An eye movement study on the role of the visual field defect in pure alexia

Pure alexia is a severe impairment of word reading which is usually accompanied by a right-sided visual field defect. Patients with pure alexia exhibit better preserved writing and a considerable word length effect, claimed to result from a serial letter processing strategy. Two experiments compared...

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Bibliographic Details
Published in:PloS one 2014-07, Vol.9 (7), p.e100898
Main Authors: Bormann, Tobias, Wolfer, Sascha A, Hachmann, Wibke, Lagrèze, Wolf A, Konieczny, Lars
Format: Article
Language:English
Subjects:
Aged
Alexia, Pure - diagnostic imaging
Alexia, Pure - physiopathology
Biology and Life Sciences
Defects
Dyslexia
Eye Movements
Fixation
Fixation, Ocular
Humans
Information processing
Linguistics
Medicine and Health Sciences
Middle Aged
Patients
Qualitative analysis
Reaction Time
Reading
Saccades
Social Sciences
Strategy
Tomography, X-Ray Computed
Visual field
Visual Fields
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Summary:Pure alexia is a severe impairment of word reading which is usually accompanied by a right-sided visual field defect. Patients with pure alexia exhibit better preserved writing and a considerable word length effect, claimed to result from a serial letter processing strategy. Two experiments compared the eye movements of four patients with pure alexia to controls with simulated visual field defects (sVFD) when reading single words. Besides differences in response times and differential effects of word length on word reading in both groups, fixation durations and the occurrence of a serial, letter-by-letter fixation strategy were investigated. The analyses revealed quantitative and qualitative differences between pure alexic patients and unimpaired individuals reading with sVFD. The patients with pure alexia read words slower and exhibited more fixations. The serial, letter-by-letter fixation strategy was observed only in the patients but not in the controls with sVFD. It is argued that the VFD does not cause pure alexic reading.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0100898