Trial structure of the stop signal and Stroop task.

<p>Example of a trial sequence in stop signal task (b) that parallels that in the Stroop task (a). In the Stroop task, color words that are printed in a color different from what the word says represent incongruent (I) trials; otherwise, they are congruent (C) trials. In the stop signal task, both stop success (SS) and stop error (SE) trials are incongruent trials, and involved in conflict processing, as compared to go (G) trials, which are congruent trials. In both tasks, trials are distinguished by their preceding trials. Thus, an incongruent trial following a congruent trial is “cI” in the Stroop task, and a SS trial following a go trial is “pG-SS” in the stop signal task.