Dyslexia Comprehensive Guide: Overview

Table of contents:

Imagine not being able to read. Your qualifications would most likely exclude a 12th-grade certificate, seriously limiting your chances for academic and occupational success.

You could never apply for a job without assistance, being incapable of filling out an application form. You couldn’t read the instructions on medicine bottles and precautions on poisonous household chemicals, help your children with homework or treat them to bedtime stories, and you would be unable to correspond with family or friends. Choice, in all its facets, would be limited. Unable to read road signs and street names, you couldn’t travel freely. In a restaurant, you’d be forced to order from the few dish photos instead of the full menu. At the voting station you might vote for a face, a smile or a style, rather than a mind or character or body of beliefs. At the very least, you’d be severely challenged and isolated in a reading world.

Social, emotional, and economic impact

Poor reading skills cast a dark shadow. There is extensive evidence suggesting that learning to read is directly linked to a young child’s self-concept and mental well-being, and that children with hampered reading skills fare poorly academically. As the poor achiever’s hope for a fulfilling and productive life starts to diminish, they start to contribute significantly to the overall numbers of school dropouts, single parents, juvenile delinquents and imprisoned adults. As many as 75% of those incarcerated in the United States have not graduated from high school and 70% are functionally illiterate and read below a fourth-grade level. In addition, underemployed and unemployed adults constitute a significant percentage of children who once failed to acquire functional levels of literacy.

Reading failure increases the risk of depression as well as suicidality.

Reading failure increases the risk of depression as well as suicidality. Fuller-Thomson and team (2018) conducted a large representative survey of community-dwelling Canadians, which showed that one in every six women and one in every nine men with specific learning disorders (SLDs) had attempted suicide. Dyslexia or reading disability is the most common SLD, comprising 80% of all diagnosed SLDs. Fuller-Thomson et al. concluded that people with SLDs had 46% higher odds of having ever attempted suicide in comparison with their peers without SLDs, even after controlling for many of the known risk factors for suicide attempts: lifetime history of depression, substance abuse, ADHD, early adversities, age, race, gender, household income and education.

Strong reading skills, on the other hand, have been tied to many personal, social and economic benefits. In a large, population-representative sample from the United Kingdom, reading ability at the early age of seven was linked to socio-economic status at age 42. Participants who had higher reading skills as children had higher incomes, better housing, and more desirable jobs in adulthood. The data suggest, for example, that achieving one reading level higher at age seven was associated with a £5,000 increase in income at the age of 42.

A special category of poor readers

Although no academic skill is more vital than the ability to read, the reality is that many children battle to learn to read, and some never succeed. While there are many causes for reading failure, witnessing children who struggle to break the alphabetic code despite adequate intelligence, and what seems to be sufficient instruction, has been plaguing educators, psychologists and neuroscientists alike for more than a century. These children read slowly and haltingly, even “atrociously” (Fawcett, 2014, p. xiv), and words that they read correctly in one sentence may be misread in a subsequent sentence. Reading aloud may be particularly painful. Spelling may vary from being inconsistent to the bizarre. This phenomenon has been called many names, but most have now been discarded in favor of the terms dyslexia and reading disability. The DSM-5 categorized dyslexia as a “specific learning disorder”. Depending on the definition and diagnostic criteria employed, dyslexia affects from 3% to 20% of the population, and up to 40% experience some type of reading difficulty.

Dyslexia is characterized primarily by reading difficulty in the absence of any profound sensory, neurological and intellectual disorders or socio-cultural factors. As with most disorders, dyslexia occurs on a continuum, varying from mild to severe. The most common subtypes of dyslexia include dysphonetic (also called phonological or auditory), dyseidetic (also named surface and visual) and deep.

Individuals with dysphonetic dyslexia experience difficulty with applying phonics, whereas people with dyseidetic dyslexia are able to read phonically regular words but experience greater difficulty with irregular words — i.e. words like eye, laugh, once and straight that do not have regular, predictable grapheme-phoneme correspondences. Deep dyslexia is used to describe a severe impairment, and is accompanied by other types of reading errors: semantic errors (e.g. street is read as road), visual errors (e.g., badge is read as bandage), derivational errors (e.g., edition is read as editor) and difficulty reading functional words (e.g., as, the, so). Deep dyslexia is often described as an acquired reading disorder due to a brain injury (Mather & Wendling, 2012).

