The dissociation between object identity and object orientation observed in six patients with brain damage, has been taken as evidence for a view-invariant model of object recognition. However, there was also some indication that these patients were not generally agnosic for object orientation but were able to gain access to at least some information about objects' canonical upright. We studied a new case (KB) with spared knowledge of object identity and impaired perception of object orientation using a forced choice paradigm to contrast directly the patient's ability to perceive objects' canonical upright vs non-upright orientations. We presented 2D-pictures of objects with unambiguous canonical upright orientations in four different orientations (0°, -90°, +90°, 180°). KB showed no impairment in identifying letters, objects, animals, or faces irrespective of their given orientation. Also, her knowledge of upright orientation of stimuli was perfectly preserved. In sharp contrast, KB was not able to judge the orientation when the stimuli were presented in a non-upright orientation. The findings give further support for a distributed view-based representation of objects in which neurons become tuned to the features present in certain views of an object. Since we see more upright than inverted animals and familiar objects, the statistics of these images leads to a larger number of neurons tuned for objects in an upright orientation. We suppose that probably for this reason KB's knowledge of upright orientation was found to be more robust against neuronal damage than knowledge of other orientations. Copyright (C) 2000 Elsevier Science Ltd.
Bibliographical noteFunding Information:
We are grateful to Oliver Turnbull and David Perrett for their helpful comments and thoughtful advice on a previous version of the manuscript. This work was supported by grants from the Deutsche Forschungsgemeinschaft awarded to the first author.
Copyright 2007 Elsevier B.V., All rights reserved.
- Brain damage
- Object orientation
- Object recognition
ASJC Scopus subject areas
- Experimental and Cognitive Psychology
- Cognitive Neuroscience
- Behavioral Neuroscience