Article/Report  |   April 2007
Speed of Processing, Working Memory, and Language Impairment in Children
 
Author Notes
  • Contact author: Laurence B. Leonard, Speech, Language, and Hearing Sciences, 500 Oval Drive, Heavilon Hall, Purdue University, West Lafeyette, IN 47907. E-mail: xdxl@purdue.edu.
Article Information
Language Disorders / Attention, Memory & Executive Functions / Language
Article/Report   |   April 2007
Speed of Processing, Working Memory, and Language Impairment in Children
Journal of Speech, Language, and Hearing Research, April 2007, Vol. 50, 408-428. doi:10.1044/1092-4388(2007/029)
History: Received December 7, 2005 , Revised May 19, 2006 , Accepted June 18, 2006
 
Journal of Speech, Language, and Hearing Research, April 2007, Vol. 50, 408-428. doi:10.1044/1092-4388(2007/029)
History: Received December 7, 2005; Revised May 19, 2006; Accepted June 18, 2006
Web of Science® Times Cited: 135

Purpose: Children with language impairment (LI) often perform below the level of typically developing peers on measures of both processing speed and working memory. This study examined the relationship between these 2 types of measures and attempted to determine whether such measures can account for the LI itself.

Method: Fourteen-year-old children with LI and their typically developing peers participated in a wide range of processing speed and working memory tasks and were administered a comprehensive language test battery. Confirmatory factor analyses were used to compare 3 nested models designed to examine the dimensionality of the speed and working memory measures. A model that included a general speed factor was also evaluated.

Results: The models meeting our evaluation criteria treated speed and working memory as separable factors. Furthermore, nonverbal as well as verbal processing factors emerged from these analyses. Latent variable regression analyses showed that each of the appropriate models accounted for 62% of the variance in the children’s concurrent composite language test scores, with verbal working memory making the largest contribution.

Conclusions: These findings shed light on the relationship among different types of processing and suggest that processing factors can contribute to the understanding of language disorders.

Acknowledgments
This research was supported by Grant P50 DC02746 from the National Institute on Deafness and Other Communication Disorders. We would like to thank the outstanding research team of the Child Language Research Center at the University of Iowa and our investigator colleagues on the grant for their observations during the initial discussions that led to this article. We are grateful to the participants and their families for agreeing to take part in this research endeavor.
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