Knowing where and knowing what: a double dissociation.
We report a double dissociation between visuo-spatial abilities and semantic knowledge (knowledge of the names and attributes of objects and people), in two brain-injured people with longstanding stable impairments, using a wide range of tests to explore the extent of the dissociation, MU, who has bilateral lesions of occipito-parietal cortex, shows severe spatial disorientation with relatively well-preserved semantic knowledge. He is contrasted with JBR, who has bilateral temporal lobe damage and shows severe semantic problems and no impairment on visuo-spatial tasks. Our findings thus demonstrate a double dissociation between the performance of semantic and spatial tasks by MU and JBR. This pattern is consistent with Ungerleider and Mishkin's (1982) neurophysiological hypothesis of separable cortical visual pathways; one which is specialised for spatial perception and follows a dorsal route from occipital to parietal lobes, and the other following a more ventral route from occipital to temporal lobes, whose target is semantic information needed in specifying what an object is.
Wilson
B A
BA
Medical Research Council Applied Psychology Unit, Cambridge, England.
Clare
L
L
Young
A W
AW
Hodges
J R
JR
D000328:Adult; D000701:Analgesics, Opioid / Q000506:poisoning; D001925:Brain Damage, Chronic / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology; D002540:Cerebral Cortex / Q000503:physiopathology; D003916:Dextromoramide / Q000506:poisoning; D004292:Dominance, Cerebral / Q000502:physiology; D062787:Drug Overdose / Q000175:diagnosis / Q000503:physiopathology / Q000523:psychology; D018792:Encephalitis, Viral / Q000175:diagnosis / Q000503:physiopathology / Q000523:psychology; D006561:Herpes Simplex / Q000175:diagnosis / Q000503:physiopathology / Q000523:psychology; D006801:Humans; D008297:Male; D011939:Mental Recall / Q000502:physiology*; D009483:Neuropsychological Tests; D009949:Orientation / Q000502:physiology*; D010364:Pattern Recognition, Visual / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology; D012660:Semantics; D013406:Suicide, Attempted / Q000523:psychology; D014706:Verbal Learning / Q000502:physiology*; D014795:Visual Pathways / Q000503:physiopathology
D000701:Analgesics, Opioid; D003916:Dextromoramide