Impact of Trust in the Spatial and Evolutionary Iterated Prisoner’s Dilemma

Abstract

The complex dynamics that shape human interactions have been the object of studies for decades. One of the most famous examples to analyse the cooperative or defective nature of people is the Iterated Prisoner’s Dilemma (IPD), a versatile dynamic game which has been shown capable of capturing the emergence of cooperative behaviours in environments where people are rationally tempted to defect. Trust plays a crucial role in such social interactions, as it intrinsically influences a human on which behaviour to adopt with a partner: a key aspect that the Prisoner’s Dilemma (PD) game fails to register. In this study, two variants of the traditional PD game are proposed in the context of spatial and evolutionary Iterated Prisoner’s Dilemma; each variant features the inclusion of trust as a variable that affects the rewards of the two-player game. The goal of this paper is to study the impact that trust has on the efficacy of traditional Prisoner’s Dilemma strategies played by agents in simulated environments. The results obtained over different experiments confirm that trust indeed fosters cooperating behaviours among agents, and allows them to more easily populate worlds that feature harsh living conditions.