The International Dyslexia Association adopted the following definition of dyslexia.  This definition is also used by the National Institute of Child Health and Human Development (NICHD).


Dyslexia is a specific learning disability that is neurobiological in origin.  It is characterized by difficulties with accurate and/or fluent word recognition and by poor spelling and decoding abilities. These difficulties typically result from a deficit in the phonological component of language that is often unexpected in relation to other cognitive abilities and the provision of effective classroom instruction. Secondary consequences may include problems in reading comprehension and reduced reading experience that can impede growth of vocabulary and background knowledge.


Dyslexia is a word of Greek origin.  “Dys” means problem, and “lexia” means language, so dyslexia simply means a problem with language. It falls under the larger umbrella of specific learning disabilities.   Dyslexia is a natural biological difference in the wiring of the brain that causes language to be processed differently (both written and oral) than in the general population.  Basically the brains of dyslexic people are not wired efficiently for language, so they have a difficult time learning to read, write, and spell.  However, their unique brain wiring may produce strengths in other areas, especially those that require creativity, innovation, and visual/spatial skills.


This video provides an excellent overview of dyslexia:


Dyslexia facts from the American Academy of Pediatrics (2011 article):

  • Depending on the criteria used, the prevalence of reading disability is approximately 5% to 20% of school-aged children in the United States.
  • 80% of people with learning disabilities have dyslexia.
  • Dyslexia has been identified as having a strong genetic basis.  Approximately 40% of siblings, children, or parents of an affected individual will have dyslexia.