Influence of response modality on perceptual awareness of contralesional visual stimuli.

Visual extinction on double simultaneous stimulation was investigated in left and right brain-damaged patients in two response conditions: verbal and motor. In right brain-damaged patients contralesional detection was significantly worse when monitored by motor rather than by verbal responses in condition of single as well as of double stimulation. Previous research in normal subjects had shown that the left hemisphere is selectively involved in choice reactions such as those occurring in the motor condition of the present experiment in brain-damaged patients. The results of the latter are interpreted using as a basis the findings of that research and Kinsbourne's hemisphere activation hypothesis concerning unilateral neglect of space.