Rhyme and rhythm offers new approach on dyslexia

Scientists at University College London have challenged accepted thinking by testing rhythmic ability in dyslexic and non-dyslexic children.

Dyslexia involves difficulty in language processing across reading, writing and speech. It is assumed there is an underlying deficit in sound processing responsible for the problem, but there is no consensus about the underlying neurological cause.

The research team now has strong evidence that it is an inability to detect P-centres, determined by changes in amplitude in the signal, which aid in segmenting syllables at the vowel.

Professor Usha Goswami and Dr Sophie Scott at UCL's Institute of Child Health led the research team.

Professor Goswami said: "We already know that dyslexic children find it much more difficult to identify which words rhyme and which do not. This requires identifying the onset of the vowel, for the example the difference between fit and fat. We found that dyslexic children were relatively insensitive to the amplitude-based cues (called P-centres) that signal the onsets of vowels in speech. Furthermore, we found a correlation in children without dyslexia between their ability to track these amplitude changes and their ability to read and write. We found that exceptionally good child readers were exceptionally good at detecting P-centres.

"This new approach is now being studied in ten languages. It could have significant implications for how we detect and treat dyslexia in future.

"P-centres are determined by comparatively long sound cues - of the order of 0.1-0.2 seconds. Our studies suggest that integrating information over relatively long portions of the signal is important for literacy. These are the cues that enable the division of syllables into onsets and rhymes (s-eat, sw-eet, str-eet). Previous research sought the source of the sound-processing deficit in very rapid changes in the signal of around 400th of a second thought to correspond to phonemes. In our work, this was a relatively weak predictor of reading."

Notes to Editors:

Amplitude envelope onsets and developmental dyslexia: a new hypothesis is published in in PNAS July 2002. Copies available from UCL Media Relations.