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

Article Article scientifique Article Development of a viewing strategy during adaptation to an artificial central scotoma eng 2004 author Varsori Michael Alexander 106008 author Perez Fornos Angelica 0000-0003-3911-8826 534827 author Safran Avinoam B. 25462 author Whatham Andréw Robert 525221 2691-2705 10.1016/j.visres.2004.05.027 15358064 0042-6989 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. Adaptation, Physiological Adult Humans Photic Stimulation/methods Reading Recognition (Psychology) Scotoma/physiopathology Visual Fields Dewey 616.8 61 Département des neurosciences cliniques 226 false 210 Neuroprothèses sensorielles pour la restitution de l'audition et l'équilibre 268 Vision research 44 23 0a7bb78a-b291-4ef0-9bf4-00dc4d8e8cd7 Article (Published version) Restricted 1-s2.0-S0042698904002743-main.pdf 591157 application/pdf restrictedAccess Faculté de médecine / Section de médecine clinique / Département des neurosciences cliniques

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Development of a viewing strategy during adaptation to an artificial central scotoma	Vision research			2004	671	0

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Varsori, Michael Alexander