Vision and visual attention of children with developmental dyslexia
Зрение и зрително внимание при деца с дислексия на развитието

Summary/Abstract: In the present research, we focus on deficits in the visual processing in children with developmental dyslexia (DD). The aim of the study was to examine the relationship between visual sensory dysfunction and visual-spatial attention in the context of DD and to reduce the visual stress by means of different colour filters. Four type examinations were applied: 1) a motion direction encoding, estimating of coherent motion thresholds; 2) detection of contrast thresholds of high-temporal and low-spatial frequency, low-temporal and high-spatial frequency gratings with doubling of their spatial frequency, embedded in external noise; 3) a visual-spatial attention task within a cue and an array of four coloured squares were used, one of which was located within a cue. For valid streams, the square inside the cue changed the colour. For invalid streams, one of the uncued squares changed the colour. The DD children had higher motion coherence thresholds for all types of coherence motion, higher contrast thresholds and difficulties detecting normal sinusoidal gratings than controls and they were also less sensitive to the frequency doubling (fd) illusion than normal readers. DD reader’s responses were less successful and slower than the controls for visual-spatial attention task. More dyslexics were influenced by the colour filters after 3 months training for the horizontal coherent task and high-temporal and low-spatial frequency doubling illusion task and less in low-temporal and high- spatial frequency doubling grating task. The reaction time was statistically significant when there were colour filters. There was evidence for visual-spatial attention deficits in relation to orienting and focusing in dyslexic readers.

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