Does dyslexia even exist?

11 minute read

The experts can't agree on a definition for dyslexia, leaving the door open for some to question its existence

People who have been told they have dyslexia often describe letters “swimming” before their eyes when they read, or lines of text mischievously switching places.

In the broader community, there exists a fuzzy impression of what the term may mean, but it’s often perceived as a lifelong reading problem that can affect even the best and brightest among us.

This popular myth has woven dyslexia into tales of fame and wealth, including the likes of scientist Albert Einstein, celebrity chef Jamie Oliver, businessmen Richard Branson and Kerry Packer, and popular crime novelist Agatha Christie.

But despite the perception, there is no agreement among experts as to what dyslexia even is, nor is there a universal definition of dyslexia.

Some experts use the word specifically to refer to around 1% to 3% of the population who experience reading difficulties throughout their lifetime, despite having normal cognitive abilities and access to high quality, evidence-based interventions.

Other experts use dyslexia as a synonym for “poor reading”. People with dyslexia, according to this group, have reading abilities in the bottom 5% to 10% of the population.  And for most people diagnosed with dyslexia, reading difficulties can cast a long shadow in their lives.

“There’s nothing trivial about having reading problems across your lifespan,” says Professor Pamela Snow, a psychologist and the head of the Rural Health School at La Trobe University.

Yet another camp of experts has stopped using the word dyslexia because they say it is too muddy a term to be clinically useful.

And then there’s the Australian Dyslexia Association, which defines dyslexia as a “learning difference” that is characterised by difficulties with word recognition and “often unexpected in relation to other cognitive abilities”. This definition appeared in the 2010 Australian Dyslexia Working Party report to the federal government.

It seems that anything goes when it comes to describing dyslexia.

“It creates a fair bit of confusion,” Professor Genevieve McArthur, the head of the Department of Cognitive Science at Macquarie University, says. “People use [the word] to refer to quite different things. And there is really no right and wrong really.”

The dyslexia debate

With experts and dyslexia advocates unable to pin down a definition, it was unsurprising that researchers decided to stir the pot. In a provocative book called The Dyslexia Debate, Professor Julian Elliot of Durham University in the UK and Elena Grigorenko argued that dyslexia was a meaningless term with a limited scientific basis.

The book, published in 2014, claimed that efforts to diagnose a small group of children with dyslexia diverted vital resources away from early intervention for all children with reading problems.

Their views elicited much hate mail from parents of children who had been diagnosed with dyslexia. It also provoked a curt response from the International Dyslexia Association. “Those who tamper with commonly understood language do so at their peril,” Hal Malchow, the then president-elect, warned.

Psychologists and researchers are the first to admit the term dyslexia is imprecise. In an article published in The Conversation, Australian experts, including Professor Anne Castles and educational psychologist Mandy Nayton, said many of the claims made in The Dyslexia Debate were correct. But they argued against abandoning the term dyslexia.

Professor Castles, the deputy director and reading program leader for the ARC Centre of Excellence in Cognition and its Disorders, said there were pros and cons to using the term, but that on balance, it remained useful.

Yes, making a diagnosis of dyslexia requires clinicians to choose an arbitrary cut-off point along a spectrum of reading abilities, she says. But this is also necessary in conditions such as hypertension or obesity. Besides, a diagnosis of dyslexia attracts attention, funding and support to people who fall on the extremes of the spectrum, she argues.

Ms Nayton, an educational psychologist and the president of the Australian Federation of SPELD Associations, tends to agree that dyslexia exists.

“The evidence available to us suggests that [some students] do have an underlying neurobiological developmental disorder that makes it particularly difficult for them to acquire strong literacy skills,” she says.

However, all students at risk of literacy failure need to be identified and given support as soon as possible. “[We] treat first and diagnose second,” she says.

Another group of experts, including Professor Snow, argue against diagnosing dyslexia.

Professor Snow says it is unhelpful to advantage one child with poor reading skills over another by giving their condition a medical label that attracts special services.

“The other child’s reading difficulties are just as real and require attention just as much, but because they don’t get the diagnostic sexy-sounding label, they are likely to be left behind,” she says.

A child that has had poor reading instruction for the first three years of school is functionally dyslexic. “What does it matter whether they have an underlying brain disorder or they haven’t had good instruction?” she says. “They need intervention.”

Professor Snow argues that dyslexia is not a diagnostically robust term. “I don’t think it is possible on clinical grounds to make a meaningful distinction,” she says. “We don’t necessarily know why an individual child has poor reading skills.”

Some children with poor reading abilities will have low comprehension skills or limited vocabulary, others will miss out on good quality teaching during the first three years of school and become “instructional casualties”.

Children who are disadvantaged due to their socio-economic circumstances may also need very rigorous, explicit reading instruction.

“There is probably a very small percentage of children who have an underlying brain disorder that means, in spite of the best instruction and not having a diagnosable developmental disorder, they specifically struggle to read,” says Professor Snow. “I would say that’s around less than 1% of children.”

Professor McArthur’s department at Macquarie University in Sydney opts out of the debate about whether dyslexia can be diagnosed.

