"For the first time, there is evidence that dyslexia is a multi-sensory disorder," says Mark Wallace, Ph.D., associate professor of neurobiology and anatomy. "It isn't solely a problem with visual processing or with language. This is a novel way of looking at the disorder."
Wallace said the finding could lead to a simple test for early diagnosis even before school age and better methods for teaching people with reading disabilities.
"Until now, experts have thought that dyslexia was either a visual processing problem or a problem involving language areas of the brain," said Wallace. "But our study suggests that it's actually a problem combining visual information with auditory information."
For the study, 36 people with dyslexia and 29 people without the disorder were tested on their ability to tell which of two lights appeared first. The participants sat in front of a video monitor and pushed a button to report their perception. In both dyslexic and non-dyslexic individuals, sounds presented through headphones were found to help performance.
When lights were accompanied by a sound, participants were better at discriminating lights presented very close together in time. For participants without dyslexia, the sound needed to occur within about 150 milliseconds of the light to get such a benefit. Longer intervals failed to help. People with dyslexia, however, showed benefits even with delays as long as 350 milliseconds.
. "In essence, the brain fuses things that happen very close together in time, and for dyslexics, this fusion appears to happen over longer periods of time than in non-dyslexic persons," said Wallace. "We believe this time differenc
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Contact: Karen Richardson or Shannon Koontz
krchrdsn@wfubmc.edu
336-716-4587
Wake Forest University Baptist Medical Center
9-Nov-2003