When is a view unusual? A single case study of orientation-dependent visual agnosia

Several hypotheses have been proposed to explain why some neurological patients fail to recognise objects from unusual views: that it results from difficulty identifying an object's principal axis when it is foreshortened, identifying an object when landmark features are occluded, or an inability to rotate mental images. It was possible to test these hypotheses by examining the recognition abilities of a single case (A.S.), by using stimuli that were "unusual" only because of picture-plane misorientation. A.S. showed a recognition deficit in which his accuracy was proportional to the extent of misorientation from the normal upright for the object-although both principal axis and feature information remain visible after picture-plane rotation. Furthermore, A.S. performed with normal accuracy, and normal pattern of reaction time performance, on tasks of mental rotation. These findings suggest that none of these traditional accounts can adequately explain why this patient was unable to recognise objects from unusual views. These findings are discussed the light of recent suggestions of the basis of this type of disorder.

[1]  Elizabeth K. Warrington,et al.  Disorders of visual perception in patients with localised cerebral lesions , 1967 .

[2]  R. Shepard,et al.  Mental Rotation of Three-Dimensional Objects , 1971, Science.

[3]  P. Jolicoeur.  The time to name disoriented natural objects , 1985, Memory & cognition.

[4]  Martha J. Farah,et al.  The Neuropsychology of High-Level Vision , 1994 .

[5]  Pierre Jolicoeur,et al.  Identification of Disoriented Objects: A Dual‐systems Theory , 1990 .

[6]  E. Warrington,et al.  Two Categorical Stages of Object Recognition , 1978, Perception.

[7]  S. Pinker,et al.  Visual cognition : An introduction * , 1989 .

[8]  G. Humphreys,et al.  Routes to Object Constancy: Implications from Neurological Impairments of Object Constancy , 1984, The Quarterly journal of experimental psychology. A, Human experimental psychology.

[9]  David I. Perrett,et al.  Issues of representation in object vision , 1994 .

[10]  M. Farah,et al.  Mental rotation and orientation-invariant object recognition: Dissociable processes , 1988, Cognition.

[11]  J. G. Snodgrass,et al.  A standardized set of 260 pictures: norms for name agreement, image agreement, familiarity, and visual complexity. , 1980, Journal of experimental psychology. Human learning and memory.

[12]  Keith R. Laws,et al.  Object Recognition without Knowledge of Object Orientation , 1995, Cortex.

[13]  M. Tarr,et al.  Mental rotation and orientation-dependence in shape recognition , 1989, Cognitive Psychology.

[14]  E. Warrington,et al.  Visual Object Recognition in Patients with Right-Hemisphere Lesions: Axes or Features? , 1986, Perception.

[15]  Ernest Greene,et al.  The effect of stroke on object recognition , 1988, Brain and Cognition.

[16]  Glyn W. Humphreys,et al.  Normal and pathological processes in visual object constancy. , 1987 .

[17]  A. Taylor,et al.  The contribution of the right parietal lobe to object recognition. , 1973, Cortex; a journal devoted to the study of the nervous system and behavior.

[18]  E K Warrington,et al.  Selective impairment of topographical memory: a single case study. , 1978 .