Activating response codes by stimuli in the neglected visual field.

The ability of 2 patients with a clinical deficit of extinction to process stimuli presented contralaterally to their lesions was tested with 2 variants of the flanker task. The patients saw 2 colored stimuli, 1 of which appeared in the center of the visual field and the other either on the ipsior contralateral side. In the peripheral report task, the patients had to report the color of the peripheral stimulus. In the center report task, the patients had to report the color of the central stimulus. The patients were much slower in the peripheral report task when the target was presented contralaterally to their lesion. By contrast, the responses in the center report task were equally influenced by ipsi- and contralateral flankers. The findings indicate that the patients were not impaired in the perceptual processing or the activation of response codes for contralateral stimuli. Their impairment is related to processes needed for generation of overt responses.