COMMITMENT AND SELF‐CONTROL IN A PRISONER'S DILEMMA GAME

Abstract

Humans often make seemingly irrational choices in situations of conflict between a particular smaller—sooner reinforcer and a more abstract, temporally extended, but larger reinforcer. In two experiments, the extent to which the availability of commitment responses—self‐imposed restrictions on future choices—might improve self‐control in such situations was investigated. Participants played a prisoner's dilemma game against a computer that played a tit‐for‐tat strategy—cooperating after a participant cooperated, defecting after a participant defected. Defecting produced a small—immediate reinforcer (consisting of points convertible to gift cards) whereas cooperating increased the amount of subsequent reinforcers, yielding a greater overall reinforcer rate. Participants were normally free to cooperate or defect on each trial. Additionally, they could choose to make a commitment response that forced their choice for the ensuing five trials. For some participants, the commitment response forced cooperation; for others, it forced defection. Most participants, with either commitment response available, chose to commit repeatedly despite a minor point loss for doing so. After extended exposure to these contingencies, the commit‐to‐cooperate group cooperated significantly more than a control group (with no commitment available). The commit‐to‐defect group cooperated significantly less than the control group. When both commitment alternatives were simultaneously available—one for cooperation and one for defection—cooperation commitment was strongly preferred. In Experiment 2, the commitment alternative was removed at the end of the session; gains in cooperation, relative to the control group, were not sustained in the absence of the self‐imposed behavioral scaffold.