Our research explores new implicit measures of cognitive responses to advertisements that focus on detecting the effects of specific thoughts. We first demonstrate that consumers' thoughts about persuasive messages can be assessed by both a thought recognition task and a belief verification task. We also show that performance on these tasks (i.e., jointly observed responses, reaction times, and confidence ratings) can be modeled as Poisson counting processes. Finally, we illustrate the effectiveness of these new measures in predicting consumers' product attitudes and that these measures can outperform traditional thought listing when people are unwilling or unable to report certain thoughts.