Cooperation transitions in social games induced by aspiration-driven players

TL;DR

This paper investigates how aspiration-driven strategy updates influence cooperation in social games, revealing phase transitions and conditions that favor cooperation, contrasting with imitation-based dynamics, supported by theoretical and simulation results.

Contribution

It introduces a comprehensive model of aspiration-driven strategy updating, analyzing its effects on cooperation transitions, and compares it with imitation mechanisms in social game dynamics.

Findings

Continuous and abrupt cooperation transitions identified.

Strong selection can lead to multiple steady states or trapping.

Aspiration-driven updates promote cooperation in Prisoner Dilemma.

Abstract

Cooperation and defection are social traits whose evolutionary origin is still unresolved. Recent behavioral experiments with humans suggested that strategy changes are driven mainly by the individuals' expectations and not by imitation. This work theoretically analyzes and numerically explores an aspiration-driven strategy updating in a well-mixed population playing games. The payoffs of the game matrix and the aspiration are condensed into just two parameters that allow a comprehensive description of the dynamics. We find continuous and abrupt transitions in the cooperation density with excellent agreement between theory and the Gillespie simulations. Under strong selection, the system can display several levels of steady cooperation or get trapped into absorbing states. These states are still relevant for experiments even when irrational choices are made due to their prolonged relaxation times. Finally, we show that for the particular case of the Prisoner Dilemma, where defection is the dominant strategy under imitation mechanisms, the self-evaluation update instead favors cooperation nonlinearly with the level of aspiration. Thus, our work provides insights into the distinct role between imitation and self-evaluation with no learning dynamics.