Neural mechanisms, temporal dynamics, and individual differences in interference control

Functional magnetic resonance imaging (fMRI) methods may help in understanding processes of response capture and response inhibition in conflict tasks, such as the Simon task. However, data-driven approaches thus far have not yielded consistent insights into these processes. Here, a theory-driven approach is introduced that capitalizes on individual differences in the processes of central interest. Based on the so-called activation-suppression model, specific behavioral parameters for each individual derived from reaction time (RT) distribution analysis were computed and entered into model-based fMRI analyses. These parameters correspond closely to the processes of inappropriate location-driven response activation (capture) and the subsequent inhibition of this activation as detailed by the model. Data from 24 participants revealed activation in the pre-supplementary motor area, which covaried with the RT distribution measure of response capture. Activation in the right inferior frontal cortex was found to covary with the RT distribution measure of response inhibition. These results, which are consistent against the backdrop of the larger literature on cognitive control, could have been derived neither from the standard data-driven fMRI approach, nor from inspecting overall mean RT alone.