The department prefers to use the term “poor reading” because the word dyslexia carries assumptions about the underlying cause of the problem. And how can researchers claim to know the cause of one child’s reading difficulty, Professor McArthur asks, when the distal causes of dyslexia are little more than theories and “very controversial” ones at that?

“There are a million different hypotheses,” she says.

The extremes of human experience often get a medical label, sometimes without much scientific justification. Why do we label people with poor reading skills as having a disorder while people who can only draw stick figures, sing out of tune or fail to read maps are considered perfectly normal?

“Perhaps a good argument for not using these terms is that if the same applied to your skills in geography no one would care,” says Professor Castles. “It is good to keep that perspective. Reading is just one aspect of learning and people that struggle can have outstanding strengths in many other areas.”

While there is no easy fix for children with dyslexia, there are ways to ensure they get the same access to the school curriculum
While there is no easy fix for children with dyslexia, there are ways to ensure they get the same access to the school curriculum


While some experts disagree with the use of the term dyslexia, the DSM-5, the US standard classification of mental disorders used by mental health professionals, includes clinical criteria for diagnosis, and recommends putting all children with poor reading through a six-month intervention targeted at the area of weakness.

“And then if the child continues to struggle or has only progressed with that intervention at a very slow rate … that’s when you would start to use the term dyslexia,” Ms Nayton says.

The DSM-5 uses four criteria for dyslexia diagnosis:

– The reading difficulty is ongoing despite long-term interventions;

– The student’s reading ability is substantially below their peers on standardised psychometric tests that assess reading accuracy, rate, and comprehension;

– The difficulty arises in the school-age years; and

– The problem cannot be better accounted for by other factors.

“So with those four criteria in mind I think we can actually be quite specific about what dyslexia is,” Ms Nayton says.

From this point, things get even more controversial.

The Australian Dyslexia Association breaks down dyslexia into four subtypes. Other groups use three subgroups.

And some experts do not use any subtypes in a clinical context.

Breaking dyslexia down into categories is an attempt to describe the various proximate causes of poor reading and thereby indicate which intervention might be most effective.

People with phonological dyslexia (dysphonesia) find it difficult to read because they struggle to sound out words. When encountering a new word or a nonsense word they may be unable to pronounce it because they cannot process the letters as units of sound (phonemes).

The other core component of reading is being able to recognise whole words. People with surface dyslexia (dyseidesia) find this difficult. Words that do not follow the normal phonics rules of English, such as “yacht”, might trip them up.

Mixed dyslexia is where both phonological dyslexia and surface dyslexia occur together.


By its very nature, dyslexia persists over a lifetime. While reading difficulties never completely disappear, there is broad agreement about the types of interventions that can help.

Training programs, such as MultiLit or SoundWrite, that specifically build up phonological awareness or whole word recognition by breaking language down into simple components are successful in training children to read.

Two recent randomised controlled trials led by Professor McArthur demonstrated the reliability of both phonics and sight word training in treating poor readers.1,2 

“The intervention must be delivered in a very structured, systematic, cumulative and explicit way with lots of repetition,” Ms Nayton says.

A well-trained teacher working one-on-one or in small groups is essential. Decodable books, which slowly introduce letter-sound relationships, can also be useful.

“What you are encouraging [children] to do is decode words,” Ms Nayton says. “You are not encouraging them to guess from the context, guess from the pictures on the page or guess from the first couple of letters of the word. You are actually teaching them the actual skill of reading so that, as they are facing more and more complex language, they are actually decoding.”

These methods work for all children with poor reading, including those that have fallen behind for other reasons, such as poor attendance at school.  “Whether or not you apply the label  makes absolutely no different to the kind of interventions that are needed to bring children’s reading levels up,” Professor Snow says.

There is a popular belief that tinted reading glasses are beneficial for some people with reading impairments but there is no evidence to support their use. This is true, also, of Omega 3 oils, and exercise regimes, Ms Nayton says.

While some people who have been diagnosed with dyslexia swear by Comic Sans as the easiest typeface to read, a study published in The Annals of Dyslexia in 2016 showed there was no benefit associated with switching from Times New Roman to the specially designed font, OpenDyslexic.

It seems there is no easy fix for children with dyslexia. But there are ways to ensure that they can get access to the curriculum on the same basis as their peers.

Assistive technology such as eBooks, voice recognition software or scanning pens (which can make written words audible) can help stop children with dyslexia from falling behind, Ms Nayton says.

Dyslexia is recognised in Australia under the Disability Discrimination Act 1992 and students with dyslexia are entitled to disability provisions such as extra time or resources during exams.

“There the important thing is to get them on an equal playing field,” says Professor Castles.

But compensations must be appropriately matched and this is difficult to achieve when not all reading problems are the same.

For adults with dyslexia, the fight against discrimination can be a bitter one.

In December last year, three NSW universities rejected severely dyslexic student James Bond because he required a scribe to complete his PhD proposal.

Many adults learn to hide their problems with reading to avoid discrimination.

“We live in a society where literacy is of absolutely fundamental importance to being part of the social and economic mainstream,” says Professor Snow.

In today’s information economy, reading is the key that unlocks everything.


1. J Learn Disabil. 2015 Jul-Aug;48(4):391-407.

2. PeerJ. 2015 May 5;3:e922.

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