History of dyslexia

Word blindness

The story of dyslexia begins in the late 19th century. In 1877, German physician Adolf Kussmaul described “word blindness” (Wortblindheit) in a patient who had lost the ability to read despite intact vision and intelligence. This was an acquired condition, resulting from brain injury, but it established the principle that reading could be specifically affected while other cognitive abilities remained intact.

The breakthrough for what we now call dyslexia came in 1896, when British ophthalmologist W. Pringle Morgan published a case report in the British Medical Journal. He described a 14-year-old boy named Percy who was “the smartest lad in the school” yet could not learn to read. Morgan called this “congenital word blindness”, distinguishing it from the acquired form: Percy had never been able to read, despite being bright and well-taught.

This was the first documented case of developmental dyslexia in English medical literature. Morgan’s careful observation that the difficulty was specific to reading, not a reflection of general intelligence, was remarkably prescient.

The visual theory and its consequences

For much of the early 20th century, dyslexia was understood primarily as a visual problem. American neurologist Samuel Orton proposed in the 1920s that dyslexia was caused by “strephosymbolia” (twisted symbols), resulting from incomplete cerebral dominance. He believed that dyslexic people saw letters and words reversed or mirrored.

Orton’s theory was influential but largely incorrect. It led to interventions focused on visual training and, harmfully, forced right-handedness in left-handed children, on the theory that mixed laterality caused reading problems. These interventions were ineffective and sometimes damaging.

The persistent myth that dyslexia is about “seeing letters backwards” traces directly to Orton’s work. While some dyslexic people do occasionally reverse letters, this is not the core feature and is common in all young readers.

The phonological revolution

The 1970s and 1980s brought a fundamental shift in understanding. Researchers including Isabelle Liberman and later Sally Shaywitz demonstrated that dyslexia is primarily a difficulty with phonological processing: the ability to recognise, manipulate, and map the sounds of language onto written symbols.

This was a paradigm shift. Dyslexia was not about vision. It was about how the brain processes the building blocks of language. Phonological awareness, the ability to hear and work with the individual sounds in words, was consistently found to be weaker in dyslexic readers, regardless of intelligence, motivation, or teaching quality.

Neuroimaging studies from the 1990s onwards confirmed this understanding, revealing that dyslexic brains show different patterns of activation during reading tasks, particularly in left hemisphere language regions. Dyslexia became understood as a neurological difference in how the brain organises language processing, not a deficit of intelligence or effort.

From deficit to difference

The language around dyslexia has shifted significantly over the past few decades. “Word blindness” gave way to “reading disability”, which gave way to “specific learning difficulty”, which is now increasingly framed within the neurodiversity paradigm as a neurological difference.

This reframing matters. For over a century, many people with dyslexia were labelled as lazy, stupid, or unmotivated. They were punished for what they could not do. The attribution of reading difficulty to a character flaw rather than a neurological difference caused lasting harm to self-esteem, educational outcomes, and life chances.

Modern understanding acknowledges that dyslexia involves genuine difficulties with reading and written language, while also recognising the strengths that often accompany it: strong visual-spatial reasoning, creative thinking, and the ability to see patterns and connections that others miss.

Dyslexia in the UK

The UK has a relatively strong framework for recognising dyslexia in education, with the British Dyslexia Association playing an influential role in advocacy and support since 1972. Dyslexia is recognised within the SEND (Special Educational Needs and Disabilities) framework, and schools have a legal obligation to make reasonable adjustments.

However, access to assessment varies significantly by region and by socioeconomic background. Families who can afford private assessment often secure support more quickly than those relying on school or NHS provision. This inequality means that dyslexia, like many neurodevelopmental conditions, is more readily identified in those with greater resources.

Further reading on neurobetter

• Dyslexia - overview
• Understanding diagnosis
• Co-occurrence
• The language of neurodiversity

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