c © 2008 The Review of Economic Studies Limited Stated Beliefs and Play in

Using data on one-shot games, we investigate whether players ’ actions can be viewed as responses to underlying expectations about their opponent’s behaviour. In our laboratory experiments, subjects play a set of 14 two-person 3 × 3 games and state beliefs about which actions they expect their opponents to play. The data sets from the two tasks are largely inconsistent. Rather, we find evidence that the subjects perceive the games differently when they (i) choose actions and (ii) state beliefs—their stated beliefs reveal deeper strategic thinking than their actions. On average, they fail to best respond to their own stated beliefs in almost half of the games. The inconsistency is confirmed by estimates of a unified statistical model that jointly uses the actions and the belief statements. There, we can control for decision noise and formulate a statistical test that rejects consistency. Effects of the belief elicitation procedure on subsequent actions are mostly insignificant. 1