse relationship between dilemma strength and the social efficiency deficit remains qualitatively the same as before.
