Scientific article
English

Development of a viewing strategy during adaptation to an artificial central scotoma

Published inVision research, vol. 44, no. 23, p. 2691-2705
Publication date2004
Abstract

Although many individuals with a central scotoma develop eccentric fixation most often beneath or left of the scotoma, little is known about how they come to develop a particular viewing strategy. We investigated this by asking eight subjects with normal vision to read isolated letters, words and text passages while an artificial scotoma covered a central portion of the visual field. We quantified viewing strategy and analysed changes in their viewing behaviour over 8-10 sessions within a two-week period. Subjects read while either a horizontal (n=4) or vertical bar scotoma (n=4), 10 degrees wide, covered the entire horizontal or vertical meridian of the stimulus field. For the horizontal scotoma group: (1) there was an increasing preference to use the inferior visual field for isolated letters/words and text passages, which was essentially complete within the test period; (2) the superior visual field was preferred when reading letters/words initially presented in upper visual space and the inferior visual field when reading letters/words initially presented in lower visual space; (3) in general, variation in viewing strategy according to stimulus position diminished over the sessions for all stimuli. For the vertical scotoma group: (1) two subjects used the left and right visual fields in approximately equal proportion to view isolated letters/words, one subject showed a weak preference to use the left visual field and one subject developed a strong preference for using the right visual field; (2) the text passages could be read with combined use of left and right visual fields in a specific manner; (3) the left visual field was preferred to view stimuli initially presented in left visual space while the right visual field was preferred for words initially presented in right visual space. This effect diminished across sessions. Overall, these findings indicate that (1) a specific viewing strategy can be developed through as little as 5 hours of reading experience without guided training; (2) two distinctly separate retinal areas can be used in an integrated manner during reading; (4) stimulus position in visual space can influence viewing strategy; (5) in general, reading encourages a preference for the inferior over the superior visual field, but not the left over right visual field. Letter/word/text recognition and reading speeds increased progressively across sessions, even after scotoma lateralisation appeared stabilised suggesting that multiple mechanism are involved in adaptive changes.

Keywords
  • Adaptation, Physiological
  • Adult
  • Humans
  • Photic Stimulation/methods
  • Reading
  • Recognition (Psychology)
  • Scotoma/physiopathology
  • Visual Fields
Citation (ISO format)
VARSORI, Michael Alexander et al. Development of a viewing strategy during adaptation to an artificial central scotoma. In: Vision research, 2004, vol. 44, n° 23, p. 2691–2705. doi: 10.1016/j.visres.2004.05.027
Main files (1)
Article (Published version)
accessLevelRestricted
Identifiers
Journal ISSN0042-6989
670views
0downloads

Technical informations

Creation02/06/2014 10:30:00
First validation02/06/2014 10:30:00
Update14/03/2023 21:22:17
Status update14/03/2023 21:22:17
Last indexation30/10/2024 19:06:22
All rights reserved by Archive ouverte UNIGE and the University of GenevaunigeBlack