Cooperation and competition between human players in repeated microeconomic games offer a window onto social phenomena such as the establishment, breakdown and repair of trust. However, although a suitable starting point for the quantitative analysis of such games exists, namely the Interactive Partially Observable Markov Decision Process (I-POMDP), computational considerations and structural limitations have limited its application, and left unmodelled critical features of behavior in a canonical trust task. Here, we provide the first analysis of two central phenomena: a form of social risk-aversion exhibited by the player who is in control of the interaction in the game; and irritation or anger, potentially exhibited by both players. Irritation arises when partners apparently defect, and it potentially causes a precipitate breakdown in cooperation. Failing to model one’s partner’s propensity for it leads to substantial economic inefficiency. We illustrate these behaviours using evidence drawn from the play of large cohorts of healthy volunteers and patients. We show that for both cohorts, a particular subtype of player is largely responsible for the breakdown of trust, a finding which sheds new light on borderline personality disorder.
Bibliographical noteFunding Information:
PRM gratefully acknowledges a Wellcome Principal Research Fellowship; AH and IV are supported by the Principal Research Fellowship of PRM. PD gratefully acknowledges funding by the Gatsby Charitable Foundation. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. We thank Michael Moutoussis for helpful discussions and Tobias Hauser and Michael Moutoussis for comments on the manuscript. Special thanks go to the IT support staff at the Wellcome Trust Center for Neuroimaging and Virgina Tech Carilion Research Institute.