Local reputation, local selection, and the leading eight norms

Shirsendu Podder,Károly Takács,Simone Righi

doi:10.1038/s41598-021-95130-3

Shirsendu Podder, Károly Takács + Show 1 more

Open Access

https://doi.org/10.1038/s41598-021-95130-3

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Abstract

Humans are capable of solving cooperation problems following social norms. Social norms dictate appropriate behaviour and judgement on others in response to their previous actions and reputation. Recently, the so-called leading eight norms have been identified from many potential social norms that can sustain cooperation through a reputation-based indirect reciprocity mechanism. Despite indirect reciprocity being claimed to extend direct reciprocity in larger populations where direct experiences cannot be accumulated, the success of social norms have been analysed in models with global information and evolution. This study is the first to analyse the leading eight norms with local information and evolution. We find that the leading eight are robust against selfish players within most scenarios and can maintain a high level of cooperation also with local information and evolution. In fact, local evolution sustains cooperation under a wider set of conditions than global evolution, while local reputation does not hinder cooperation compared to global reputation. Four of the leading eight norms that do not reward justified defection offer better chances for cooperation with quick evolution, reputation with noise, larger networks, and when unconditional defectors enter the population.

Highlights

Humans are capable of solving cooperation problems following social norms
When populations have access to complete, errorless information, all leading eight norms maintain very high levels of cooperation when initialised in homogeneous populations with unconditional defectors being introduced as mutants roughly once every ten time-steps
Why people cooperate to a large extent with strangers whom they have no direct experience with is a difficult puzzle[32]

Summary

Introduction

Humans are capable of solving cooperation problems following social norms. Social norms dictate appropriate behaviour and judgement on others in response to their previous actions and reputation. Norms guide behaviour (strategic response of cooperation or defection) and judgement of others (reputation) in light of previous actions and of previous judgements[6] Because of the latter element, social norms are the tools of indirect reciprocity that pave the path for cooperation through reputational dynamics. The simplest social norm dictates cooperation if the opponent has a good reputation and assigns good reputation for cooperation This is a binary version of image scoring[7] according to which cooperative/selfish actions either increment/decrement a person’s image score. To address the shortcoming of image scoring in the misclassification of justified defection, the standing social norm was shown to be superior to image s coring[18] According to this social norm, individuals lose good standing by failing to help others in good standing, whereas withholding help from others in bad standing does not damage their standing[19,22]. The behavioural strategies associated to social norms condition action to both own and opponents’ reputation

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