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The role of Funktionswandel in metamorphopsia
Author(s) -
Nijboer Tanja C. W.,
Ruis Carla,
Worp H. Bart,
Haan Edward H. F.
Publication year - 2008
Publication title -
journal of neuropsychology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 37
eISSN - 1748-6653
pISSN - 1748-6645
DOI - 10.1348/174866407x256563
Subject(s) - metamorphopsia , psychology , perception , stimulus (psychology) , visual field , cognitive psychology , audiology , visual perception , sensory system , neuroscience , visual acuity , ophthalmology , medicine
Patients with metamorphopsia perceive objects or faces as being distorted and/or different in size. In most cases, recognition is not impaired. The stimulus specificity, particularly in the case of face perception, has led to the suggestion that metamorphopsia is a deficit at the entry level of category‐specific recognition systems; in this case, the face processing system. An explanation in terms of a visuosensory deficit (i.e. Funktionswandel ) that affects the perception of specific stimulus categories has not been systematically evaluated. In this study, we report two patients (MZ and CM) who experienced hemi‐metamorphopsia for faces after a stroke in the posterior part of the brain. Despite the distortions, they could still match and recognize faces. We carried out a detailed evaluation of their visual‐sensory status and found that both MZ and CM had specific problems with discriminating and estimating sizes and shapes, especially in the contralesional visual field. It was concluded that these cases, metamorphopsia was not due to a higher‐order perception impairment specific for faces, but rather of a specific impairment in shape perception in the contralesional visual field that proportionally affects the perception of faces.