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Grasping what is graspable: Evidence from visual form agnosia

McIntosh, R.D., Dijkerman, H.C., Mon-Williams, M. and Milner, A.D. (2004) Grasping what is graspable: Evidence from visual form agnosia. Cortex, 40 (4-5). pp. 695-702. ISSN 0010-9452

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Abstract

Patient DF has profound visual form agnosia. Despite this, she has no problem adjusting her finger-thumb grip aperture to the width of objects when reaching to grasp them. In a previous study, however, she was found to have great difficulty in scaling her grip aperture when attempting to grasp a transparent disc through two holes cut into it. This problem was attributed to a putative difference between the visual processing of size and distance in the brain, whereby DF retained the capacity for processing object size but not the separation between distinct elements such as holes. In the present study we have tested this idea more directly, and found no evidence to support such a distinction. Nonetheless, we replicated our earlier finding that DF is unable to produce normal prehension movements when attempting to grasp transparent stimuli by placing her digits into holes. We suggest that, whilst some simple objects offer themselves directly to the dorsal stream for grasping, an intact ventral stream is required to respond appropriately to more complex stimuli.

Item Type: Article
Keywords: agnosia; size; visuomotor; grasping; distance
Academic Units: The University of Leeds > Faculty of Medicine and Health (Leeds) > Institute of Psychological Sciences (Leeds) > Cognitive Psychology (Leeds)
Depositing User: Repository Officer
Date Deposited: 25 Jun 2009 09:06
Last Modified: 29 Sep 2010 14:24
Published Version: http://dx.doi.org/10.1016/S0010-9452(08)70165-5
Status: Published
Publisher: Elsevier Masson
Identification Number: 10.1016/S0010-9452(08)70165-5
URI: http://eprints.whiterose.ac.uk/id/eprint/8669

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