Interhemispheric pathways in simple reaction time to lateralized light flash.

In two experiments, simple reaction time to left-field or right-field stimulation was measured as a function of light intensity. The response made on each trial in Experiment 1 was a finger movement, and in Experiment 2 a spoken word. In Experiment 1, the advantage of "uncrossed" over "crossed" reaction times remained invariant across intensities. In Experiment 2, however, the advantage of right over left visual-field stimuli in eliciting a vocal reaction varied inversely with intensity. It is suggested that the use of vocal reactions may permit an estimation of a visual commissural transmission time.