Forms of Dyslexia

The Dyslexia Determination Test (DDT) will determine the three fundamental types of dyslexia and its seven permutation patterns. It is used to investigate specific aspects of language problems relating to reading, writing and spelling. The test is in three parts; the first one involves checking for written reversals of numbers and letters. The second part tests the mode of decoding words: eidetic or phonetic. The third and last part consists of assessing whether encoding is eidetic or phonetic.

Examples of the three fundamental types of dyslexia:

Dysnemkinesia (motor)

A deficit in remembering how to do the movements needed for writing.

For example:
      
 The student will make reversals.
       
The student will write b instead of d.

Dysphonesia (auditory)

A deficit in the ability to sound off, to syllabicate, to pronounce and to distinguish sounds of unfamiliar words.
For example:
       
The student reads house instead of home.
       
The student writes aminal instead of animal.

Dyseidesia (visual)

A deficit in the ability to recognize whole words by sight and match them to whole-word sounds.

For example:
      
 The student reads ball instead of bell.
       
The student writes enuf instead of enough.

IMPORTANT: A student with a Non-Verbal Learning Disability and/or a visual acuity problem will not demonstrate characteristics of dyslexia on the DDT.

The above dyslexia tests are available from the Canadian Dyslexia Centre.