Cognitive load and mixed strategies: On brains and minimax

It is well-known that laboratory subjects often do not play mixed strategy equilibrium games according to the equilibrium predictions. In particular, subjects often mix with the incorrect proportions and their actions often exhibit serial correlation. However, little is known about the role of cognition in these observations. We conduct an experiment where subjects play a repeated hide and seek game against a computer opponent programmed to play either a strategy that can be exploited by the subject (a naive strategy) or designed to exploit suboptimal play of the subject (an exploitative strategy). The subjects play with either fewer available cognitive resources (under a high cognitive load) or with more available cognitive resources (under a low cognitive load). While we observe that subjects do not mix in the predicted proportions and their actions exhibit serial correlation, we do not find strong evidence these are related to their available cognitive resources. This suggests that the standard laboratory results on mixed strategies are not associated with the availability of cognitive resources. Surprisingly, we find evidence that subjects under a high load earn more than subjects under a low load. However, we also find that subjects under a low cognitive load exhibit a greater rate of increase in earnings across rounds than subjects under a high load.