Investigating form and colour perception in blindsight using an interference task.
Patients with striate cortical damage causing a hemianopic field defect can nevertheless demonstrate residual visual capacities in their blind field. Previous research investigating blindsight required patients to respond explicitly to stimuli appearing in the blind field by making forced choice judgements. We present data from a patient with a left occipital lesion resulting in a homonymous hemianopia, using the flanker task. This patient displayed a significant flanker congruency effect (FCE) for colour and letter stimuli even when they appeared in the blind field. A control patient with a lesion of the right thalamus showed no FCE in the blind field. This suggests that thalamo-extrastriate neural pathways are necessary for residual functioning in blindsight.
Danckert
J
J
School of Psychological Science, Faculty of Science and Technology, La Trobe University, Bundoora, Victoria, Australia.
Maruff
P
P
Kinsella
G
G
de Graaff
S
S
Currie
J
J
D000368:Aged; D000369:Aged, 80 and over; D002544:Cerebral Infarction / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000503:physiopathology; D002561:Cerebrovascular Disorders / Q000503:physiopathology; D003118:Color Perception / Q000502:physiology*; D005260:Female; D005556:Form Perception / Q000502:physiology*; D006423:Hemianopsia / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010775:Photic Stimulation; D011930:Reaction Time; D013788:Thalamus / Q000098:blood supply / Q000503:physiopathology; D014057:Tomography, X-Ray Computed; D014787:Vision Tests / Q000379:methods*; D014793:Visual Cortex / Q000098:blood supply / Q000503:physiopathology; D014795:Visual Pathways / Q000502:physiology