What is dyslexia?
Dyslexia is a neurologically-based condition that affects word-level reading accuracy, reading fluency, and spelling. It is often described as an unexpected difficulty in learning to read.
The formal definition of dyslexia by the International Dyslexia Association is:
“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 varies in severity and the impact depends on the effectiveness of reading instruction and/or remediation.
What are the signs of dyslexia?
Click here for a list of common signs of dyslexia at different ages.
Some individuals with dyslexia learn early reading and spelling tasks, especially with excellent instruction. But later they may have serious difficulties when more complex language skills are required to read and write more difficult text.
What causes dyslexia?
Brain imagery studies have shown that dyslexia is neurologically based. These studies have shown that people with dyslexia have not developed the neural network in the brain that is typical of successful readers.
A key problem for many people with dyslexia is difficulty with identifying the separate speech sounds within a word and/or learning how letters represent those sounds. Other people have difficulty in rapidly identifying letters and words, making it very difficult to read fluently.
Check out this interesting interview with Guinevere Eden, a neuroscientist, talking about reading and the brain.
Is dyslexia related to intelligence or motivation?
Dyslexia is NOT related to intelligence or lack of desire to learn.
Is dyslexia a common learning disability?
Dyslexia is the most common type of learning disability.
Reading ability is on a continuum so estimates of the prevalence of dyslexia depend on what criteria are used. However, it is estimated that between 5-20% of the population struggle to read due to dyslexia.
Is dyslexia hereditary?
Dyslexia runs in families. Parents with dyslexia are very likely to have children with dyslexia.
Is dyslexia the same as 'specific learning disorder'?
In psycho-educational assessments, psychologists often use the term ‘specific learning disorder‘ or ‘specific learning disorder with impairment in reading’ which is characterized as “one where people have difficulties with word reading accuracy, reading rate or fluency and reading comprehension” (The Diagnostic and Statistical Manual of Mental Disorders (DSM-V), 5th Edition ,2013, The American Psychiatric Association).
The DSM-V stipulates that “dyslexia is an alternative term used to refer to a pattern of learning difficulties characterized by problems with accurate or fluent word recognition, poor decoding, and poor spelling abilities".
Hence, dyslexia is an equivalent term for the same condition of difficulty with word-level reading and spelling.
See the page on Formal assessment of dyslexia for more information about equivalent terms.
What are the emotional consequences of dyslexia?
Dyslexia can seriously affect a person’s confidence and self-image. Students with dyslexia often feel “dumb”, embarrassed, and less capable academically than they actually are. Students with dyslexia may become very discouraged with school and are at risk of developing mental health issues such as anxiety and depression.
Can dyslexia be 'cured'?
Dyslexia is a life-long condition that people don’t ‘out-grow’. However, effective 'structured literacy' instruction can help people with dyslexia learn to read accurately and fluently. Research studies have shown that structured literacy intervention results in the development of a neural network in the brain that is more typical of successful readers. As well, supporting your child at home and at school will help your child build on their strengths and be successful in life.
Why do some readers confuse 'b' and 'd', 'p' and 'q'?
Stanislas Dehaene, in his book Reading in the Brain, explains why many young readers confuse the letters b and d, or p and q. Note that these letters are mirror images of each other (flip them and they are the same) - they are ‘symmetrical views’. Our brains are wired to recognize objects regardless of the orientation - we immediately recognize a chair as a chair whether it is facing right or left. Dehaene explains that as children learn to read and write, usually it takes several months to learn to distinguish mirror letters (‘b’ and ‘d'); they have to learn that these are not the same objects. The problem may be confounded in children with dyslexia who have phonological awareness difficulties; they may find it difficult to distinguish the /b/ and /d/ phonemes (sounds) .. they are quite similar, voiced sounds, both produced at the front of the mouth. Similarly, /p/ and /q/ phonemes (sounds) are both unvoiced and can be difficult to distinguish for some students with dyslexia.
Confusion of b, d, p and q can persist in some students, and more work is required for them to overcome the wired perception that they are the same object. There is evidence that instruction in handwriting and activities that emphasize motor gestures can be helpful in overcoming this confusion. Instruction should emphasize the order and how the letter strokes are drawn (e.g. moving top to bottom, left to right).
Do visual therapies help students with dyslexia?
