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2D but not 3D: pictorial-depth deficits in a case of visual agnosia

2D but not 3D: pictorial-depth deficits in a case of visual agnosia
2D but not 3D: pictorial-depth deficits in a case of visual agnosia
Patients with visual agnosia exhibit acquired impairments in visual object recognition, that may or may not involve deficits in low-level perceptual abilities. Here we report a case (patient DM) who after head injury presented with object recognition deficits. He still appears able to extract 2D information from the visual world in a relatively intact manner; but his ability to extract pictorial information about 3D object-structure is greatly compromised. His copying of line drawings is relatively good, and he is accurate and shows apparently normal mental rotation when matching or judging objects tilted in the picture-plane. But he performs poorly on a variety of tasks requiring 3D representations to be derived from 2D stimuli, including: performing mental rotation in depth, rather than in the picture-plane; judging the relative depth of two regions depicted in line-drawings of objects; and deciding whether a line-drawing represents an object that is ‘impossible’ in 3D. Interestingly, DM failed to show several visual illusions experienced by normals (Muller-Lyer and Ponzo), that some authors have attributed to pictorial depth cues. Taken together, these findings indicate a deficit in achieving 3D intepretations of objects from 2D pictorial cues, that may contribute to object-recognition problems in agnosia.
0010-9452
723-738
Turnbull, Oliver H.
240e2f77-8509-48da-8e9b-1d80419acd14
Driver, Jon
40d4e5ba-cae1-46dc-b41c-2badd22fb2bd
McCarthy, Rosaleen A.
5377d3de-2597-4427-801b-6b4c61058568
Turnbull, Oliver H.
240e2f77-8509-48da-8e9b-1d80419acd14
Driver, Jon
40d4e5ba-cae1-46dc-b41c-2badd22fb2bd
McCarthy, Rosaleen A.
5377d3de-2597-4427-801b-6b4c61058568

Turnbull, Oliver H., Driver, Jon and McCarthy, Rosaleen A. (2004) 2D but not 3D: pictorial-depth deficits in a case of visual agnosia. Cortex, 40 (4/5), 723-738.

Record type: Article

Abstract

Patients with visual agnosia exhibit acquired impairments in visual object recognition, that may or may not involve deficits in low-level perceptual abilities. Here we report a case (patient DM) who after head injury presented with object recognition deficits. He still appears able to extract 2D information from the visual world in a relatively intact manner; but his ability to extract pictorial information about 3D object-structure is greatly compromised. His copying of line drawings is relatively good, and he is accurate and shows apparently normal mental rotation when matching or judging objects tilted in the picture-plane. But he performs poorly on a variety of tasks requiring 3D representations to be derived from 2D stimuli, including: performing mental rotation in depth, rather than in the picture-plane; judging the relative depth of two regions depicted in line-drawings of objects; and deciding whether a line-drawing represents an object that is ‘impossible’ in 3D. Interestingly, DM failed to show several visual illusions experienced by normals (Muller-Lyer and Ponzo), that some authors have attributed to pictorial depth cues. Taken together, these findings indicate a deficit in achieving 3D intepretations of objects from 2D pictorial cues, that may contribute to object-recognition problems in agnosia.

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More information

Published date: 2004
Additional Information: In special section on de Renzi (1982). Disorders of space exploration and cognition: two decades later. Guest editor: David P. Carey

Identifiers

Local EPrints ID: 44874
URI: http://eprints.soton.ac.uk/id/eprint/44874
ISSN: 0010-9452
PURE UUID: daf4d87a-730c-41b1-b7b6-c631bd757632

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Date deposited: 20 Mar 2007
Last modified: 15 Mar 2024 09:08

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Contributors

Author: Oliver H. Turnbull
Author: Jon Driver
Author: Rosaleen A. McCarthy

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