What is dyslexia?

What is dyslexia?

The International Dyslexia Association defines dyslexia in the following way “Dyslexia is a specific learning disability that is neurobiological in origin. It is characterized by difficulties with accurate and/or fluent word recognition and by poor spelling and decoding abilities. These difficulties typically result from a deficit in the phonological component of language that is often unexpected in relation to other cognitive abilities and the provision of effective classroom instruction. Secondary consequences may include problems in reading comprehension and reduced reading experience that can impede growth of vocabulary and background knowledge.”

That is quite a word salad though.  Sometimes I feel like we ironically use the most difficult words we can find to read in order to describe reading difficulties.  If you feel like you need a definition for the definition, read on.  I have you covered.

1.  "Neurobiological in origin"

This means that dyslexia is something that you are born with.  It is a part of your biology.  In fact, it is fairly common for reading difficulties to be inherited from a parent or grandparent.

2.  "a deficit in the phonological component of reading that is often unexpected in relation to other cognitive abilities"

When you read "deficit in the phonological component of reading" it means is that dyslexia is nearly always, though not always, caused by problems hearing and manipulating the spoken sounds in words.  This goes back to the phonemic awareness component of reading described above.  If we can't isolate and manipulate the sounds in words then spelling and reading them is mostly impossible.  Have you ever seen a person who is new to reading spell the word "last" as "lat" or the word "get" as "git"?  These are phonological errors.  They aren't hearing both the /s/ and the /t/ in last  and they are mishearing the /e/ as /i/ in "get".  These are the kinds of errors that we often see in the spellings of people who have dyslexia. This is especially true when these errors persist after kindergarten and first grade.

The unexpected part of this definition is a little more complex and controversial.  It turns out that unless we are talking about very extreme cases, IQ and decoding aren't all that predictive of each other.  Students who have lower IQs can often still learn to read and spell fairly well.  They tend to struggle more with comprehension. Equally, a student with a lower IQ can absolutely also have dyslexia.  Students with higher IQs can absolutely struggle with decoding and spelling.  Equally, Dyslexia occurs quite often with other challenges including dyscalculia, ADHD, and many others.  That a student has ADHD, dysgraphia, or any number of other challenges does not mean that they do not also have dyslexia.  That said, for a student to have dyslexia there has to be some deficit that can't be explained by other biological factors.  For example, I have had students who had medical issues which prevented them from tracking words with their eyes.  While this initially looked like dyslexia, these students often responded very quickly to interventions once the medical challenge with their eyes was brought under control because these students did not actually have any challenges with their phonics or phonological awareness.  Once their eyes were physically capable of reading, they learned to read quickly and easily with direct instruction. Although they still required an intensive intervention because they were behind in reading, they did not have dyslexia.

3.  What does all the rest of that definition mean?

The rest of the definition has two big ideas.  The first is that a student can only be said to have dyslexia if they have been exposed to effective classroom instruction and the deficits still persist.  This is because there is no way to know whether a student who has not been taught to read has dyslexia. We would expect that a person who has not been taught to read would struggle to read.  They have never been taught how.  We only begin to suspect dyslexia when we teach them to read and notice that that they still struggle.

The second is that while dyslexia often begins with isolated deficits, when we don't provide effective instruction and support it doesn't stay isolated.  It can spiral into all sorts of other problems.  This is called the Matthew Effect.  The Matthew Effect is the tendency for those who are successful to become more successful and those who struggle to struggle more.  This is a serious problem for struggling readers.  When students struggle to read, they read less than their peers who are not struggling.  They also can't read many of the kinds of books that would give them access to a lot of the vocabulary and complex language that they will need to read the increasingly complex books that they will see throughout their school career and adult life.  As a result, their vocabularies grow more slowly than proficient readers, they know less about the world because they have read less, and they have less understanding of complex language.  This, in turn, makes them worse readers.  Left unchecked, the gap will only continue to grow because while struggling readers continue to learn how to read, proficient readers are already reading to learn, and the more we read to learn the better we tend to get at reading. This is why reading aloud to struggling readers and providing them with accommodations for longer writing assignments is so critical.  It stops a manageable problem from cascading into a catastrophe.