Many myths persist regarding dyslexia and vision. In 2011 the American Academy of Pediatrics, along with a number of other organizations (American Academy of Ophthalmology, Am Ass for Pediatric Ophthalmology and Strabismus, and the American Association of Certified Orthoptists), published a Joint Technical Report on Learning Disabilities, Dyslexia, and Vision (Handler & Fierson, 2011). This was reaffirmed by the American Academy of Ophthalmology in 2014 and revisited by Handler & Fierson in 2017. The Technical Report states:
No consistent relationship between visual function and academic performance and reading ability has been shown.... Currently, there is inadequate scientific evidence to support that view that subtle eye or visual problems, including abnormal focusing, jerky eye movements, misaligned or crossed eyes, visual-motor dysfunction, binocular dysfunction, perceptual dysfunctions, or hypothetical difficulties with laterality or ‘trouble crossing the middle’ of the visual field, cause or increase the severity of learning disabilities”.
Handler and Fierson (2017) explain:
“Vision problems may coexist with dyslexia but are not more prevalent than in the general population… children with reading impairment have the same visual function as children without reading impairment (Creaven et al 2015). Although visual problems, including convergence insufficiency, can hamper reading, they are not the cause of reading disability”.
There are many therapies, treatments, and products on the market that claim to improve reading through addressing "visual" deficits. The Technical Report states:
"Scientific evidence does not support the claims that visual training, muscle exercises, ocular pursuit-and-tracking exercises, behavioral/perceptual vision therapy, “training” glasses, prisms, and colored lenses and filters are effective direct or indirect treatments for learning disabilities… Vision therapy does not treat learning disabilities or dyslexia.”
Handler & Fierson (2017) also express the concern that
“..the use of visual therapy and training glasses may give parents and teachers the false sense that a child’s reading difficulties are being adequately addressed, delaying critical remedial treatment that is most effective when started before the student reaches grade 3.”
Vision problems do not cause dyslexia and the visual therapies listed above do not ‘cure’ dyslexia. However, some children with dyslexia may have a co-occurring treatable vision problem, so the Technical report recommends these children have a comprehensive pediatric medical eye examination by an ophthalmologist with experience in the assessment and treatment of children. Treatable ocular conditions can include strabismus, amblyopia, convergence and/or focusing deficiencies, and refractive errors (Am Acad Ophthalmology 2014). Further details of such an assessment are provided in the Technical report (Handler & Fierson, 2011) and the reports by the American Academy of Ophthalmology (2014), and Handler & Fierson, 2017.
References and more information:
American Academy of Ophthalmology. 2014. Joint statement: Learning disabilities, dyslexia, and vision - reaffirmed 2014.
Cowen, C.D. 2018. How to counter vision-based claims about dyslexia ‘cures’. International Dyslexia Association website.
Fletcher, J.M & D. Currie. 2011. Vision efficiency interventions and reading disability. Perspectives on Language and Literacy. Winter 2011: 21-24.
Handler, SM, Fierson WM, Section on Ophthalmology and Council for Children with Disabilities for the American Ass of Pediatrics, Amer Acad of Ophthalmology, Am Assoc of Pediatric Ophthalmology and Strabismus, Am Ass of Certified Orthoptists. 2011. Joint Technical Report - Learning disabilities, dyslexia, and vision. Pediatrics. 127:c818-56.
Handler S.M. & Fierson W.M. 2017. Reading difficulties and the pediatric ophthalmologist. Journal of American Association for Pediatric Ophthalmology and Strabismus. 21(6):436-442.
Southport CoLab and Florida Center for Reading Research. 2019. Do vision problems cause dyslexia? Infographic.
Are there any associated learning issues?
Some people with dyslexia have other issues that can affect their learning (eg. attention, memory) and hence, academic success. These must be considered when providing intervention programs and supporting children with dyslexia. Here are some examples:
Other learning disabilities
- Dysgraphia involves difficulties with handwriting. See IDA's Fact Sheet: Understanding Dysgraphia
- Dyscalculia involves difficulties with mathematics. See Understanding Dyscalculia by Understood.org
Attention and memory issues
- ADHD (Attention Deficit and Hyperactivity Disorder) affects attention, impulsiveness and/or hyperactivity. Approximately 30% of people with dyslexia also have ADHD.
- Working memory is memory used for temporarily storing and managing information. Poor working memory can make it difficult to retain letter/sounds while trying to decode an unfamiliar word or to remember the words in a long, complicated sentence.
- Executive function skills enable us to carry out instructions in a logical way and organize our thoughts and actions. Challenges in these skills can add to the difficulties experienced by someone with dyslexia.