Dyslexia affects sound too

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Health & Medical News - Dyslexia affects sound too - 17/11/2003

 

http://www.abc.net.au/science/news/health/HealthRepublish_986722.htm]

 

Dyslexia affects sound tooHeather Catchpole

ABC Science Online

 

Monday, 17 November 2003

 

 

 

 

Dyslexia is about how the brain processes sight and sound together, not just

about having problems reading, say U.S. researchers.

 

Dr Mark Wallace and colleagues from the Wake Forest University Baptist Medical

Center presented their new findings at a recent Society for Neuroscience meeting

in New Orleans.

 

They discovered that people with dyslexia find it difficult to distinguish

sights and sounds that occur quickly one after the other.

 

" For the first time, there is evidence that dyslexia is a multi-sensory

disorder, " said Wallace. " It isn't solely a problem with visual processing or

with language. This is a novel way of looking at the disorder.

 

" Until now, experts have thought that dyslexia was either a visual processing

problem or a problem involving language areas of the brain. But our study

suggests that it's actually a problem combining visual information with auditory

information. "

 

The researchers looked at 36 people with dyslexia and 29 without dyslexia, then

studied how they responded to two lights flashing. People in the study had to

tell whether the light on the left or right flashed first. A loud sound just

before the flashes also helped to discriminate between the lights.

 

Sounds made more than 150 milliseconds before the flashes benefited all the

people in the study. But sounds made up to 350 milliseconds before the flashes

only helped those with dyslexia.

 

The researchers said that this provided evidence that the brain blurred things

that happened in quick succession, and that in people with dyslexia this

blurring happened over longer periods of time.

 

" Dyslexics were getting an advantage from sounds that were too long ago for

people without dyslexia, " Dr Tim Bates, from Australia's Macquarie Centre for

Cognitive Science told ABC Science Online.

 

Dr Anne Castles, from Australia's University of Melbourne, said the results held

a lot of promise.

 

" There's been research on how people with dyslexia have trouble processing rapid

visual information and comparable auditory problems, " said Castles. " They've put

those together and said the problem is to do with integrating both sight and

sound. The good thing about it is that they've then linked that to how a child

might be trying to learn to read. "

 

Wallace's colleague Dr Lyn Flowers suggested that the study could be developed

as a test for early diagnosis of dyslexia.

 

" The study did not use letters and speech sounds, suggesting that there may be a

very basic sensory integration deficit in dyslexia that underlies reading

difficulties, " Flowers said.

 

Bates and Castles disagreed.

 

" There's no evidence for it having implications for early diagnosis, " said

Bates. " What may be true for some people with dyslexia, is probably not true for

all people. "

 

Castles added that more work would be needed to see if the research could be

applied to all people with dyslexia, and warns that there may be other factors

that account for dyslexia.

 

" We don't want to be thinking of developing diagnostic tests; we want to be

thinking about detecting any of a whole range of problems a child might have

during the learning process. Dyslexia is a heterogenous disorder and it's

extremely unlikely you have a solution for every child. "

Related StoriesFinding the seeds of dyslexia in newborns, News in Science 19 Aug

1999

Brains different dyslexic are, News in Science 5 Oct 1999

 

 

 

© 2003 Australian Broadcasting Corporation

 

 

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