The evolution of trust and trustworthiness

TL;DR

This paper investigates how trust and trustworthiness evolve across different network structures using the trust game, revealing that network topology generally has limited impact, with specific conditions allowing trust to develop independently of trustworthiness.

Contribution

It provides a comprehensive analysis of trust and trustworthiness evolution across various network types, highlighting unique conditions in scale-free networks where trust can evolve without trustworthiness.

Findings

Trust rarely evolves in well-mixed, lattice, and random networks.

Trustworthiness can evolve depending on game parameters and dynamics.

Scale-free networks can support the evolution of trust independently of trustworthiness.

Abstract

Trust and trustworthiness form the basis for continued social and economic interactions, and they are also fundamental for cooperation, fairness, honesty, and indeed for many other forms of prosocial and moral behavior. However, trust entails risks, and building a trustworthy reputation requires effort. So how did trust and trustworthiness evolve, and under which conditions do they thrive? To find answers, we operationalize trust and trustworthiness using the trust game with the trustor's investment and the trustee's return of the investment as the two key parameters. We study this game on different networks, including the complete network, random and scale-free networks, and in the well-mixed limit. We show that in all but one case the network structure has little effect on the evolution of trust and trustworthiness. Specifically, for well-mixed populations, lattices, random and scale-free networks, we find that trust never evolves, while trustworthiness evolves with some probability depending on the game parameters and the updating dynamics. Only for the scale-free network with degree non-normalized dynamics, we find parameter values for which trust evolves but trustworthiness does not, as well as values for which both trust and trustworthiness evolve. We conclude with a discussion about mechanisms that could lead to the evolution of trust and outline directions for future work.