The Perruchet effect refers to a dissociation between trends in the conscious expectancy of an event and trends in the strength or the speed of responding to that event, which suggests that learned changes in the performance of a response may be automatic. Despite being consistently demonstrated in conditioning studies and simple reaction time (RT) tasks, mixed results have been found in the choice variant of the Perruchet effect, especially when expectancy and responding are measured concurrently (that is, on the same trial). The present experiments examined why the dissociation disappears when concurrent measurement is used by directly comparing trials on which expectancy is measured to trials on which expectancy is not measured. In Experiment 1, expectancy was measured on a randomly chosen 50% of trials, whereas expectancy was measured every fourth trial in Experiment 2. In both experiments, the Perruchet effect was weakened on trials that immediately followed an expectancy rating but was still clearly evident on other trials, suggesting that automatic facilitation of RT based on recent trial history is temporarily masked, rather than abolished, by a concurrent expectancy judgment. (PsycINFO Database Record