Balancing selfishness and norm conformity can explain human behavior in large-scale prisoner's dilemma games and can poise human groups near criticality

A research agenda for the study of social norm change

Social norms have been investigated across many disciplines for many years, but until recently, studies mainly provided indirect, implicit and correlational support for the role of social norms in driving behaviour. To understand how social norms, and in particular social norm change, can generate a large-scale behavioural change to deal with some of the most pressing challenges of our current societies, such as climate change and vaccine hesitancy, we discuss and review several recent advances in social norm research that enable a more precise underpinning of the role of social norms: how to identify their existence, how to establish their causal effect on behaviour and when norm change may pass tipping points. We advocate future research on social norms to study norm change through a mechanism-based approach that integrates experimental and computational methods in theory-driven, empirically calibrated agent-based models. As such, social norm research may move beyond unequivocal praising of social norms as the missing link between self-interested behaviour and observed cooperation or as the explanation for (the lack of) social tipping. It provides the toolkit to understand explicitly where, when and how social norms can be a solution to solve large-scale problems, but also to recognize their limits. This article is part of the theme issue 'Emergent phenomena in complex physical and socio-technical systems: from cells to societies'.

Quantal response equilibrium for the Prisoner's Dilemma game in Markov strategies

Within the studies of human cooperation, there are gaps that require further investigation. One possible area for growth is developing theoretical concepts which describe high levels of cooperation. In this paper, we present a symmetrical quantal response equilibrium (QRE) in Prisoner’s Dilemma game (PD) constructed in Markov strategies (tolerance to defection and mutual cooperation). To prove the adequacy of the resulting equilibrium, we compare it with the previously found Nash equilibrium in PD in Markov strategies: the QRE converges with the Nash equilibrium that corresponds with the theory. Next, we investigate the properties of QRE in PD in Markov strategies by testing it against experimental data. For low levels of rationality, the found equilibrium manages to describe high cooperation. We derive the levels of rationality under which the intersection between Nash and QRE occurs. Lastly, our experimental data suggest that QRE serves as a dividing line between behavior with low and high cooperation.

Evolutionary advantages of turning points in human cooperative behaviour

Cooperation is crucial to overcome some of the most pressing social challenges of our times, such as the spreading of infectious diseases, corruption and environmental conservation. Yet, how cooperation emerges and persists is still a puzzle for social scientists. Since human cooperation is individually costly, cooperative attitudes should have been eliminated by natural selection in favour of selfishness. Yet, cooperation is common in human societies, so there must be some features which make it evolutionarily advantageous. Using a cognitive inspired model of human cooperation, recent work Realpe-Gómez (2018) has reported signatures of criticality in human cooperative groups. Theoretical evidence suggests that being poised at a critical point provides evolutionary advantages to groups by enhancing responsiveness of these systems to external attacks. After showing that signatures of criticality can be detected in human cooperative groups composed by Moody Conditional Cooperators, in this work we show that being poised close to a turning point enhances the fitness and make individuals more resistant to invasions by free riders.

Transcranial Direct Current Stimulation Altered Voluntary Cooperative Norms Compliance Under Equal Decision-Making Power

Social norms play an essential role in human interactions and the development of the evolution of human history. Extensive studies corroborate that compliance with social norms typically requires a punishment threat as almost always specific individuals have self-interests that tempt them to violate the norm. Neural imaging studies demonstrate that lateral orbitofrontal cortex (LOFC) and right dorsolateral prefrontal cortex (rDLPFC) are activated when individuals decide to increase social norm compliance when punishment is possible. Moreover, rDLPFC is affirmed to be involved in social norm compliance with or without external punishment threats in a series of transcranial direct current stimulation (tDCS) research. However, these neuroscience studies are based on the ultimatum game (UG) in which the decision-making power between the proposer and the responder is unequal, and no studies support the causal relationship between rDLPFC and voluntary cooperative norms compliance among the equal decision-making power of subjects. Whether modulating the excitability of rDLPFC, which plays a role in norm compliance, alters the extent of compliance with voluntary cooperative norms under equal decision-making power and how norms from different types with asymmetric endowment influence compliance remain unknown. The present study aimed to provide evidence of a direct link between the neural and behavioral results through the application of tDCS over rDLPFC on compliance with voluntary cooperative norms under equal decision-making power. Results verified that activating rDLPFC altered voluntary cooperative norms compliance of all our participants and significant effect over different initial endowments was observed. The role of norm.own and norm.other in compliance was changed in the anodal treatment. Findings validate that enhancing the excitability of the rDLPFC using tDCS leads to high compliance in voluntary cooperation and this effect is specific to equal decision-making power rather than unequal decision-making power.