Cognitive load in the multi-player prisoner's dilemma game: Are there brains in games?

We find that differences in the ability to devote cognitive resources to a strategic interaction imply differences in strategic behavior. In our experiment, we manipulate the availability of cognitive resources by applying a differential cognitive load. In cognitive load experiments, subjects are directed to perform a task which occupies cognitive resources, in addition to making a choice in another domain. The greater the cognitive resources required for the task implies that fewer such resources will be available for deliberation on the choice. Although much is known about how subjects make decisions under a cognitive load, little is known about how this affects behavior in strategic games. We run an experiment in which subjects play a repeated multi-player prisoner's dilemma game under two cognitive load treatments. In one treatment, subjects are placed under a high cognitive load (given a 7 digit number to recall) and subjects in the other are placed under a low cognitive load (given a 2 digit number). According to two different measures, we find evidence that the low load subjects behave more strategically. First, the behavior of the low load subjects converged to the Subgame Perfect Nash Equilibrium prediction at a faster rate than the high load subjects. Second, we find evidence that low load subjects were better able to condition their behavior on the outcomes of previous periods