Predicting Expressive Vocabulary Acquisition in Children With Intellectual Disabilities: A 2-Year Longitudinal Study PurposeThis study’s objectives were to describe expressive vocabulary acquisition in children with intellectual disabilities (ID) and to examine specific pre- and early linguistic behaviors used to request and comment, chronological age, cognitive skills, and vocabulary comprehension as predictors of expressive vocabulary.MethodThis study included 36 children with ID, age 3;00 (years;months) ... Article
Article  |   December 01, 2010
Predicting Expressive Vocabulary Acquisition in Children With Intellectual Disabilities: A 2-Year Longitudinal Study
 
Author Affiliations & Notes
  • Joke Vandereet
    Experimental Otorhinolaryngology, Katholieke Universiteit, Leuven, Belgium
  • Bea Maes
    Centre for Parenting, Child Welfare, and Disabilities, Katholieke Universiteit Leuven
  • Dirk Lembrechts
    MODEM, Communication and Computer Centre, Antwerp, Belgium
  • Inge Zink
    Experimental Otorhinolaryngology, Katholieke Universiteit Leuven
  • Contact author: Joke Vandereet, Katholieke Universiteit Leuven, Experimental Otorhinolaryngology, Department of Neurosciences, Herestraat 49 bus 721, 3000, Leuven, Belgium. E-mail: joke.vandereet@med.kuleuven.be.
Article Information
Development / Research Issues, Methods & Evidence-Based Practice / Speech, Voice & Prosody / Language
Article   |   December 01, 2010
Predicting Expressive Vocabulary Acquisition in Children With Intellectual Disabilities: A 2-Year Longitudinal Study
Journal of Speech, Language, and Hearing Research, December 2010, Vol. 53, 1673-1686. doi:10.1044/1092-4388(2010/09-0187)
History: Received August 27, 2009 , Revised January 24, 2010 , Accepted April 2, 2010
 
Journal of Speech, Language, and Hearing Research, December 2010, Vol. 53, 1673-1686. doi:10.1044/1092-4388(2010/09-0187)
History: Received August 27, 2009; Revised January 24, 2010; Accepted April 2, 2010
Web of Science® Times Cited: 3

PurposeThis study’s objectives were to describe expressive vocabulary acquisition in children with intellectual disabilities (ID) and to examine specific pre- and early linguistic behaviors used to request and comment, chronological age, cognitive skills, and vocabulary comprehension as predictors of expressive vocabulary.

MethodThis study included 36 children with ID, age 3;00 (years;months) to 6;05, with an average initial expressive vocabulary of 67 words. Expressive vocabulary acquisition was longitudinally followed over a 2-year period based on 4-monthly administrations of the Dutch version of the MacArthur Communicative Development Inventory/Words and Gestures (I. Zink & M. Lejaegere, 2002). Specific pre- and early linguistic behaviors used to request and comment as well as cognitive skills and vocabulary comprehension were measured at baseline.

ResultsIndividual growth modeling indicated that vocabulary comprehension was the only unique predictor of initial expressive vocabulary. Subsequent vocabulary growth was uniquely predicted by proportion of bimodal gesture + vocalization comments, chronological age, and cognitive skills.

ConclusionsThe results of this study underscore the great heterogeneity in expressive vocabulary skills in children with ID. The importance of prelinguistic communication, chronological age, cognitive skills, and vocabulary comprehension for explaining differences in expressive vocabulary skills is discussed.

Acknowledgments
The research in this article was supported by a grant from the Marguerite-Marie-Delacroix support fund to the first author. We also thank Beta, Brabantse Dienst voor Thuisbegeleiding, Cera, Hulpmiddelencentrale, and the Lions Club Kortenberg for their support. Special thanks to the children, parents, and speech-language pathologists who participated in this study.
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