The subtyping of dyslexic children proposed by Boder (1971, 1973) have been validated by quantitative neurophysiological techniques at the Gunderson Medical Foundation, LaCrosse, WI. Children were classified as being dysphonetic (auditory-phonetic disabilities), dyseidetic (visual spatial disabilities) or mixed (deficient in both processes). In one study of 21 dyslexic children between 7 and 10 years of age and six controlled children, there were significant differences between the dyslexic subgroups and between the dyslexic and controlled children on three of the six cognitive tasks (frustration level reading, spelling recognition, and drawing a clock). Significant differences occurred in left temporal parietal theta, and this difference occurred in the area of the angular gyrus, presumed to be important in phonetic decoding. This suggested that the reportedly normal phonetic skills of dyseidetic children may not be normal but rather a sign of overuse of a processing strategy associated with inefficiency of right hemisphere visual gestalt abilities. Additional support for an overuse theory in dyseidetic dyslexia came from the behavior of the children during reading tasks. The dyseidetic children audibly decoded many words whereas dysphonetic and mixed dyslexics skipped unknown words or substituted words with the same beginning sound. On a second study involving 33 eight and nine year old dyslexic children and 31 controls, the results of two of seven cognitive tasks confirmed subtype differences. Significant differences in left temporal parietal theta activity in the electroencephalograms of the dyseidetic children suggested that their reading disabilities may be the result of overuse of linguistic abilities rather than deficient visual spatial skills. [1]

COMMENT. A diagnostic screening test for subtypes of reading disability, the Boder Test of Reading Spelling Patterns, is published by the Psychological Corporation, San Antonio, TX. The Boder Test is easily administered and identifies four subtypes of reading disability on the basis of reading and spelling performance. The test is based on the premise that dyslexic readers have characteristic patterns of strengths and weaknesses in two distinct cognitive components of the reading process: The visual gestalt function and the auditory analytic function. The visual gestalt function underlies the ability to develop a sight vocabulary. The auditory analytic function underlies the ability to develop phonic word-analysis skills. These two cognitive functions are basic to the two standard methods of initial reading instruction: The whole word method and the phonics method. The Boder test provides a diagnosis that is meaningful to the educator in the choice of remediation methods. This matching method or neuropsychological approach to reading remediation involves matching the learning strengths with a teaching strategy designed to exploit these strengths. It is favored by Johnson and Mykelbust who recognize two main subtypes of dyslexia, “visual dyslexia and auditory dyslexia” and also by Mattis who identified language, dyscoordination, and visuospatial subtypes. The validation of Boder's neuropsychological approach and classification of dyslexic subtypes is an important advance in the evaluation of reading remediation methods. The Boder method, matching learning strengths to teaching methods, appears to be theoretically sound and much preferred to techniques based on deficit remediation which involve the training or retraining of damaged or dysfunctional areas of the brain. [2]