Dyslexia may co-occur with other developmental disorders such as attention deficit hyperactivity disorder (ADHD), dyscalculia or dyspraxia. Dyscalculia, which means inability to calculate, is the most widely used term for disabilities in arithmetic and mathematics. Dyspraxia refers to a developmental disorder that affects fine and gross motor skills, motor planning and coordination.

The discrepancy model

Research has shown that the distinction between the intellectually able dyslexic poor reader and the ‘garden-variety’ poor reader with an equally depressed cognitive profile, is no longer tenable.

Traditionally, dyslexia has been defined in terms of a discrepancy between actual reading performance and what would be expected based on the child’s intelligence. The ‘true dyslexic’ was typically a person who, despite struggling with reading, is above average in intelligence (Elliott, 2015). When children are less intelligent, their reading troubles have been ascribed to their general intellectual limitations.

Research has shown that the distinction between the intellectually able dyslexic poor reader and the ‘garden-variety’ poor reader with an equally depressed cognitive profile, is no longer tenable. Using brain imaging scans, Tanaka et al. (2011) found no differences between the way poor readers with or without dyslexia think while reading. Poor readers of all IQ levels showed significantly less brain activity in six observed areas, such as the left parietotemporal and occipitotemporal regions. These findings were largely replicated by Simos et al. (2014). Despite the wealth of scientific evidence against the use of the discrepancy model, many clinicians and practitioners continue to persist in diagnosing on this basis (Elliott, 2015).


Extreme viewpoints exist about dyslexia, which makes it difficult for parents to know how to best help their child. One view is that dyslexia is a condition that cannot be cured but endured. The British Dyslexia Association (BDA) states that dyslexia “is likely to be present at birth and to be life-long in its effect”. The association and many others like it recommend taking a dyslexia test ― at a cost ― and provide advice about how to cope with dyslexia and gain access to the special study allowances and benefits available for diagnosed dyslexics. Another opinion is that dyslexia is a gift. According to Eide and Eide (2012) and Davis (1997), the mental function that causes dyslexia is a gift in the truest sense of the word: a natural ability, a talent. It is something special that enhances the individual. In his book, The Gift of Dyslexia, Davis wrote (p. 3):

Usually when people hear the word dyslexia they think only of reading, writing, spelling and math problems a child is having in school . . . but the learning disability is only one face of dyslexia. Once as a guest on a television show, I was asked about the “positive” side of dyslexia. As part of my answer, I listed a dozen or so famous dyslexics. The hostess of the show then commented, “Isn’t it amazing that all those people could be geniuses in spite of having dyslexia.” She missed the point. Their genius didn’t occur in spite of their dyslexia, but because of it!

Despite such claims, a study by Łockiewicz et al. (2014) suggests that the success of high-performing adults with dyslexia is unlikely to be a function of particular cognitive factors such as superior visuo-spatial abilities and creativity (often claimed to be strengths of people with dyslexia). Rather, outstanding success seem to depend more on personality and motivational factors.

In The Dyslexia Debate, Elliott and Grigorenko (2014) argue that a diagnosis of dyslexia adds little value.

Some say diagnoses of dyslexia are a complete waste of time — and even that dyslexia is a myth. In The Dyslexia Debate, Elliott and Grigorenko (2014) argue that a diagnosis of dyslexia adds little value. While many believe that dyslexia assessments are scientifically rigorous, a diagnosis of dyslexia offers little to no benefit for guiding the nature of any intervention. The term dyslexia, according to them, confuses rather than clarifies and should be discontinued. They quote Stanovich who said, “retire the term dyslexia permanently [because] . . . whatever small purpose it serves is swamped by the confusion it causes” (Stanovich, 2012, as cited by Elliott & Grigorenko, 2014).

Graham Stinger (2009), a British Member of Parliament, caused international outrage when he described dyslexia as “a cruel fiction . . . no more real than the 19th-century scientific construction of ‘the æther’ to explain how light travels through a vacuum. The sooner it is consigned to the same dustbin of history, the better.” He argued that the reason why so many children struggled with literacy was that they had been failed by the education “establishment.” Rather than admitting that poor instruction was at fault, a brain disorder called dyslexia had been invented. For Stringer, “to label children as dyslexic because they’re confused by poor teaching methods is wicked.” According to Miller (2015), the biggest cause of reading difficulty is the unsystematic and unscientific teaching of reading. As a result, children are let down twice by the educational system: first by not being properly taught and then pathologized with the “diagnosis” of dyslexia when they fail.

