History of English Dyslexia

The history of dyslexia stretches back more than a century, from early clinical observations about puzzling reading failures to today’s neuroscientific understanding of phonological processing. Tracing this history helps explain why the field took so long to reach consensus and why some harmful myths persisted for decades.

“Word Blindness”: The Late 19th Century

The first systematic clinical descriptions of reading difficulty appeared in the late 19th century among physicians treating patients who had lost the ability to read after brain injury — a condition called acquired alexia. In 1896, a British ophthalmologist named W. Pringle Morgan published the case of a 14-year-old boy named Percy who was bright and capable in every respect except reading. Morgan called the condition “congenital word blindness,” borrowing the language of the acquired alexia cases he knew from the neurological literature.

Around the same time, James Hinshelwood, a Scottish ophthalmologist, described multiple cases of children with severe reading difficulty in otherwise intellectually capable individuals. He argued that the condition was neurological in origin and emphasized that these children needed specialized instruction, not moral correction.

The Mid-20th Century: Samuel Orton

In the 1920s and 1930s, American neurologist Samuel Torrey Orton contributed the most influential early theory of dyslexia. Orton observed that many struggling readers reversed letters (b/d, p/q) and read words backwards. He proposed that the condition arose from incomplete cerebral dominance — a failure of one hemisphere to fully take control of language. He called the condition “strephosymbolia” (twisted symbols).

Though Orton’s specific theory of cerebral dominance was later revised, his practical contributions were lasting. He collaborated with educator Anna Gillingham to develop a multisensory, phonics-based teaching approach — the Orton-Gillingham method — that remains a foundation of structured literacy instruction today.

The Phonological Revolution

The most significant conceptual shift came in the latter half of the 20th century, driven by researchers including Isabelle Liberman and her colleagues at the Haskins Laboratories in New Haven, Connecticut. Their work established that the core difficulty in dyslexia is not visual (letters are not seen backwards) but linguistic — specifically, a weakness in representing and manipulating the sound segments of spoken language, called phonemes.

This phonological model was confirmed by converging evidence from cognitive psychology, genetics, and eventually brain imaging. It explained why dyslexia is a reading disability specifically (not a visual problem), why training in phoneme awareness helps, and why the condition runs in families.

Sally Shaywitz’s research at Yale built directly on this phonological foundation, adding the critical dimension of brain imaging to show precisely which neural systems are involved.

Based on “Overcoming Dyslexia” by Sally Shaywitz, M.D. (2020 edition)