Does covert inhibition potentiate online inhibitory control?

A planned action awaiting execution requires withholding a prepared response. We asked whether such a form of inhibitory control would interact with online decision processes that change a planned response. To study this issue with respect to oculomotor control, subjects performed visually (VG) guided, memory guided (MG) and delayed visually guided (DVG) saccades. In contrast to the VG task, subjects had to withhold a prepared response during the MG and the DVG task. In all three tasks, on a random fraction of trials a second target was presented after a variable delay, which instructed subjects to redirect their gaze to the newly specified target. The time taken to cancel a saccade, the target switch reaction time (TSRT) was calculated using a race model. We observed that although the reaction times were same for all the three tasks, the average TSRT was found to be significantly smaller for MG and the DVG compared to the VG task. Since, both MG and DVG require withholding a prepared saccade, a lower TSRT indicates that a tonic level of inhibition interacts with online decision processes to potentiate inhibitory control