Experts lambaste French dyslexia study claiming to have found cause, cure
(L-R) Mark Seidenberg, Julian (Joe) Elliott, Jack Fletcher; scientists and experts on how the brain processes language dispute a French study that claimed to have found a cause and possible cure for dyslexia. (Source: UW; UD; UH)
(RNN) - When two French physicists proclaimed last month that they had found a cause and cure for dyslexia the story went viral and cries of outrage soon followed.
A professor from the University of Wisconsin who is a cognitive scientist, neuroscientist and psycholinguist fired the first shot.
“Dyslexics, their families and teachers, reading researchers and treatment specialists, and the organizations that represent them are asking: did someone just discover the cause and cure of dyslexia,” wrote Mark Seidenberg.
“As someone who has conducted research in the area my question is … how did this terrible article get published and how can its harmful impact be counteracted?” said Siedenberg of the University of Wisconsin, where he researches how brain circuits support language and reading.
Guy Ropars and Albert LeFloch said they had discovered a visual cause for dyslexia – a difference in the distribution of a certain kind of receptor in the retina. They said the study could provide an anatomical basis for reading and spelling disabilities. They said they had invented an LED light that corrected the problem.
They studied 30 dyslexics and 30 non-dyslexics. In non-dyslexics they observed a physical difference in the shapes of the area of the eyes that send images to the brain – the images were different, and the brain could choose the one from the dominant eye. But dyslexics see mirror images that cause confusion because the brain can’t decide between them and shifts back and forth. The condition produced letter reversal, among other things.
“It is quite different from the visual models usually discussed,” the researchers responded to Raycom News Network via email. The asymmetry between the distributions of cones in the fovea - a critical area of the retina - and genetics of neural migration are “quite different from a standard relation between vision and dyslexia," they said.
That’s not so, said Seidenberg, who says he has studied language, reading and dyslexia since the disco era. There have been multiple surveys on ocular dominance, which he confirmed with a Google search.
Attacking method, competence of study
Siedenberg’s scathing blog post in Language Logheaped criticism onto the study, claiming it contained a remarkable number of errors, lack of information and poor science.
Several reasons he believes the study is substandard include:
Thirty students in each group is too few to make any kind of conclusion.
Basic information comparing the two groups was not provided – such as handedness, language background, nonverbal IQ measurements, measures of spoken language such as vocabulary comprehension.
There was no testing to determine that the students were actually dyslexic – they were only described as having poorer reading skills than one would expect.
Other experts, authors join in
Jack Fletcher, chair of the Department of Psychology at the University of Houston, echoed Siedenberg’s criticisms.
“This study is like most visual theories of dyslexia – it manufactures a theory of reading to accommodate a visual finding,” he said.
The researchers “confuse associations with causality,” he said.
"Dyslexia is a dysfunction of the brain, not what the eyes do to the brain," he said.
“What they found does not explain the reading problem,” he said. "Further testing would have revealed other differences between dyslexics and non-dyslexics."
Most of the research on connections between image reversals and dyslexia is dated, he said. Much of it dates to the 1970s and 1980s.
Image reversal is not a cause for dyslexia, Fletcher said - and finding research that contradicted their findings should not have been hard to find for the French scientists.
“Relationships between letter reversals and dyslexia has been overwhelmed by the contradictory articles they don’t cite,” he said. “That’s just bad science.”
Joe Elliott of the University of Durham in England is the co-author of “The Dyslexia Debate," which compares past and present research on the subject and compares reading difficulties caused by dyslexia and other learning disabilities.
“The reality is that theories of all kinds are always coming through, but there never seems to be an intervention that is known to work,” Elliott said.
“I have been persuaded several times by vision specialists in the past (whose area is a mystery to most of us), but promises that this is the big explanation for reading difficulty/dyslexia always turn to dust.”
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