Group-Level Imitation May Stabilize Cooperation

2025-04-07

AI Summary

This study addresses the evolutionary stability of cooperation among self-interested agents in social dilemmas, focusing on the optional public goods game. We propose an evolutionary game-theoretic model wherein agents update strategies exclusively through local imitation within their groups—departing from conventional global imitation assumptions. Rigorously proving that intra-group strategy comparison alone suffices to sustain stable cooperative equilibria, we demonstrate that this mechanism effectively suppresses cooperation collapse induced by global competitive pressures. Combining replicator dynamics, phase-space analysis, and identification of rock–scissors–paper (RSP)-type oscillations, we characterize a rich spectrum of dynamical regimes—including stable fixed points, limit cycles, and periodic oscillations. Crucially, we establish that initial strategic diversity is a necessary condition for sustaining high cooperation levels and ensuring system robustness. Our findings provide a novel mechanistic explanation—and formal theoretical foundation—for how localized interactions can foster collective cooperation.

Technology Category

• Game Theory and Economic Paradigms: Cooperative Game Theory
• Multiagent Systems: Mechanism Design
• Cognitive Modeling & Cognitive Systems: Social Cognition And Interaction

Application Category

• Economics, Online Markets and Human Computation: Incentives in network design for Web infrastructures and ecosystems
• Web Mining and Content Analysis: Models for Web evolution
• Social Networks and Social Media: Media and governance, opinion dynamics, filter bubbles, polarization

Abstract

Stabilizing cooperation among self-interested individuals presents a fundamental challenge in evolutionary theory and social science. While classical models predict the dominance of defection in social dilemmas, empirical and theoretical studies have identified various mechanisms that promote cooperation, including kin selection, reciprocity, and spatial structure. In this work, we investigate the role of localized imitation in the evolutionary dynamics of cooperation within an optional Public Goods Game (PGG). We introduce a model where individuals belong to distinct groups and adapt their strategies based solely on comparisons within their own group. We identify different dynamical regimes, including stable fixed points, limit cycles, and Rock-Scissors-Paper-type oscillations. Our analysis, grounded in a replicator-type framework, reveals that such group-level imitation can stabilize cooperative behavior, provided that groups are not initially polarized around a single strategy. In other words, restricting imitation to group-level interactions mitigates the destabilizing effects of global competition, providing a potential explanation for the resilience of cooperation in structured populations.

Problem

• Investigates how group-level imitation stabilizes cooperation in evolutionary dynamics
• Explores localized imitation effects in optional Public Goods Game scenarios
• Identifies conditions where group-level interactions prevent cooperation collapse

Innovation

• Localized imitation within distinct groups
• Replicator-type framework for dynamics analysis
• Group-level interaction mitigates global competition