What you should know.

Types of Dyslexia

Dyslexia can cause deficits in two major areas associated with reading: sight word recall and retention, and phonological processing.  Often dyslexics experience significant difficulties in one of these areas, yet little to no difficulties in the other. However, a diagnosis of one type of dyslexia does not mean that the other type of dyslexia is not present, simply that it is not severe enough to clinically diagnosis.  This is why DIA chooses to diagnosis dyslexia using the Boder Classification System.

Boder Classification System for Dyslexia

DECODING:  Involves either sight recognition of words which are phonetically irregular such as “should, enough, etc…” or phonetic decoding where words are read by breaking them down into units or syllables.  Both of these decoding processes are needed to read or decode words.

ENCODING: Ability to spell words.  Words are spelled two ways:

(A) Spelling by sight or visualizing the word as a whole

(B) Spelling by sound or breaking the word down into its sound parts or phonemes.

Dyseidetic Dyslexia

If a child can’t read (decode) and/or spell (encode) because he or she is unable to remember whole, irregular sight words (also known as eidetic words) this condition is known as Dyseidetic Dyslexia.

Dysphonetic Dyslexia

If a child can’t read (decode) and/or spell (encode) because he or she is unable to break phonetically regular words (also known as phonetic words) down into their sound parts, this condition is known as Dysphonetic Dyslexia.

 Dysphoneidetic Dyslexia

If a child can’t read (decode) and spell (encode) words either eidetically or phonetically, this is known as Mixed Dyslexia or Dysphoneidetic Dyslexia.  This is the severest form of dyslexia because it involves both types of coding functions.

There is strong evidence that at least one type of dyslexia, Dyseidetic Dyslexia, is genetic, and that it is passed down to each generation in varying degrees regardless of the sex of the child.

Dysphonetic Dyslexia appears to be polygenic.  That is, there is not a clear-cut genetic influence.  There is however some evidence that this type of dyslexia may be linked to chronic otitis media (regularly occurring ear infections) before the end of the second year of the child’s life.