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Dyslexia is a condition that causes someone to have trouble reading, right? O.K., so what are Visual Dyslexia, Auditory Dyslexia, Phonological Dyslexia and Orthographic Dyslexia? What are these all about? Answer: The meaning of the term 'dyslexia' can depend on who is using it. The terms for various types of dyslexia describe certain very specific symptoms and conditions that pertain to the problem in general. The details are explained, just read on...

If you should become confused reading about dyslexia, don't feel that you are all alone! When you start to research information about dyslexia you read of Visual Dyslexia, Auditory Dyslexia, Phonological Dyslexia and Orthographic Dyslexia. What do all of these mean? What are the differences between one and the others?

There is a lot of confusion in the terminology being used. Let's try to clear up some of the confusion and get a clearer perspective on the different types of dyslexia and on the term 'dyslexia' in general.

First off, you need to understand that there are two different schools of thought about the term 'dyslexia'. This has led to two working definitions and two different ways in which the word "dyslexia" itself is used. These are:

1. Academic: In the 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 then, anyone who has a problem with reading, for whatever reason, has dyslexia.

2. Popular Use: 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.

So much for the general definitions. Now on to dyslexia types.

The first attempt to sub-divide 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.

Surface Dyslexia. The symptoms of Surface Dyslexia relate to mistakes made in areas where the rules of English pronunciation are inconsistent. For example, "bowl" is read as though it rhymed with "howl", and "enough" might be read as though it rhymed with "dough", or vice-versa.

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 before them on the page.

Double-Deficit Dyslexia is the term applied to the condition of individuals who have both dyslexia types: 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 normally takes place.

Many studies have shown that while dyslexics do have weaknesses in their visual and auditory processing, these weaknesses are not to the same degree. One result could 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.

Orthographic Dyslexia is the last of the dyslexia types. 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.

Perhaps the above explanations have helped clarify the terminology being used to describe the dyslexia types and hopefully, made it more understandable.

For additional information about dyslexia and the different types of dyslexia, follow the links below...