Parallel versus Sequential Update and the Evolution of Cooperation with the Assistance of Emotional Strategies

TL;DR

This paper investigates how the method of updating strategies—parallel versus sequential—affects the evolution of cooperation in networked Prisoner's Dilemma games, emphasizing the role of emotional, sign-dependent strategies.

Contribution

It demonstrates that parallel updating significantly promotes cooperation compared to sequential updating, challenging assumptions in existing models.

Findings

Parallel updating supports cooperation over a wider parameter range.

Sign-dependent strategies catalyze cooperation in coevolving networks.

Sequential updating is less effective in fostering cooperation.

Abstract

Our study contributes to the debate on the evolution of cooperation in the single-shot Prisoner's Dilemma (PD) played on networks. We construct a model in which individuals are connected with positive and negative ties. Some agents play sign-dependent strategies that use the sign of the relation as a shorthand for determining appropriate action toward the opponent. In the context of our model in which network topology, agent strategic types and relational signs coevolve, the presence of sign-dependent strategies catalyzes the evolution of cooperation. We highlight how the success of cooperation depends on a crucial aspect of implementation: whether we apply parallel or sequential strategy update. Parallel updating, with averaging of payoffs across interactions in the social neighborhood, supports cooperation in a much wider set of parameter values than sequential updating. Our results cast doubts about the realism and generalizability of models that claim to explain the evolution of cooperation but implicitly assume parallel updating.