First off, let’s see if we can clear up some of the confusion and get a clearer perspective on what the word “dyslexia” really means.
It is important to understand that there are two different schools of thought, two different ways in which the word “dyslexia”itself is used. The two different meanings of dyslexia are:
- In the pure academic sense the word “dyslexia” has a literal meaning based on the etymology of the word itself. From its parts, ‘Dys’ means wrong or problematic (for example, as in ‘dysfunctional’) and ‘lexia’, means pertaining to words and letters. So literally, ‘dys’-‘lexia’ refers to problems with words.
In this sense, anyone who has a problem with reading, for whatever reason, has dyslexia.
- There is a wider use and application, used by parents of dyslexics and by dyslexic adults. In the applications sense, dyslexia refers to a range of symptoms that includes problems with reading, writing and spelling plus other problems such as hearing difficulty, poor memory and a lack of physical coordination.
And so, as you can see, the exact meaning of “dyslexia” depends on who is speaking and the context in which the term is being used.
Secondly, let’s look at the different types of dyslexia..
The first attempt to subdivide and describe the different types of dyslexia was made by Marshall and Newcombe in 1973. They set forth the ideas of ‘surface’, ‘phonological’ and ‘double-deficit’ dyslexia.
The symptoms of Surface Dyslexia relate to the mistakes made where the rules of English pronunciation are inconsistent. For example, “bowl” is read as though it rhymed with “howl”, and “pretty” might be read as though it rhymed with “jetty”.
Phonological Dyslexia is a failure to grasp the phonic nature of the English language. Individuals with it have great problems reading new or nonsense words because they do not and cannot grasp the links between the individual sounds or phonemes and letters on the page.
Double-Deficit Dyslexia is the term applied to the condition of individuals who have both Surface Dyslexia and Phonological Dyslexia.
Auditory Dyslexia and Visual Dyslexia both stem from the magnocellular theory of dyslexia. This theory holds that dyslexics have neurological weaknesses in the magnocellular cells of the thalamus area of the brain. This area is where rapid processing of visual and auditory information takes place.
Many studies have shown that dyslexics do have weaknesses in their visual and auditory processing, but not to the same degree. This means that there is a very close relationship and sometime confusion between these two types of dsylexia.
A result can be that a child with poor hearing skills but with average visual skills may be diagnosed as having Auditory Dyslexia, whereas one with poor visual skills but average hearing may be diagnosed as having Visual Dyslexia.
Then finally there is Orthographic Dyslexia. Orthography is the set of symbols or letters that make up a language. In English this is the 26 letters of the alphabet whilst in Japanese or Chinese it covers thousands of different symbols. And so Orthographic Dyslexia relates to problems in identifying and manipulating letters in reading, writing and spelling.