Individual and collective gains from cooperation and reciprocity in a dynamic-network Prisoner's Dilemma driven by extraversion, openness, and agreeableness

2026-07-25

AI Summary

This study investigates how stable personality differences shape the evolution of cooperation in dynamically rewiring social networks. By constructing a repeated prisoner’s dilemma model on an endogenous network, it pioneers the mapping of Big Five traits—specifically extraversion, openness, and agreeableness—onto continuous, localized interaction mechanisms that jointly govern agents’ cooperative decisions and tie adjustments based on initial cooperative inclinations and partners’ behavioral histories. Agent-based simulations coupled with dynamic network analysis reveal that a “cooperate-first, then reciprocate” strategy substantially enhances system-wide fairness, prosperity, and security. Agreeableness fosters cooperation when informed by interaction history, extraversion amplifies environmental influences, and highly agreeable individuals exhibit pronounced assortative linking under high-cooperation conditions.

Abstract

How do stable personality differences shape cooperation when social ties can form and dissolve? We model a repeated Prisoner's Dilemma on an endogenous network in which three continuous Big Five traits map to transparent local mechanisms: Extraversion sets a target number of partners, Openness determines how broadly agents search beyond friends-of-friends, and Agreeableness sets a baseline willingness to cooperate. At each encounter, agents combine this baseline with the partner's directly observed history; there are no trait labels, gossip, or global reputations. Ties form when agents are under-connected and are cut when they become over-connected, with cuts prioritising partners who have defected more often. We vary network size (N=30--200), population composition, and the balance between trait-driven and history-driven behaviour. Three robust patterns emerge. First, cooperate first, then reciprocate---high initial willingness to cooperate combined with history-sensitive response---produces systems that are simultaneously more prosperous, fairer, and safer. Second, personality has predictable conditional effects: Agreeableness helps when history matters but hurts when behaviour is mostly trait-driven; Extraversion amplifies the environment; Openness has little net payoff effect. Third, the network reorganises accordingly: degree assortativity stays near zero, whereas agreeable agents increasingly connect to one another when cooperation takes hold.

Problem

• cooperation
• personality traits
• dynamic networks
• Prisoner's Dilemma
• reciprocity

Innovation

• dynamic network
• personality traits
• Prisoner's Dilemma
• endogenous network formation
• reciprocity