Dyslexia is different from reading difficulties resulting from other causes, such as a non-neurological deficiency with vision or hearing, or from poor or inadequate reading instruction. It is believed that dyslexia can affect between 5 and 10 percent of a given population although there have been no studies to indicate an accurate percentage (Vellutino, 1979).
There are three proposed cognitive subtypes of dyslexia (auditory, visual and attentional), although individual cases of dyslexia are better explained by specific underlying neuropsychological deficits and co-occurring learning disabilities (e.g. attention-deficit/hyperactivity disorder, math disability, etc.) Reading disability, or dyslexia, is the most common learning disability. Although it is considered to be a receptive language-based learning disability in the research literature, dyslexia also affects one 's expressive language skills. Adult dyslexics can read with good comprehension, but they tend to read more slowly than non-dyslexics and perform more poorly at spelling and nonsense word reading, a measure of phonological awareness. Dyslexia and IQ are not interrelated as a result of cognition developing on its own.
The World Federation of Neurology defines dyslexia as "a disorder manifested by difficulty in learning to read despite conventional instruction, adequate intelligence and sociocultural
References: 21 What Is Dyslexia? Education Research Foundation. Retrieved May, 2013 48 Henry, M K 16 Chung KK, Ho CS, Chan DW, Tsang SM, Lee SH (2010). Cognitive profiles of Chinese adolescents with dyslexia. Dyslexia 16 (1): 2–23 54 Nicolson RI, Fawcett AJ (2009).Dyslexia, dysgraphia, procedural learning and the cerebellum Bull L (2008). Survey of complementary and alternative therapies used by children with specific learning difficulties (dyslexia). Int J Lang Commun Disord 44 (2): 1. Connor, C.M.D.; Morrison, F.J.; Fishman, B.J.; Schatschneider, C.; Underwood, P Henry, M.K. (1998).Structured, sequential, multisensory teaching: the Orton legacy. Annals of Dyslexia 48: 3–26. 4 Wolf, Maryanne (2007) 16 speedchange.blogspot.com/2008/02/ghotit.html 18 Lyytinen, Heikki, Erskine, Jane, Aro, Mikko, Richardson, Ulla (2007) 21 Dahms, Joel. (2006). "Spelling Out Dyslexia". Northwest Science & Technology Hornickel, J., Zecker, S Vellutino, F. R. (1979). Dyslexia: Theory and research (pp. 74-81). Cambridge, MA: MIT press. Smythe, I., Everatt, J., & Salter, R Torgesen, J. K. (2004). Preventing early reading failure. American Educator, 28(3), 6-9.