Snowling disagrees. She has been quoted as saying (Womack, 2007):

No one in the field of education would deny that there are myths surrounding dyslexia, but this does not mean that dyslexia is a myth. There is strong scientific evidence concerning the nature, causes and consequences of dyslexia. Some people find learning to read and write a trivial matter whereas others, notably children with dyslexia, have extreme difficulty.


Delve deeper

Learn about dyslexia’s history

The term dyslexia was introduced in 1884 by the German ophthalmologist, Rudolf Berlin, in “Over dyslexie.” He coined it from the Greek words dys meaning ill or difficult and lexis meaning word, and detailed his observations of six patients with brain lesions who had full command over verbal communications but had lost the ability to read. Read more…

What is dyslexia in the present world? What are the symptoms?

Depending on the definition and diagnostic criteria employed, dyslexia affects from 3% to 20% of the population, and up to 40% experience some type of reading difficulty. Today dyslexia refers to a difficulty in learning to decode (read aloud) and to spell. Dyslexia is best thought of as a continuum, not a distinct category, and there are no clear cut-off points. Symptoms may include weakness in phonological processing, directional confusion, and sequencing difficulties. Read more…

What causes dyslexia?

Most problems can only be solved if one knows what causes that particular problem. A viable point of departure would thus be to ask: what causes dyslexia? We look at genetic influences, cognitive deficits and why they matter, as well as brain differences. Read more…

Are there different types of dyslexia?

The most common subtypes of dyslexia include dysphonetic (also called phonological or auditory), dyseidetic (also named surface and visual), and deep. While some scholars assert there are more types, others say research does not support the use of dyslexia subtypes to guide assessment and intervention. Read more…

A real problem, but one that can be dealt with

Meet Maddie, who has been diagnosed with severe dyslexia, moderate dyscalculia, and ADHD. Read how she improved from the 1st to the 55th percentile in reading after doing Edublox intensively for 35 weeks, or watch the video below. Read more…


Key takeaways


NEXT: Page 2: Dyslexia’s history

Authored by Susan du Plessis (B.A. Hons Psychology; B.D.) who has 30+ years’ experience in the LD field.
Page last reviewed: May 21, 2021.
Next review due: May 21, 2023.

References and sources:

Abrams, L. (2013, May 9). Study: Math skills at age 7 predict how much money you’ll make. The Atlantic. Retrieved March 8, 2020 from https://www.theatlantic.com/health/archive/2013/05/study-math-skills-at-age-7-predict-how-much-money-youll-make/275690/

American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.). https://doi.org/10.1176/appi.books.9780890425596

Carvalho, P. (2015). Youth unemployment in Australia. (Report No. 7). Retrieved from the The Centre for Independent Studies website: https://www.cis.org.au/app/uploads/2015/11/rr7.pdf

Daniel, S. S., Walsh, A. K., Goldston, D. B., Arnold, E. M., Reboussin, B. A., & Wood, F. B. (2006). Suicidality, school dropout, and reading problems among adolescents. Journal of Learning Disabilities, 39(6), 507-514.

Davis, R. (1997). The gift of dyslexia. New York: Berkley Publishing Group.

Dunson, W. E. (2013). School success for kids with dyslexia & other reading disabilities. Waco, TX: Prufrock Press Inc.

Eide, B. L., & Eide, F. F. (2012). The dyslexia advantage. New York: Penguin Books Ltd.

Elliott, J. G. (2015). The dyslexia debate: Actions, reactions, and over-reactions. Psychology of Education Review, 39(1), 6-16.

Elliott, J. G., & Grigorenko, E. L. (2014). The dyslexia debate. Cambridge: Cambridge University Press.

Fawcett, A. (2014). Preface. In A. Fawcett, & R. Nicolson (Eds.), Dyslexia in children: Multidisciplinary perspectives (pp. xiii-xx). London: Routledge.

