Differences in reaction times and average evoked potentials as a function of direct and indirect neural pathways.

Average evoked potentials and manula response latencies were collected during a simple detection task in which brief visual stimuli were presented to the left and right visual fields. Latencies generated by the ipsilateral stimulus-hand combinations were shorter than contralateral combinations only under certain conditions, impugning the hypothesis that the reaction time difference reflects interhemispheric transfer time. Certain evoked potential components recorded contralateral to the stimulus occurred earlier than their ipsilateral counterparts, but whether this difference can be interpreted as representing interhemispheric transfer time is also questioned.