I see this inability to 'tune out' extraneous stimuli from the environment in order to focus on a specific task or feature in children with many types of developmental disability. I talk about it in my book, where I call it 'wide spectrum tuning,' but I have never seen it in anyone with dyslexia. An interesting article apart from them going on about dyslexia having one cause! We already know of two!, - injury to part of the cerebellum and injury to parts of the 'magnocellular system.' Snowdrop provides therapy which helps to retune these attentional systems to more normal levels.
Dyslexia affects up to 17.5% of the population, but its cause remains somewhat unknown. A report published in the online journalPLoS ONEsupports the hypothesis that the symptoms of dyslexia, including difficulties in reading, are at least partly due to difficulty excluding excess background information like noise.
In the study of 37 undergraduate students, the researchers, led by Rachel Beattie of the University of Southern California, found that the poor readers performed significantly worse than the control group only when there were high levels of background noise.
The two groups performed comparably at the prescribed task when there was no background noise and when the stimulus set size was varied, either a large or a small set size.
According to Dr. Beattie, "these findings support a relatively new theory, namely that dyslexic individuals do not completely filter out irrelevant information when attending to letters and sounds. This external noise exclusion deficit could lead to the creation of inaccurate representations of words and phonemes and ultimately, to the characteristic reading and phonological awareness impairments observed in dyslexia."