Fern-Pollak, L., & Masterson, J. (2016). Dyslexia and the English writing system. In V. Cook & D. Ryan (Eds.). The Routledge handbook of the English language (pp. 223-34). New York: Routledge.

Fuller-Thomson, E., Carroll, S. Z., & Yang, W. (2018). Suicide attempts among individuals with specific learning disorders: An underrecognized issue. Journal of Learning Disabilities, 51(3), 283-292.

Harpine, E. C., & Reid, T. (2009). Enhancing academic achievement in a hispanic immigrant community: The role of reading in academic failure and mental health. School Mental Health, 1, 159-170.

Kalanje, E. S. (2011). Identifying first graders at risk of reading and writing difficulties. Åbo, Finland: Åbo Akademi University Press.

Kern, M. L., & Friedman, H. S. (2009). Early educational milestones as predictors of lifelong academic achievement, midlife adjustment, and longevity. Journal of Applied Developmental Psychology, 30(4), 419-430.

Lallier, M., Lizarazu, M., Molinaro, N., Bourguignon, M., Ríos-López, P., & Carreiras, M. (2018). From auditory rhythm processing to grapheme-to-phoneme conversion: How neural oscillations can shed light on developmental dyslexia. In T. Lachmann, & T. Weis (Eds.). Reading and dyslexia (pp. 141-157). Cham, Switzerland: Springer.

Łockiewicz, M., Bogdanowicz, K. M., & Bogdanowicz, M. (2014). Psychological resources of adults with developmental dyslexia. Journal of Learning Disabilities, 47(6), 543-555.

Logan, S., Medford, E., & Hughes, N. (2011). The importance of intrinsic motivation for high and low ability readers’ reading comprehension performance. Learning and Individual Differences, 21, 124-128.

Mather, N., & Wendling, B. J. (2012). Essentials of dyslexia assessment and intervention. Hoboken, NJ: Wiley.

Maughan, B., Rowe, R., Loeber, R., & Stouthamer-Loeber, M. (2003). Reading problems and depressed mood. Journal of Abnormal Child Psychology, 31(2), 219-229.

Miller, J. F. (2015). Do you read me? Learning difficulties, dyslexia, and the denial of meaning. London: Karnac Books.

Ritchie, S. J., & Bates, T. C. (2013). Enduring links from childhood mathematics and reading achievement to adult socioeconomic status. Psychological Science, 24(7), 1301-1308.

Scarpetta, S., Sonnet, A. & Manfredi, T. (2010). Rising youth unemployment during the crisis: How to prevent negative long-term consequences on a generation? OECD Social, Employment and Migration Working Papers, 106. https://doi.org/10.1787/5kmh79zb2mmv-en.

Shaywitz, S. (2005). Overcoming dyslexia. New York: Vintage Books.

Simos, P. G., Rezaie, R., Papanicolaou, A. C., & Fletcher, J. M. (2014). Does IQ affect the functional brain network involved in pseudoword reading in students with reading disability? A magnetoencephalography study. Frontiers in Human Neuroscience, 7(932). https://doi.org/10.3389/fnhum.2013.00932

Slaten, C. D., Elison, Z. M., Hughes, H., Yough, M., & Shemwell, D. (2015). Hearing the voices of youth at risk for academic failure: What professional school counselors need to know. The Journal of Humanistic Counseling, 54(3), 203-220.

Stinger, G. (2009, January 12). Dyslexia is a myth. Retrieved July 15, 2019 from http://old.manchesterconfidential.co.uk/News/Dyslexia-is-a-myth

Tanaka, H., Black, J. M., Hulme, C., Stanley, L. M., Kesler, S. R., Whitfield-Gabrieli, S., … Hoeft, F. (2011). The brain basis of the phonological deficit in dyslexia is independent of IQ. Psychological Science, 22(11), 1442-1451.

Womack, S. (2007, September 13). Dyslexia: Complex medical condition, or myth. Tthe Telegraph. Retrieved March 7, 2020 from https://www.telegraph.co.uk/news/uknews/1562969/Dyslexia-complex-medical-condition-or-myth.html

Wydell, T. N., & Fern-Pollak, L. (2012). Preface. In T. N. Wydell, & L. Fern-Pollak (Eds.) Dyslexia – A comprehensive and international approach (pp. IX-XI). Rijeka, Croatia: InTech.