# Social Pressure and Environmental Effects on Networks: A Path to Cooperation

## TL;DR

This study investigates how social pressure and environmental factors influence cooperation in networks, using a modified Prisoner's Dilemma model to analyze the effects of vigilant neighbors on individual payoffs across different conditions.

## Contribution

It introduces a model where vigilance reduces temptation to defect, exploring its robustness across topologies and update rules through extensive simulations and theoretical insights.

## Key findings

- Vigilance promotes cooperation under certain network conditions.
- The effectiveness of social pressure varies with topology and initial states.
- Robustness of cooperation depends on environmental and evolutionary parameters.

## Abstract

In this paper, we study how the pro-social impact due to the vigilance by other individuals is conditioned by both environmental and evolutionary effects. To this aim, we consider a known model where agents play a Prisoner's Dilemma Game (PDG) among themselves and the pay-off matrix of an individual changes according to the number of neighbors that are "vigilant", i.e., how many neighbors watch out for her behavior. In particular, the temptation to defect decreases linearly with the number of vigilant neighbors. This model proved to support cooperation in specific conditions, and here we check its robustness with different topologies, microscopical update rules and initial conditions. By means of many numerical simulations and few theoretical considerations, we find in which situations the vigilance by the others is more effective in favoring cooperative behaviors and when its influence is weaker.