Dyslexia is a common learning difficulty. Prevalence rates vary depending on how it is defined; reported rates range from of 5 to 20 percent (Butterworth & Kovas, 2013; Siegel, 2006; Shaywitz, 2005).
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 used it to describe a specific disturbance of reading in the absence of pathological conditions in the visual organs. In a later publication, in 1887, Berlin stated that dyslexia, “presuming right handedness,” is caused by a left-sided cerebral lesion. He spoke of “word-blindness” and detailed his observations with six patients with brain lesions who had full command over verbal communications but had lost the ability to read (Berlin 1884 & 1887, as cited by Opp, 1994).
Berlin himself had been influenced by the writings of another German, Adolph Kussmaul, a Professor of Medicine at Strassburg. Kussmaul noticed that several of his stroke patients could not read properly and regularly used words in the wrong order. He introduced the term word blindness to describe their difficulties. This condition became known as acquired dyslexia.
Developmental dyslexia, on the other hand, refers to the failure to learn to read competently, and was first defined in 1896 by Pringle Morgan in the British Medical Journal. Morgan called it “congenital word blindness,” and reported on a 14-year-old student who attended a well-respected school where he had been a pupil since the age of seven. The boy could not read a single word correctly out of an easy child’s book, with the exception of “and,” “the,” “of,” “that,” etc. Morgan described the boy as “bright and of average intelligence in conversation. His eyes are normal, there is no hemianopsia, and his eyesight is good. The schoolmaster who has taught him for some years says that he would be the smartest lad in the school if the instruction were entirely oral” (p. 1378).
Research into acquired and congenital word-blindness developed both in Britain by James Hinshelwood, an optic surgeon from Glasgow, and in the USA by Samuel Torrey Orton, a neurologist and neuropathologist. Hinshelwood (1917), expanding on the work of Berlin and Morgan, attempted to identify both conditions and concluded that while acquired word-blindness is a neurological condition owing to brain injury, congenital word-blindness is hereditary, but remediable and more common in boys.
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Orton was arguably the key figure in setting the stage for the study of reading disabilities in the United States. The primary professional society devoted to reading disabilities, the International Dyslexia Association, was originally named the Orton Dyslexia Society.
In 1919, Orton was hired as the founding director of the State Psychopathic Hospital in Iowa City, Iowa, and chairman of the Department of Psychiatry at the University of Iowa College of Medicine. In 1925, he set up a 2-week mobile clinic in Greene County, Iowa to evaluate students referred by teachers because they “were retarded or failing in their school work.” Orton found that 14 of the students who were referred primarily because they had great difficulty in learning to read, in fact had near-average, average, or above-average IQ scores. Hinshelwood had also noted that many of his cases of congenital word-blindness were intelligent, but with the advent of IQ tests Orton was able to lend a certain degree of objectivity to this notion, and whereas Hinshelwood had bristled at the notion that one per thousand students in elementary schools might have “word-blindness,” Orton offered that “somewhat over 10 percent of the total school population” had reading disabilities (Orton 1925 & 1939, as cited by Hallahan & Mercer, 2002).
Orton’s study of reading difficulties in children led him to hypothesize that developmental dyslexia is the production of both neurological and environmental processes, which will respond to and could be treated through specific training methods aimed at dyslexic learning needs. He linked mixed dominance to the major symptoms he frequently observed in the clinic: (a) reversals of letters such as p and q and b and d; (b) confusion of palindromes such as was and saw; (c) reading from right to left, manifested by reversals of paired letters, syllables within words, or whole words within sentences; and (d) a propensity to mirror read and/or write. From these observations he proposed his “strephosymbolia,” or twisted symbols theory, and suggested that dyslexics had a deficient visual perception of letters caused by the inheritance of mixed cerebral dominance (Hallahan & Mercer, 2002; Guardiola, 2001; Macdonald, 2009).
As a result of Orton’s research, dyslexia passed from the medical to educational ownership. This led to it being ‘treated’ by educational development rather than medical intervention (Macdonald, 2010).
The term word blindness is now obsolete. This is also true of such less known and infrequently used terms as word amblyopia, thypholexia, amnesia visualis verbalis, analfabetia partialis, bradylexia, script-blindness, psychic blindness, symbolia confusion, primary reading retardation and developmental reading backwardness. Even the term coined by Orton, strephosymbolia, never caught on, despite the popularity of his theory (Gjessing & Karlsen, 1989). Most of these terms have now been discarded in favor of the terms dyslexia, reading disability and learning disability, with learning disabilities (LD) as the umbrella term for a variety of learning difficulties, including dyslexia. Dyslexia is categorized as a “specific learning disorder” in the DSM-5, published in 2013 (American Psychiatric Association).
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Butterworth, B., & Kovas, Y. (2013). Understanding neurocognitive developmental disorders can improve education for all. Science, 340(6130): 300-5. https://doi-org.uplib.idm.oclc.org/10.1126/science.1231022
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Hallahan, D.P., & Mercer, C.D. (2002). Learning disabilities: Historical perspectives. In R. Bradley, L. Danielson, & D. P. Hallahan (Eds.). The LEA series on special education and disability. Identification of learning disabilities: Research to practice (pp. 1-67). Mahwah, NJ, US: Lawrence Erlbaum Associates Publishers.
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Macdonald, S.J. (2009). Towards a sociology of dyslexia. Exploring links between dyslexia, disability and social class. Germany: VDM Verlag Dr. Müller.
Macdonald, S.J. (2010). Crime and dyslexia: A social model approach. Germany: VDM Verlag Dr. Müller.
Morgan, W.P. (1896). A case of congenital word blindness, British Medical Journal, 2(1871): 1378.
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Shaywitz, S. (2005). Overcoming dyslexia: A new and complete science-based program for reading problems at any level. New York: Vintage Books.
Siegel L.S. (2006). Perspectives on dyslexia. Paediatrics & Child Health, 11(9): 581-7.