Associative (prosop)agnosia without (apparent) perceptual deficits: a case-study.
In associative agnosia early perceptual processing of faces or objects are considered to be intact, while the ability to access stored semantic information about the individual face or object is impaired. Recent claims, however, have asserted that associative agnosia is also characterized by deficits at the perceptual level, which are too subtle to be detected by current neuropsychological tests. Thus, the impaired identification of famous faces or common objects in associative agnosia stems from difficulties in extracting the minute perceptual details required to identify a face or an object. In the present study, we report the case of a patient DBO with a left occipital infarct, who shows impaired object and famous face recognition. Despite his disability, he exhibits a face inversion effect, and is able to select a famous face from among non-famous distractors. In addition, his performance is normal in an immediate and delayed recognition memory for faces, whose external features were deleted. His deficits in face recognition are apparent only when he is required to name a famous face, or select two faces from among a triad of famous figures based on their semantic relationships (a task which does not require access to names). The nature of his deficits in object perception and recognition are similar to his impairments in the face domain. This pattern of behavior supports the notion that apperceptive and associative agnosia reflect distinct and dissociated deficits, which result from damage to different stages of the face and object recognition process.
Anaki
David
D
Rotman Research Institute, Baycrest Centre for Geriatric Care, 3560 Bathurst St., Toronto, Ontario, Canada M6A 2E1.momos@psych.utoronto.ca
Kaufman
Yakir
Y
Freedman
Morris
M
Moscovitch
Morris
M
D000368:Aged; D000377:Agnosia / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D008297:Male; D011939:Mental Recall / Q000502:physiology*; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D009778:Occipital Lobe / Q000473:pathology; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010468:Perceptual Disorders / Q000503:physiopathology*; D011930:Reaction Time / Q000502:physiology