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

Assuming that cooperators and defectors are influenced by peer pressure with a certain probability. The influence mode is that the neighbors who adopts the opposite strategy to the central individual will reduce the fitness of the central individual. This paper explores the impact of peer pressure on the evolution of cooperation in the prisoner’s dilemma game under the condition that the pressure sensitivity of the cooperators and defectors are equal and unequal. The simulation results show that peer pressure can promote cooperation. When the pressure sensitivity of the cooperators and defectors are equal, the influence of pressure sensitivity on the system is non-trivial. According to the value of pressure intensity, evolution of the system can be roughly divided into three categories. When the pressure intensity is weak, the system is not affected by pressure sensitivity and remains in a state of full defection. When the pressure intensity is moderate, the system undergoes a continuous phase transition from full defection to coexistence and then to full cooperation with the increase of the pressure sensitivity. When the pressure intensity is high, the system undergoes a discontinuous phase transition from full defection to full cooperation and even to full defection with the increase of the pressure sensitivity. In addition, when cooperators and defectors have different pressure sensitivities, the cooperation promotion effect is better than that when cooperators and defectors have the same pressure sensitivities. Specifically, cooperation can be promoted or even dominated under lower pressure sensitivity and pressure intensity, which can explain the emergence of cooperation.