The minority game unpacked:

Abstract

We conduct an experiment on a minority-of-three game in which each player is a team composed of three subjects. Each team can freely discuss its strategies in the game and decisions must be made via majority rule. Team discussions are recorded and their content analyzed to detect evidence of strategy co-evolution among teams playing together. Our main results show no evidence supporting the mixed strategy Nash equilibrium solution, and provide evidence more consistent with reinforcement learning models than with belief-based models. Exhibiting level-2 rationality (i.e., reasoning about others’ beliefs) is positively and significantly correlated with higher than average earnings in the game. In addition, teams that are more successful tend to become more self-centered over time, paying more attention to their own past successes than to the behavior of other teams. Finally, we find evidence of mutual adaptation over time, as teams that are more strategic induce competing teams to be more self-centered instead. Our results contribute to the understanding of coordination dynamics resting on heterogeneity and co-evolution of decision rules. In addition, they provide support at the decision process level to the validity of modeling behavior using reinforcement learning models.