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

PLoS One. 2014 Jul 7;9(7):e100898. doi: 10.1371/journal.pone.0100898. eCollection 2014.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Alexia, Pure / diagnostic imaging
  • Alexia, Pure / physiopathology*
  • Eye Movements*
  • Fixation, Ocular
  • Humans
  • Linguistics
  • Middle Aged
  • Reaction Time
  • Saccades
  • Tomography, X-Ray Computed
  • Visual Fields*

Grant support

The article processing charge was funded by the open access publication fund of the Albert Ludwigs University Freiburg. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.