Inhibitory mechanisms involved in Stroop-matching and stop-signal tasks and the role of impulsivity.

Stroop-like and stop-signal tasks are commonly used to evaluate "inhibition", a multifaceted concept fundamental to better understanding of executive functions. Both tasks demand inhibitory processes for their execution; the first requires inhibition of an irrelevant attribute, while the second involves the inhibition of a prepotent motor response. Impulsivity and decision-making represent two other factors that could be associated to executive control and to inhibitory dyscontrol. In this study we developed a behavioral protocol combining the Stroop-matching (a variation of the classic Stroop task) and the stop-signal tasks to investigate possible interactions between the inhibitory mechanisms involved in both tasks. Moreover, we searched for associations between behavioral performance of healthy participants, and self-reported impulsivity and decision-making processes assessed by the BIS-11 scale and IGT, respectively. Our results showed that the primary-task reaction time in the Stroop-matching task influenced the ability to inhibit motor responses in the stop-signal task. Moreover, impulsiveness scores (but not decision-making) were associated to behavioral performance. Importantly, motor and attentional impulsiveness correlated differently to performance depending on the existence of stop-signal trials in the task. Our protocol revealed promising findings concerning the interaction between different inhibitory processes and their association with impulsivity levels.