Amplitude envelope onsets and developmental dyslexia: A new hypothesis
- Usha Goswami*,†,
- Jennifer Thomson*,
- Ulla Richardson*,
- Rhona Stainthorp‡,
- Diana Hughes§,
- Stuart Rosen¶, and
- Sophie K. Scott∥
- *Institute of Child Health, University College London, London WC1N 1EH, United Kingdom; ‡Institute of Education, University of London, London WC1H 0AA, United Kingdom;§ Department of Psychology, Royal Holloway and Bedford New College, University of London, Egham, Surrey TW20 0EX, United Kingdom; and Departments of ¶Phonetics and Linguistics and∥ Psychology, University College London, London WC1E 6BT, United Kingdom
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Communicated by James L. McClelland, Carnegie Mellon University, Pittsburgh, PA (received for review January 25, 2002)
Abstract
A core difficulty in developmental dyslexia is the accurate specification and neural representation of speech. We argue that a likely perceptual cause of this difficulty is a deficit in the perceptual experience of rhythmic timing. Speech rhythm is one of the earliest cues used by infants to discriminate syllables and is determined principally by the acoustic structure of amplitude modulation at relatively low rates in the signal. We show significant differences between dyslexic and normally reading children, and between young early readers and normal developers, in amplitude envelope onset detection. We further show that individual differences in sensitivity to the shape of amplitude modulation account for 25% of the variance in reading and spelling acquisition even after controlling for individual differences in age, nonverbal IQ, and vocabulary. A possible causal explanation dependent on perceptual-center detection and the onset-rime representation of syllables is discussed.
Footnotes
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↵ † To whom reprint requests should be addressed at: Institute of Child Health, 30 Guilford Street, London WC1N 1EH, United Kingdom. E-mail: u.goswami{at}ich.ucl.ac.uk.
- Abbreviations:
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AM, amplitude modulation
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RAN, rapid automatized naming
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PSTM, phonological short-term memory
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RFD, rapid-frequency discrimination
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TOJ, temporal order judgement
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CA, chronological age
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RL, reading level
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WISC, Wechsler Intelligence Scale for Children
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P center, perceptual center
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- Copyright © 2002, The National Academy of Sciences
