Adults with dyslexia exhibit large effects of crowding, increased dependence on cues, and detrimental effects of distractors in visual search tasks


Difficulties in visual attention are increasingly being linked to dyslexia. To date, the majority of studies have inferred functionality of attention from response times to stimuli presented for an indefinite duration. However, in paradigms that use reaction times to investigate the ability to orient attention, a delayed reaction time could also indicate difficulties in signal enhancement or noise exclusion once oriented. Thus, in order to investigate attention modulation and visual crowding effects in dyslexia, this study measured stimulus discrimination accuracy to rapidly presented displays. Adults with dyslexia (AwD) and controls discriminated the orientation of a target in an array of different numbers of - and differently spaced - vertically orientated distractors. Results showed that AwD: were disproportionately impacted by (i) close spacing and (ii) increased numbers of stimuli, (iii) did use pre-cues to modulate attention, but (iv) used cues less successfully to counter effects of increasing numbers of distractors. A greater dependence on pre-cues, larger effects of crowding and the impact of increased numbers of distractors all correlated significantly with measures of literacy. These findings extend previous studies of visual crowding of letters in dyslexia to non-complex stimuli. Overall, AwD do not use cues less, but they do use cues less successfully. We conclude that visual attention is an important factor to consider in the aetiology of dyslexia. The results challenge existing theoretical accounts of visual attention deficits, which alone are unable to comprehensively explain the pattern of findings demonstrated here.

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Divisions: College of Health & Life Sciences > School of Psychology
College of Health & Life Sciences > Clinical and Systems Neuroscience
College of Health & Life Sciences
College of Health & Life Sciences > Aston Institute of Health & Neurodevelopment (AIHN)
College of Health & Life Sciences > School of Optometry > Vision, Hearing and Language
Additional Information: NOTICE: this is the author’s version of a work that was accepted for publication in Neuropsychologia. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Moores, Elisabeth J.; Cassim, Rizan and Talcott, Joel B. (2011). Adults with dyslexia exhibit large effects of crowding, increased dependence on cues, and detrimental effects of distractors in visual search tasks. Neuropsychologia, 49 (14), pp. 3881-3890. DOI: 10.1016/j.neuropsychologia.2011.10.005.
Uncontrolled Keywords: developmental dyslexia,attention,crowding,orientation,noise,visualsearch
Publication ISSN: 1873-3514
Last Modified: 15 May 2024 07:09
Date Deposited: 09 Jan 2012 14:40
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Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
PURE Output Type: Article
Published Date: 2011-12
Authors: Moores, Elisabeth (ORCID Profile 0000-0003-3997-0832)
Cassim, Rizan
Talcott, Joel B. (ORCID Profile 0000-0001-7958-8369)


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