Tolerant indirect reciprocity can boost social welfare through solidarity with unconditional cooperators in private monitoring

Abstract

Indirect reciprocity is an important mechanism for resolving social dilemmas. Previous studies explore several types of assessment rules that are evolutionarily stable for keeping cooperation regimes. However, little is known about the effects of private information on social systems. Most indirect reciprocity studies assume public monitoring in which individuals share a single assessment for each individual. Here, we consider a private monitoring system that loosens such an unnatural assumption. We explore the stable norms in the private system using an individual-based simulation. We have three main findings. First, narrow and unstable cooperation: cooperation in private monitoring becomes unstable and the restricted norms cannot maintain cooperative regimes while they can in public monitoring. Second, stable coexistence of discriminators and unconditional cooperators: under private monitoring, unconditional cooperation can play a role in keeping a high level of cooperation in tolerant norm situations. Finally, Pareto improvement: private monitoring can achieve a higher cooperation rate than does public monitoring.

Indirect reciprocity with private, noisy, and incomplete information

“…S4). While L6 ("stern") has been found to be particularly successful under public information (18,32,33), our results confirm that this strategy is too strict and unforgiving when information is private and noisy (34)(35)(36).…”

“…While some subjects are best classified as unconditional defectors, others act as unconditional cooperators or use more sophisticated higher-order strategies (11). In agreement with these experimental studies, there is theoretical evidence that some leading-eight strategies like L7 may form stable coexistences with ALLC (36). In SI Appendix, Figs.…”

“…We first explore how different social norms affect the dynamics of reputations, keeping the strategies of all players fixed. To this end, we use the concept of image matrices (34)(35)(36). These matrices record, at any point in time, which reputations players assign to each other.…”

“…How such initial disagreements spread may itself depend on the social norm used by the population. While some norms can maintain cooperation even in the presence of rare disagreements, other norms are more susceptible to deviations from the public information assumption (34)(35)(36)(37). Here, we explore systematically how the leading-eight strategies fare when information is private, noisy, and incomplete.…”

Experimental evidence of selective inattention in reputation-based cooperation

“…On the one hand, most studies on reputation-based cooperation have dealt with assessment rules that share the feature that assessors thoroughly assess each play. On the other hand, some studies 24 , 25 have explored a new assessment rule, termed ‘staying’, that involves selective inattention. In staying, the assessors do not always assess each play.…”