Bilateral Conflict: An Experimental Study of Strategic Effectiveness and Equilibrium

Bilateral conflict involves an attacker with several alternative attack methods and a defender who can take various actions to better respond to different types of attack. These situations have wide applicability to political, legal, and economic disputes, but they are particularly challenging to study empirically because the payoffs are unknown. Moreover, each party has an incentive to behave unpredictably, so theoretical predictions are stochastic. This article reports results of an experiment where the details of the environment are tightly controlled. The results sharply contradict the Nash equilibrium predictions about how the two parties’ choice frequencies change in response to the relative effectiveness of alternative attack strategies. In contrast, nonparametric quantal response equilibrium predictions match the observed treatment effects. Estimation of the experimentally controlled payoff parameters across treatments accurately recovers the true values of those parameters with the logit quantal response equilibrium model but not with the Nash equilibrium model.