Visual perception in dyslexia is limited by sub-optimal scale selection

Abstract Readers with dyslexia are purported to have a selective visual impairment but the underlying nature of the deficit remains elusive. Here, we used a combination of behavioural psychophysics and biologically-motivated computational modeling to investigate if this deficit extends to object seg...

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Autores principales:	Richard Johnston, Nicola J. Pitchford, Neil W. Roach, Timothy Ledgeway
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2017
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/755e82e7b3844c9499e668b3f6e61411
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id	oai:doaj.org-article:755e82e7b3844c9499e668b3f6e61411
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spelling	oai:doaj.org-article:755e82e7b3844c9499e668b3f6e614112021-12-02T15:06:24ZVisual perception in dyslexia is limited by sub-optimal scale selection10.1038/s41598-017-06967-62045-2322https://doaj.org/article/755e82e7b3844c9499e668b3f6e614112017-07-01T00:00:00Zhttps://doi.org/10.1038/s41598-017-06967-6https://doaj.org/toc/2045-2322Abstract Readers with dyslexia are purported to have a selective visual impairment but the underlying nature of the deficit remains elusive. Here, we used a combination of behavioural psychophysics and biologically-motivated computational modeling to investigate if this deficit extends to object segmentation, a process implicated in visual word form recognition. Thirty-eight adults with a wide range of reading abilities were shown random-dot displays spatially divided into horizontal segments. Adjacent segments contained either local motion signals in opposing directions or analogous static form cues depicting orthogonal orientations. Participants had to discriminate these segmented patterns from stimuli containing identical motion or form cues that were spatially intermingled. Results showed participants were unable to perform the motion or form task reliably when segment size was smaller than a spatial resolution (acuity) limit that was independent of reading skill. Coherence thresholds decreased as segment size increased, but for the motion task the rate of improvement was shallower for readers with dyslexia and the segment size where performance became asymptotic was larger. This suggests that segmentation is impaired in readers with dyslexia but only on tasks containing motion information. We interpret these findings within a novel framework in which the mechanisms underlying scale selection are impaired in developmental dyslexia.Richard JohnstonNicola J. PitchfordNeil W. RoachTimothy LedgewayNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 7, Iss 1, Pp 1-11 (2017)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Richard Johnston Nicola J. Pitchford Neil W. Roach Timothy Ledgeway Visual perception in dyslexia is limited by sub-optimal scale selection
description	Abstract Readers with dyslexia are purported to have a selective visual impairment but the underlying nature of the deficit remains elusive. Here, we used a combination of behavioural psychophysics and biologically-motivated computational modeling to investigate if this deficit extends to object segmentation, a process implicated in visual word form recognition. Thirty-eight adults with a wide range of reading abilities were shown random-dot displays spatially divided into horizontal segments. Adjacent segments contained either local motion signals in opposing directions or analogous static form cues depicting orthogonal orientations. Participants had to discriminate these segmented patterns from stimuli containing identical motion or form cues that were spatially intermingled. Results showed participants were unable to perform the motion or form task reliably when segment size was smaller than a spatial resolution (acuity) limit that was independent of reading skill. Coherence thresholds decreased as segment size increased, but for the motion task the rate of improvement was shallower for readers with dyslexia and the segment size where performance became asymptotic was larger. This suggests that segmentation is impaired in readers with dyslexia but only on tasks containing motion information. We interpret these findings within a novel framework in which the mechanisms underlying scale selection are impaired in developmental dyslexia.
format	article
author	Richard Johnston Nicola J. Pitchford Neil W. Roach Timothy Ledgeway
author_facet	Richard Johnston Nicola J. Pitchford Neil W. Roach Timothy Ledgeway
author_sort	Richard Johnston
title	Visual perception in dyslexia is limited by sub-optimal scale selection
title_short	Visual perception in dyslexia is limited by sub-optimal scale selection
title_full	Visual perception in dyslexia is limited by sub-optimal scale selection
title_fullStr	Visual perception in dyslexia is limited by sub-optimal scale selection
title_full_unstemmed	Visual perception in dyslexia is limited by sub-optimal scale selection
title_sort	visual perception in dyslexia is limited by sub-optimal scale selection
publisher	Nature Portfolio
publishDate	2017
url	https://doaj.org/article/755e82e7b3844c9499e668b3f6e61411
work_keys_str_mv	AT richardjohnston visualperceptionindyslexiaislimitedbysuboptimalscaleselection AT nicolajpitchford visualperceptionindyslexiaislimitedbysuboptimalscaleselection AT neilwroach visualperceptionindyslexiaislimitedbysuboptimalscaleselection AT timothyledgeway visualperceptionindyslexiaislimitedbysuboptimalscaleselection
_version_	1718388455448248320

Visual perception in dyslexia is limited by sub-optimal scale selection

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