Evolutionary prisoner's dilemma games on the network with punishment and opportunistic partner switching

TL;DR

This study explores how punishment and opportunistic partner switching influence cooperation in networked prisoner's dilemma games, revealing that high partner switching frequency promotes cooperation regardless of punishment strength.

Contribution

It demonstrates the combined effects of punishment and partner switching on cooperation, highlighting the importance of social relationship fluidity in evolutionary game dynamics.

Findings

High partner switching frequency promotes cooperation.

Punishers need to be frequent to suppress defectors at low switching.

Cooperators benefit from being referred by defectors rather than avoiding punishment.

Abstract

Punishment and partner switching are two well-studied mechanisms that support the evolution of cooperation. Observation of human behaviour suggests that the extent to which punishment is adopted depends on the usage of alternative mechanisms, including partner switching. In this study, we investigate the combined effect of punishment and partner switching in evolutionary prisoner's dilemma games conducted on a network. In the model, agents are located on the network and participate in the prisoner's dilemma games with punishment. In addition, they can opportunistically switch interaction partners to improve their payoff. Our Monte Carlo simulation showed that a large frequency of punishers is required to suppress defectors when the frequency of partner switching is low. In contrast, cooperation is the most abundant strategy when the frequency of partner switching is high regardless of the strength of punishment. Interestingly, cooperators become abundant not because they avoid the cost of inflicting punishment and earn a larger average payoff per game but rather because they have more numerous opportunities to be referred as a role agent by defectors. Our results imply that the fluidity of social relationships has a profound effect on the adopted strategy in maintaining cooperation.