Characteristics of dyslexia
The characteristics of dyslexia have been identified mainly from research in languages with alphabetic writing systems, primarily English. However, many of these characteristic may be transferable to other types of writing systems.
Listening, speech and language
Some shared symptoms of the speech/hearing deficits and dyslexia:
- Confusion with before/after, right/left, and so on
- Difficulty learning the alphabet
- Difficulty with word retrieval or naming problems
- Difficulty identifying or generating rhyming words, or counting syllables in words (phonological awareness)
- Difficulty with hearing and manipulating sounds in words (phonemic awareness)
- Difficulty distinguishing different sounds in words (auditory discrimination)
- Difficulty in learning the sounds of letters
- Difficulty associating individual words with their correct meanings
- Difficulty with time keeping and concept of time
- Confusion with combinations of words
- Difficulty in organization skills
The identification of these factors results from the study of patterns across many clinical observations of dyslexic children. In the UK, Thomas Richard Miles was important in such work and his observations led him to develop the Bangor Dyslexia Diagnostic Test.
Dyslexia is about having problems with the visual notation of speech, which in most languages of European origin are problems with alphabet writing systems which have a phonetic construction. Experience of speech acquisition delays, and speech and language problems can be due to problems processing and decoding auditory input prior to reproducing their own version of speech, and may be observed as stuttering, cluttering or hesitant speech. There are a range of neurological issues in Speech and Language Pathology which can later cause problems accessing the visual notation of speech, dyslexic problems. Examples of these issues can be problems speaking in full sentences, problems correctly articulating Rs and Ls as well as Ms and Ns, mixing up sounds in multi-syllabic words (ex: aminal for animal, bisghetti for spaghetti, hekalopter for helicopter, hangaberg for hamburger, ageen for magazine, etc.), problems of immature speech "wed and gween" instead of "red and green". Some of these speech related problems can be caused by auditory processing disorder issues. Which can create a neurological auditory barrier to developing good phonological awareness skills, as a result some may develop alternative skills and which are based on recognising alphabetic words by their visual shape or Whole language and developing Logographic cues.
Reading and spelling
- Spelling errors — Because of difficulty learning letter-sound correspondences, individuals with dyslexia might tend to misspell words, or leave vowels out of words.
- Letter order - People with dyslexia may also reverse the order of two letters especially when the final, incorrect, word looks similar to the intended word (e.g., spelling "dose" instead of "does").
- Letter addition/subtraction - People with dyslexia may perceive a word with letters added, subtracted, or repeated. This can lead to confusion between two words containing most of the same letters.
- Highly phoneticized spelling - People with dyslexia also commonly spell words inconsistently, but in a highly phonetic form such as writing "shud" for "should". Dyslexic individuals also typically have difficulty distinguishing among homophones such as "their" and "there".
- Vocabulary - Having a small written vocabulary, even if they have a large spoken vocabulary.
Writing and motor skills
Because of literacy problems, an individual with dyslexia may have difficulty with handwriting. This can involve slower writing speed than average, poor handwriting characterised by irregularly formed letters, or inability to write straight on a blank paper with no guideline.
Some studies have also reported gross motor difficulties in dyslexia, including motor skills disorder. This difficulty is indicated by clumsiness and poor coordination. The relationship between motor skills and reading difficulties is poorly understood but could be linked to the role of the cerebellum and inner ear in the development of reading and motor abilities.
Dyslexia and dyscalculia are two learning disorders with different cognitive profiles. Dyslexia and dyscalculia have separable cognitive profiles, namely a phonological deficit in the case of dyslexia and a deficient number module in the case of dyscalculia.
Individuals with dyslexia can be gifted in mathematics while having poor reading skills. They might have difficulty with word processing problems (e.g. descriptive mathematics, engineering or physics problems that rely on written text rather than numbers or formulas).
A study has found that entrepreneurs are five times more likely to be dyslexic than average citizens.
Evidence based on randomly selected populations of children indicate that dyslexia affects boys and girls equally; that dyslexia is diagnosed more frequently in boys appears to be the result of sampling bias in school-identified sample populations.
In the United States, researchers estimate the prevalence of dyslexia to range from three to ten percent of school-aged children though some have put the figure as high as 17 percent. Recent studies indicate that dyslexia is particularly prevalent among small business owners, with roughly 20 to 35 percent of US and British entrepreneurs being affected.
- Miles, T.R. (1983). Dyslexia: the Pattern of Difficulties. Oxford: Blackwell. ISBN 0246113456.
- Stephen Wilcox - Dyslexia & Vision
- Brazeau-Ward, Louise (2001). DYSLEXIA AND THE UNIVERSITY. Canada: Canadian Dyslexia Centre (CDC) Inc.. pp. 6–13. ISBN 1-894964-71-3. http://www.dyslexiaassociation.ca/english/files/universityanddyslexia.pdf.
- Katz, Jack (2007-05-14). "APD Evaluation to Therapy: The Buffalo Model". AudiologyOnline. https://www.audiologyonline.com/articles/article_detail.asp?article_id=1803. Retrieved 2009-05-16.
- Nicolson, R. and Fawcett, A. (November 1999). "Developmental dyslexia: the role of the cerebellum". Dyslexia: an International Journal of Research and Practice 5: 155–7.
- Landerl, Karin; Barbara Fussenegger, Kristina Moll and Edith Willburger (2009-07-03). "Dyslexia and dyscalculia: Two learning disorders with different cognitive profiles". Journal of Experimental Child Psychology 103 (3): 309–324. doi:10.1016/j.jecp.2009.03.006. PMID 19398112. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WJ9-4W55T6D-1&_user=10&_coverDate=07%2F31%2F2009&_alid=922852997&_rdoc=7&_fmt=high&_orig=search&_cdi=6873&_sort=d&_docanchor=&view=c&_ct=4981&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=0cea87623399ba263468f47dd5266a28. Retrieved 2009-05-24.
- cass.city.ac.uk Entrepreneurs five times more likely to suffer from dyslexia
- Shaywitz, Sally E., M.D., and Bennett A. Shaywitz, M.D. (2001) The Neurobiology of Reading and Dyslexia. National Center for the Study of Adult Learning and Literacy Focus on Basics, Volume 5, Issue A - August 2001.
- Shaywitz, Sally E.; Bennett A. Shaywitz (August 2001). "The Neurobiology of Reading and Dyslexia". Focus on Basics (National Center for the Study of Adult Learning and Literacy) 5 (A). http://www.ncsall.net/?id=278.
- Learning Disabilities: Multidisciplinary Research Centers, NIH Guide, Volume 23, Number 37, October 21, 1994, Full Text HD-95-005 ("LDRC longitudinal, epidemiological studies show that RD (dyslexia) affect at least 10 million children, or approximately 1 child in 5.")
- Brent Bowers (2007-12-06). "Tracing Business Acumen to Dyslexia". New York Times. http://www.nytimes.com/2007/12/06/business/06dyslexia.html. Cites a study by Julie Logan, professor of entrepreneurship at Cass Business School in London, among other literature.