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Front. Psychol. | doi: 10.3389/fpsyg.2018.02430

Task-Related Differences in Eye Movements in Individuals with Aphasia

 Kimberly G. Smith1*,  Joseph Schmidt2,  Bin Wang1, John M. Henderson3 and Julius Fridriksson4
  • 1Speech Pathology and Audiology, University of South Alabama, United States
  • 2Psychology, University of Central Florida, United States
  • 3University of California, Davis, United States
  • 4University of South Carolina, United States

Background: Neurotypical young adults show task-based modulation and stability of their eye movements across tasks. This study aimed to determine whether persons with aphasia (PWA) modulate their eye movements and show stability across tasks similarly to control participants.
Methods: Forty-eight PWA and age-matched control participants completed four eye-tracking tasks: scene search, scene memorization, text-reading, and pseudo-reading.
Results: Main effects of task emerged for mean fixation duration, saccade amplitude, and standard deviations of each, demonstrating task-based modulation of eye movements. Group by task interactions indicated that PWA produced shorter fixations relative to controls. This effect was most pronounced for scene memorization and for individuals who recently suffered a stroke. PWA produced longer fixations, shorter saccades, and less variable eye movements in reading tasks compared to controls. Three-way interactions of group, aphasia subtype, and task also emerged. Text-reading and scene memorization were particularly effective at distinguishing aphasia subtype. Persons with anomic aphasia showed a reduction in reading saccade amplitudes relative to their respective control group and other PWA. Persons with conduction/Wernicke’s aphasia produced shorter scene memorization fixations relative to controls or PWA of other subtypes, suggesting a memorization specific effect. Positive correlations across most tasks emerged for fixation duration and did not significantly differ between controls and PWA.

Conclusions: PWA generally produced shorter fixations and smaller saccades relative to controls particularly in scene memorization and text-reading respectively. The effect was most pronounced recently after a stroke. Selectively in reading tasks, PWA produced longer fixations and shorter saccades relative to controls, consistent with reading difficulty. PWA showed task-based modulation of eye movements, though the pattern of results was somewhat abnormal relative to controls. All subtypes of PWA also demonstrated task-based modulation of eye movements. However, persons with anomic aphasia showed reduced modulation of saccade amplitude and smaller reading saccades, possibly to improve reading comprehension. Controls and PWA generally produced stabile fixation durations across tasks and did not differ in their relationship across tasks. Overall, these results suggest there is potential to differentiate among PWA with varying subtypes and from controls using eye movement measures of task-based modulation, especially reading and scene memorization tasks.

Keywords: reading, scene viewing, Aphasia, modulation, Eye Movements

Received: 26 Apr 2018; Accepted: 19 Nov 2018.

Edited by:

Andrey R. Nikolaev, KU Leuven, Belgium

Reviewed by:

Jose P. Ossandon, Universität Hamburg, Germany
Esther S. Kim, University of Alberta, Canada  

Copyright: © 2018 Smith, Schmidt, Wang, Henderson and Fridriksson. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: PhD. Kimberly G. Smith, University of South Alabama, Speech Pathology and Audiology, Mobile, United States, kimberlysmith@southalabama.edu