Cognitive functions are impaired by moderate increasing BACs that do not affect motor movement, and the tactile sensory system may be relatively insensitive to this impairment.

Two experiments tested the adequacy of behavioral criteria to fractionate reaction time (RT) into independent premotor (cognitive) and motor components. Healthy participants performed an omitted stimulus reaction time task in which they responded to the termination of a train of lateralized visual, auditory or tactile stimuli. Exp. 1 with 48 participants (24 men) showed premotor RT was independent of motor RT in each sensory modality and did not differ as a function of side of presentation or sex. Repeated tests administered in Exp. 2 (N= 12) also showed no significant association between the behaviorally fractionated measures. These results are comparable to those obtained using muscle potential to fractionate RT and suggest behaviorally fractionated premotor and motor RT could be a reliable, useful tool in the assessment of cognitive and motor processing in different sensory modalities of healthy people or those with brain injury, disease, or drug-induced disturbances.