Walsh & Hoyt: Varieties of Blindsight Phenomena

Given expectations that the spatial functions of the superior colliculus would be most likely to persist after cerebral lesions, the first demonstration of blindsight asked whether patients could direct saccades to target locations within hemianopic fields. There was a weak correlation of saccadic size and target position, mainly for a limited range of paracentral locations, as also noted in subsequent reports too. In some cases, localization occurred in regions that later recovered on perimetry. Also, several studies have failed to find saccadic localization in the absence of awareness. Targets in blind hemifields also have been localized by hand reaching and pointing. In some studies manual localization is weak and variable, sometimes only in patients with residual vision, but there are other reports of nearly normal manual localization. Motion. Form, color, and contrast. Interactions between blind and normal hemifields. Pupillary responses. Affective (fear) responses to unseen stimuli.