Impact of conformity on the evolution of cooperation in the prisoner’s dilemma game

We present an evolutionary model of the prisoner’s dilemma game taking into account two cognitive mechanisms: (1) payoff-biased strategy transmission and (2) a conformity mechanism involving a tendency to copy the most frequent nearby strategy in a group. Moreover, for two types of conformity, a minority mechanism and a majority rule, a dual process holds whereby the types differ in both the factors that give rise to them and the effects they have. By contrast, a signal process suggests that differences between the two forms of influence are primarily of degree and that fundamental processes are at work in both. We explore the model using both well-mixed and spatially structured populations. When the temptation to defect is low and both conformism and local interactions are present, the system can reach high levels of cooperation or even a full cooperation state. Furthermore, we find a stronger effect of conformity and a higher level of cooperation among the population regardless of the group size. This indicates that conformity follows a signal process. However, when the temptation to defect is rather large, results for the minority influence change non-monotonically with conformism cohesion. This is remarkably different from the results under majority rule, which is considered as support for the dual process.