Dyslexia is a reading disability that is not caused by an identifiable physical problem (such as brain damage, or visual or auditory issues).
Dyslexia is a specific learning disability characterized by a significant disparity between an individual's general intelligence and the person's language skills, usually reflected in school performance.
Estimates of people with dyslexia range from 5– 10% of the U.S. population, although some estimates place it as high as 17%. It is a complicated disorder with no identifiable cause or cure, yet it is highly responsive to treatment in the form of special instruction.
The most obvious symptoms of dyslexia are seen in an individual's reading and writing; however, listening, speaking, and general organizational skills are also affected. Individuals with dyslexia may have trouble transferring information across modalities, for example, from verbal to written forms. Characteristics include the following:
These characteristics were first thought to be the result of vision and perceptual problems (i.e., a failure of taking in the stimulus), but dyslexia is now typically described as primarily a language disorder. Whereas individuals typically acquire phonic (sound) rules intuitively while learning to read, individuals with dyslexia need specific, methodical drill and practice to learn the visual-auditory associations necessary for reading comprehension and written expression.
Dyslexia may be acquired or developmental. The former may result from a hearing problem caused by an early-childhood ear infection whereas the latter may arise from neurological or other congenital issues that increase susceptibility to the disability.
Originally it was thought that dyslexia affected many more males than females (in a ratio of 5:1), but later studies found it occurs nearly equally between males and females.
Specialized education is the typical treatment approach. American physician Samuel Torrey Orton (1879–1948) was the first researcher to identify and study dyslexia, and he developed the core principles of an educational approach in the 1920s. The work of three of his followers—teachers Bessie Stillman, Anna Gillingham, and Beth Slingerland—underlies many of the programs in wide use today. Such educational programs share the several features:
See also Learning disability .
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Eunice Kennedy Shriver National Institute of Child Health and Human Development, 31 Center Dr., Bldg. 31, Rm. 2A32, Bethesda, MD, 20892-2425, (800) 370-2943, NICHDInformationResourceCenter@mail.nih.gov, http://www.nichd.nih.gov .
International Dyslexia Association, 40 York Rd., 4th Fl., Baltimore, MD, 21204, (410) 296-0232, http://eida.org/contact.
Learning Disabilities Association of America, 4156 Library Rd., Pittsburgh, PA, 15234-1349, (412) 341-1515, info@LDAAmerica.org, http://ldaamerica.org .
National Center for Learning Disabilities, 32 Laight St., 2nd Fl., New York, NY, 10013, http://www.ncld.org/ .
National Institute of Mental Health, 6001 Executive Blvd., Rm. 6200, MSC 9663, Bethesda, MD, 20892-9663, (866) 615-6464, firstname.lastname@example.org, http://www.nimh.nih.gov .