Nature 336, 766 - 767 (29 December 1988); doi:10.1038/336766a0

Blindsight and insight in visuo-spatial neglect

John C. Marshall & Peter W. Halligan^*

Neuropsychology Unit, University Department of Clinical Neurology, Oxford OX2 6HE, UK
^*Rivermead Rehabilitation Centre, Oxford OX1 4XD, UK

In a variety of neurological syndromes, patients may show tacit awareness of stimuli that cannot be consciously recollected or identified¹. Such dissociations are the defining characteristic of 'blindsight'^2,3; comparable phenomena are seen in some patients with amnesia⁴ and some with prosopagnosia, a profound impairment of familiar face recognition⁵. We report here an analogous dissociation between overt and covert perception in a case of visuo-spatial neglect⁶. The patient, P.S., had sustained right cerebral damage and failed overtly to process information in the hemispace contralateral to lesion. In common with most patients who manifest left-sided neglect, P.S. has a left homonymous hemianopia. Nonetheless, her neglect persists despite free movement of the head and eyes and is thus not a direct consequence of sensory loss in the left visual field. P.S. was presented simultaneously with two line drawings of a house, in one of which the left side was on fire. She judged that the drawings were identical; yet when asked to select which house she would prefer to live in, she reliably chose the house that was not burning.

References

1.	Schacter, D. L., McAndrews, M. P. & Moscovitch, M. in Thought Without Language (ed. Weiskrantz, L.) 242−278 (Clarendon, Oxford, 1988).
2.	Pöppel, E., Held, R. & Frost, D. Nature 243, 295−296 (1973). | Article | PubMed | ISI | ChemPort |
3.	Weiskrantz, L., Warrington, E. K., Sanders, M. D. & Marshall, J. Brain 97, 709−728 (1974). | PubMed | ISI | ChemPort |
4.	Milner, B., Corkin, S. & Teuber, H.-L. Neuropsychologia 6, 215−234 (1968). | Article | ISI |
5.	Bauer, R. M. Neuropsychologia 22, 457−469 (1984). | Article | PubMed | ISI | ChemPort |
6.	Jeannerod, M. (ed.) Neuropsychological and Neurophysiological Aspects of Spatial Neglect (North-Holland, Amsterdam, 1987).
7.	Kinsbourne, M. & Warrington, E. K. J. Neurol. Neurosur. Psychiat. 25, 339−344 (1962). | ChemPort |
8.	Weiskrantz, L. Brain 110, 77−92 (1987). | PubMed |
9.	de Haan, E. H. F., Young, A. W. & Newcombe, F. Cognitive Neuropsychol. 4, 385−415 (1987).
10.	Volpe, B. T., Ledoux, J. E. & Gazzaniga, M. S. Nature 282, 722−724 (1979). | PubMed | ChemPort |
11.	Karnath, H.-O. & Hartje, W. J. Neurol. 234, 180−184 (1987). | Article | PubMed | ChemPort |
12.	Fodor, J. A. The Modularity of Mind (MIT, Cambridge, Massachusetts, 1983).