INVESTIGATING FORM AND COLOR-PERCEPTION IN BLINDSIGHT USING AN INTERFERENCE TASK

PATIENTS With striate cortical damage causing a hemianopic field defec t can nevertheless demonstrate residual visual capacities in their bli nd field. Previous research investigating blindsight required patients to respond explicitly to stimuli appearing in the blind field by maki ng forced choice judgements. We present data from a patient with a lef t occipital lesion resulting in a homonymous hemianopia, using the fla nker task. This patient displayed a significant flanker congruency eff ect (FCE) for colour and letter stimuli even when they appeared in the blind field. A control patient with a lesion of the right thalamus sh owed no FCE in the blind field. This suggests that thalamo-extrastriat e neural pathways are necessary for residual functioning in blindsight . NeuroReport 9: 2919-2925 (C) 1998 Lippincott Williams & Wilkins.