Evolution of conditional cooperation in public good games.

Balaraju Battu,Narayanan Srinivasan

doi:10.1098/rsos.191567

Abstract

Cooperation declines in repeated public good games because individuals behave as conditional cooperators. This is because individuals imitate the social behaviour of successful individuals when their payoff information is available. However, in human societies, individuals cooperate in many situations involving social dilemmas. We hypothesize that humans are sensitive to both success (payoffs) and how that success was obtained, by cheating (not socially sanctioned) or good behaviour (socially sanctioned and adds to prestige or reputation), when information is available about payoffs and prestige. We propose and model a repeated public good game with heterogeneous conditional cooperators where an agent's donation in a public goods game depends on comparing the number of donations in the population in the previous round and with the agent's arbitrary chosen conditional cooperative criterion. Such individuals imitate the social behaviour of role models based on their payoffs and prestige. The dependence is modelled by two population-level parameters: affinity towards payoff and affinity towards prestige. These affinities influence the degree to which agents value the payoff and prestige of role models. Agents update their conditional strategies by considering both parameters. The simulations in this study show that high levels of cooperation are established in a population consisting of heterogeneous conditional cooperators for a certain range of affinity parameters in repeated public good games. The results show that social value (prestige) is important in establishing cooperation.

Highlights

The prehistory of humans was shaped by achieving public goods through cooperation rather than solely depending on selfish interests [1,2,3]
Field studies show that in many social dilemma situations, cooperation is established among conditional cooperators, suggesting that individuals do not imitate strategies of role models solely based on their payoffs [23,24]
We propose that factors (i) and (ii) can provide suitable conditions for the establishment of cooperation among heterogeneous conditional cooperators in repeated public good game (PGG)

Summary

Introduction

The prehistory of humans was shaped by achieving public goods through cooperation rather than solely depending on selfish interests [1,2,3]. In the initial rounds of repeated PGGs with the same agents, a majority of the population donates to the public good. Field studies show that in many social dilemma situations, cooperation is established among conditional cooperators, suggesting that individuals do not imitate strategies of role models solely based on their payoffs [23,24]. (ii) each individual imitates the social behaviour of a role model based on their role model’s prestige and payoff scores, with a certain affinity or bias. We expect that establishment of cooperation crucially depends on these population affinity parameters along with payoff and reputation values of role models. A conditional agent donates to the PGG if and only if the number of donations in the previous round is more than the agent’s CCC. We plotted the distribution of CCC values of the population for different experimental conditions in the 5000th generation

Results

Discussion

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