The study of Sumner et al.4 proposed unconscious inhibition in initiation of voluntary actions as a function of SMA-proper. In this study, subjects were presented a masked-prime stimulus followed by a visual target stimulus. Stimuli are arrows pointing to left or right with the same or opposite direction. The subjects were asked to press a left or right key according to target arrow direction. Subject reaction time (RT) was measured while there is a delay between masked- prime arrow and target arrow. If the delay was less than 100 milliseconds and the two arrows were the same, RT was decreased. In contrast, when the delay was more than 100 milliseconds, RT was increased even if prime and target were the same. Of course, this pattern was reported just for normal subjects and also patients with lateral premotor or pre-SMA lesions, but not for subjects with microlesions in SMA-proper.