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 manipulated 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 are available for deliberation on the choice. In our experiment, subjects played a finitely repeated multi-player prisoner's dilemma game under two cognitive load treatments. In one treatment, subjects were placed under a high cognitive load (given a 7 digit number to recall) and subjects in the other were placed under a low cognitive load (given a 2 digit number). According to two different measures, we find evidence that the low load subjects behaved more strategically. First, the low load subjects exhibited more strategic defection near the end of play 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.