The role of the degree of emotion expression in cooperative evolution

School of Mathematics and Statistics, Guizhou University - 550025, Guiyang, China

Received: 21 September 2025
Accepted: 9 December 2025

Abstract

The impact of emotions triggered by inequality aversion on cooperation is widely acknowledged, with guilt promoting cooperation and envy inhibiting it. Existing research largely focuses on the binary of emotional full revelation or complete concealment. We posit that an individual's emotions are not always fully revealed or completely concealed, and introduce the parameter to measure the degree of emotional expression. We investigate the impact of this dimensional characteristic on cooperation by employing a spatial prisoner's dilemma game model incorporating individual inequality aversion. Simulation results show that emotional expression can enhance the positive effect of guilt and alleviate the negative effect of envy on cooperation. Moreover, considering inter-individual heterogeneity and intra-individual dynamics in emotional expression, we investigate the evolution of emotional expression degrees over time. The results demonstrate that the emotional expression degrees asymptotically converge to 1 over time in both emotional scenarios.