Background: Dyslexia, also referred to as specific reading disability, is a condition where an individual demonstrates a level of reading that is significantly below what may be expected for his age or intelligence. Although the phonological deficit theory of dyslexia is widely accepted, there is accumulating evidence suggesting that at least a subset of dyslexic subjects demonstrate distinct visual attentional deficits. However, it is unclear if the magnitude of visual attention at attended and unattended locations is equivalent in poor and normal readers. The aim of the present study was to examine differences in the magnitude of attentional facilitation (benefits) and inhibition (costs) in response to an abrupt onset spatial cue in children with reading disabilities in comparison to controls.
Methods: A group of impaired readers (n=15), ages nine to 12 years, reading at a level at least 1.5 years below grade level and with average mathematics scores, were included in this study. The control group included an age-matched sample of normal readers (n=20). An adaptation of the covert orienting paradigm was used to investigate differences in magnitude of visual spatial attention between groups.
Results: Poor readers demonstrated smaller costs (t=2.07, p<0.02) at unattended locations in comparison to their normal counterparts. Additionally, poor readers were significantly slower (F(1,32) = 14.17, p<0.001) in moving spatial attention in response to an abrupt onset peripheral cue when compared to controls.
Conclusion: The poor readers in the current study were slower in shifting spatial attention in comparison to their normal counterparts. They also demonstrated smaller costs at unattended locations, providing indirect evidence for a diffuse attentional field in this group. Consistent with many studies in the literature, we have presented evidence for spatial attentional deficits in impaired readers, the implications of which are discussed within the context of some of the current models of attention.
Keywords: costs and benefits, dyslexia, spatial attention, specific reading disability