What is Dyslexia?


A specific (and the most common) kind of learning disability

The most common reason for a student to need special education services is because they have some form of learning disability.  Within that broad term of “specific learning disability,” the most common area of learning disability is reading-related.  And within the reading skills, the most common breakdown occurs within basic reading skills, which strongly impacts reading fluency.  Dyslexia, at its core, is this breakdown in basic reading skills, which almost always impacts reading fluency and spelling, and sometimes impacts reading comprehension.

“Dys” + “lexia”

The word dyslexia comes from two Greek roots: dus which means “hard, bad, difficult” and lexis which means “speech, word.”  Literally, dyslexia means “difficulty with words” or, as it is often interpreted, “difficulty with reading.”  Dyslexia was first identified in the late 1800s, and at that point, it was also called “word blindness.” That was the very early stage of realizing that some children who are average in every other way simply failed to learn to read.    These children were intelligent, and some did quite well in math and in subjects that were taught orally, but they made little to no progress in reading.  At times, they were dismissed from school, as no one knew how to teach them.

Connecticut Longitudinal Study

A breakthrough in dyslexia research finally came in the late 1980s and early 1990s with the Connecticut Longitudinal Study.  Directed by Bennet & Sally Shaywitz, the study followed 445 children from kindergarten into young adulthood.  These students were carefully monitored and evaluated in various areas across their educational development. The goal of the study was to gain a better understanding of how reading develops, what separates a good reader from a poor reader, how prevalent reading disabilities are, and other related questions.  This study has become the cornerstone of our current understanding of dyslexia, and it has provided a scientific basis for understanding dyslexia that is still sorely lacking in many of the other learning disabilities.  Space is too limited here to do justice to this research, but the book Overcoming Dyslexia by Sally Shaywitz provides an excellent summary of the research, a definition of dyslexia, and guidelines for appropriate dyslexia interventions.

Phonological awareness: the key to dyslexia

Phonological awareness is the awareness of the sounds within speech.  When we speak, words come out as chunks or bursts of sound, with the individual sounds in words overlapping.  For instance, when we say “cat,” it does not come out as /c/-/a/-/t/ in distinct, separate sounds; rather, our very flexible tongues co-articulate, or overlap, the sounds, so that the word is one complete burst.  For about 80% of children, sound awareness develops fairly automatically, and by the end of kindergarten, they can tell you the beginning and ending sounds of words, recognize and provide rhyming words, and even remove specific sounds or syllables from words when told to (For example: “Say cowboy. Now say it again, but don’t say cow.” “Boy”).  But for about 20% of children, this phonological awareness fails to develop sufficiently.  This phonological awareness skill is the single largest predictor of which children will learn to read fluently.

Phonological awareness, and thereby reading skills, develop on a continuum.  In other words, there is no distinct gap separating students with good phonological awareness skills and those with weak skills—there are students at every point of the spectrum.  In the Connecticut study, approximately 20% of students—1 in 5—failed to develop appropriate reading skills for their grade, age, or ability.  However, only about 1/3 of these had been identified by their school as having difficulties with reading and were receiving help.

Schools and teachers desperately need to learn how to recognize the signs of this common academic need.


Prior article on prevalence of special education. https://en.wikipedia.org/wiki/History_of_dyslexia_research Information in this paragraph, as well as some of the information in the preceding paragraph, is taken from Overcoming Dyslexia. Shaywitz, S. (2003).  Overcoming dyslexia: A new and complete science-based program for reading problems at any level. New York: Vintage Books. Page 30.

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