Evidence for perceptual deficits in associative visual (prosop)agnosia: a single-case study

Associative visual agnosia is classically defined as normal visual perception stripped of its meaning [Archiv für Psychiatrie und Nervenkrankheiten 21 (1890) 22/English translation: Cognitive Neuropsychol. 5 (1988) 155]: these patients cannot access to their stored visual memories to categorize the...

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Bibliographic Details
Published in:Neuropsychologia 2004, Vol.42 (5), p.597-612
Main Authors: Delvenne, Jean-François, Seron, Xavier, Coyette, Françoise, Rossion, Bruno
Format: Article
Language:English
Subjects:
Adult and adolescent clinical studies
Agnosia - complications
Biological and medical sciences
Brain - pathology
Brain Mapping
Case-Control Studies
Discrimination (Psychology) - physiology
Face recognition
Humans
Magnetic Resonance Imaging - methods
Male
Medical sciences
Memory Disorders - etiology
Mental Recall - physiology
Middle Aged
Neuropsychological Tests
Object recognition
Organic mental disorders. Neuropsychology
Prosopagnosia
Psychology. Psychoanalysis. Psychiatry
Psychomotor Performance - physiology
Psychopathology. Psychiatry
Reaction Time
Recognition (Psychology)
Visual associative agnosia
Visual Fields - physiology
Visual Perception
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Summary:Associative visual agnosia is classically defined as normal visual perception stripped of its meaning [Archiv für Psychiatrie und Nervenkrankheiten 21 (1890) 22/English translation: Cognitive Neuropsychol. 5 (1988) 155]: these patients cannot access to their stored visual memories to categorize the objects nonetheless perceived correctly. However, according to an influential theory of visual agnosia [Farah, Visual Agnosia: Disorders of Object Recognition and What They Tell Us about Normal Vision, MIT Press, Cambridge, MA, 1990], visual associative agnosics necessarily present perceptual deficits that are the cause of their impairment at object recognition Here we report a detailed investigation of a patient with bilateral occipito-temporal lesions strongly impaired at object and face recognition. NS presents normal drawing copy, and normal performance at object and face matching tasks as used in classical neuropsychological tests. However, when tested with several computer tasks using carefully controlled visual stimuli and taking both his accuracy rate and response times into account, NS was found to have abnormal performances at high-level visual processing of objects and faces. Albeit presenting a different pattern of deficits than previously described in integrative agnosic patients such as HJA and LH, his deficits were characterized by an inability to integrate individual parts into a whole percept, as suggested by his failure at processing structurally impossible three-dimensional (3D) objects, an absence of face inversion effects and an advantage at detecting and matching single parts. Taken together, these observations question the idea of separate visual representations for object/face perception and object/face knowledge derived from investigations of visual associative (prosop)agnosia, and they raise some methodological issues in the analysis of single-case studies of (prosop)agnosic patients.
ISSN:0028-3932
1873-3514
DOI:10.1016/j.neuropsychologia.2003.10.008