Understanding the Visual Nature of Dyslexia and Reading/Attention Problems


Thanks to our colleague, Dr. Carl Hillier, I was reminded of a phenomenal article in the journal Trends in Cognitive Sciences last year by Vidyasagar and Pammer:  DYSLEXIA – Visuo-Spatial Attention Deficit – Trends Cog Sci 09

There are excellent diagrams in the article showing why dyslexia represents a deficit in visuo-spatial attention and not in phonological processing, and the authors’ synopsis is very powerful.  They write:

Developmental dyslexia affects up to 10 per cent of the population and it is important to understand its causes.  It is widely assumed that phonological deficits, that is, deficits in how words are sounded out, cause the reading difficulties in dyslexia.  However, there is emerging evidence that phonological problems and the reading impairment both arise from poor visual (i.e. orthographic) coding.  We argue that attentional mechanisms controlled by the dorsal visual stream help in serial scanning of letters and any deficits in this process will cause a cascade of effects, including impairments in visual processing of graphemes, their translation into phonemes and the development of phonemic awareness.  This view of dyslexia localizes the core deficit within the visual system and paves the way for new strategies for early diagnosis and treatment.”

That prompted me to think about why ophthalmologists and educators give parents such a hard time when they try to talk to them about the contribution of vision problems to reading problems.  We can track the source of confusion and misinformation to papers such as the one by the Shaywtiz spousal research team at Yale:  DYSLEXIA – SHAYWITZ SWIPE AT VT- JAAPOS 03

The Shaywitzes write:   “People with dyslexia and their families frequently consult their physicians about unconventional approaches to the remediation of reading difficulties; in general, no credible data exist to support the claims made for these treatment (eg optometric visual training, medication for vestibular dysfunction, chiropractic manipulation, and dietary supplementation).”

The Shaywitz article appeared in the Journal of the American Academy of Pediatric Ophthalmology (JAAPOS) in 2003.  Not coincidentally, this is the journal of the organization that spearheads the Joint Policy Statement by medical organizations that misinforms the public about vision therapy through straw man arguments lumping it with unproven therapies.  The illogic of the Shaywitz argument is evident in the following diagram:

 

 

What the Shaywitzes are showing is that the occipito-temporal system appears to predominate when a reader has become skilled, and binds together the orthographic, phonological, and semantic features of the word.  This system is toward the rear or posterior part of the brain and involves the visual cortex.  In the JAAPOS article they write:  “The anterior sites, which are critical in articulation, may help the child with dyslexia develop an awareness of the sound structure of the word by subvocalizing, i.e. by forming the word with the lips, tongue, and vocal apparatus, thus allowing the child to read, albeit more slowly and less efficiently than if the fast occipito-temporal  word identification system were functioning.”

So there you have it!  Vision therapy is only “unconventional” if one doesn’t grasp the significance of being able to boost the performance of the visual brain through vision therapy.  In essence, the Shaywitzes, JAAPOS, and physicians in general disregard the role of vision by ignoring the compelling evidence such as Vidyasagar and Pammer review in their paper.

Phonology has a role in the learning to read process.  But when it comes to reading to learn, as Vidyasagar and Pammer argue compellingly, discounting the role of vision is phony-logical.  It is time for educators and physicians to stop paying lip service to helping children with visual dyslexia and visual attention problems through the phonology bypass, and encourage assessments and interventions that boost the occipital or visual parts of the brain.  There are encouraging signs that this has already begun.

3 thoughts on “Understanding the Visual Nature of Dyslexia and Reading/Attention Problems

  1. In working with adults with vision and reading problems, I have found that they 1)say the word to themselves, 2)listen to what they are saying, and 3 translate what they heard. This is a slow, laborious process, a process which is generally unnecesary after vision therapy. Perhaps the heavily phonetic-based reading programs work because they help to bypass the visual deficit. Would a more conventional reading program work after a child was visually ready to read? My clinical experience suggests yes. After therapy, these children respond well to a standard Sylvan Learning center program. Quite obviously a vision therapy program would NOT teach a child to read. Reading instruction would be necessary. The real question is, down the line, after the therapies and reading instruction are complete, who is best able to get information off the page, and who most enjoys reading? Studies in this area would be helpful.

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