This paper investigates the relation between cognitive abilities and behavior in strategic-form games with the help of a novel experiment. The design allows us first to measure the cognitive abilities of sub-
jects without confound and then to evaluate their impact on behavior in strategic-from games. We find that subjects with better cognitive abilities show more sophisticated behavior and make better use of
information on cognitive abilities and preferences of opponents. Although we do not find evidence for Nash behavior, observed behavior is remarkably sophisticated, as almost 80% of subjects behave near
optimal and outperform Nash behavior with respect to expected pay-offs.