Different Origin of Auditory and Phonological Processing Problems in Children With Language Impairment Evidence From a Twin Study Research Article
Research Article  |   February 1999
Different Origin of Auditory and Phonological Processing Problems in Children With Language Impairment
 
Author Affiliations & Notes
  • D. V. M. Bishop
    MRC Cognition and Brain Sciences Unit Cambridge, U.K.
  • Sonia J. Bishop
    MRC Cognition and Brain Sciences Unit Cambridge, U.K.
  • Peter Bright
    MRC Cognition and Brain Sciences Unit Cambridge, U.K.
  • Cheryl James
    MRC Cognition and Brain Sciences Unit Cambridge, U.K.
  • Tom Delaney
    Center for Molecular and Behavioral Neuroscience Rutgers University New Brunswick, NJ
  • Paula Tallal
    Center for Molecular and Behavioral Neuroscience Rutgers University New Brunswick, NJ
  • Contact author: D. V. M. Bishop, PhD, Department of Experimental Psychology, University of Oxford, South Parks Road, Oxford, England, OX1 3UD. Email: dorothy.bishop@psy.ox.ac.uk
  • Currently affiliated with the Department of Experimental Psychology, University of Oxford, Oxford, U.K.
    Currently affiliated with the Department of Experimental Psychology, University of Oxford, Oxford, U.K.×
  • Currently affiliated with the Department of Psychology, University of Denver, Denver, CO
    Currently affiliated with the Department of Psychology, University of Denver, Denver, CO×
Article Information
Special Populations / Genetic & Congenital Disorders / Language Disorders / Speech, Voice & Prosody / Language / Research Articles
Research Article   |   February 1999
Different Origin of Auditory and Phonological Processing Problems in Children With Language Impairment
Journal of Speech, Language, and Hearing Research, February 1999, Vol. 42, 155-168. doi:10.1044/jslhr.4201.155
History: Received October 17, 1997 , Accepted April 10, 1998
 
Journal of Speech, Language, and Hearing Research, February 1999, Vol. 42, 155-168. doi:10.1044/jslhr.4201.155
History: Received October 17, 1997; Accepted April 10, 1998

This study investigated the heritability of auditory processing impairment, as assessed by Tallal's Auditory Repetition Test (ART). The sample consisted of 37 same-sex twin pairs who had previously been selected because one or both twins met criteria for language impairment (LI) and 104 same-sex twin pairs in the same age range (7 to 13 years) from the general population. These samples yielded 55 children who met criteria for LI, who were compared with 76 children whose language was normal for their age (LN group). We replicated earlier work showing that group LI is impaired relative to group LN on ART. However, there was no evidence of a heritable influence on ART scores: Correlations between twins and their co-twins were reasonably high for both MZ and DZ twins, suggesting that performance is more influenced by shared environment than genetic factors. Analyses of extreme scores gave a similar picture of nonsignificant group heritability. In contrast, a test of phonological short-term memory, the Children's Nonword Repetition Test (CNRep), gave high estimates of group heritability. In general, CNRep was a better predictor of low language test scores than ART, but ART did make a significant independent contribution in accounting for variance in a test of grammatical understanding.

Acknowledgments
This work was supported in part by award #12-FY95–0030 from the March of Dimes Birth Defects Foundation. Thanks are due to Sandra Stops for assistance with scheduling and data coding and to Dr. Tony Monaco for assistance with zygosity testing. This study would not have been possible without the generous cooperation of education authorities and schools in Hertfordshire and Cambridgeshire. We also extend our warmest thanks to the families of twins who participated.
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