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Abstract:
Developmental dyslexia is often associated with deficits in
detecting auditory and visual stimuli, specifically those that
change over time. The aim of this study was to determine how
differences in sensory skills might relate to the component
phonological and orthographic skills necessary for reading
development. Thirty-nine adult subjects, 18 of whom had been
diagnosed as dyslexic, completed psychophysical tests of visual
coherent motion and global form detection, and acoustic frequency-
and amplitude-modulation (FM and AM) detection. Subjects also
completed assessments of literacy skill and component phonological
and orthographic sensitivity. For the psychophysical tasks, the
dyslexics were less sensitive than controls to coherent motion, 2
Hz FM and 20 Hz AM. No group differences were found for performance
on the coherent form, 240 Hz FM and 2 Hz AM detection measures.
Multiple regression analysis showed that dynamic visual and
auditory sensitivity predicted different aspects of reading skill.
Motion (but not form or auditory) sensitivity was a significant
predictor of orthographic skill, whereas thresholds for detecting 2
Hz FM and 20 Hz AM (but not motion) were independent predictors of
phonological skill. These findings highlight the separate
contributions of visual and auditory dynamic processing to variance
in component reading skills.
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