Speed of processing, working memory, and language impairment in children.
OBJECTIVE
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.


METHODS
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.
Leonard
Laurence B
LB
Speech, Language, and Hearing Sciences, 500 Oval Drive, Heavilon Hall, Purdue University, West Lafeyette, IN 47907, USA. xdxl@purdue.edu
Ellis Weismer
Susan
S
Miller
Carol A
CA
Francis
David J
DJ
Tomblin
J Bruce
JB
Kail
Robert V
RV
D000293:Adolescent; D002648:Child; D003072:Cognition Disorders / Q000175:diagnosis / Q000453:epidemiology; D005260:Female; D006801:Humans; D007806:Language Disorders / Q000175:diagnosis* / Q000453:epidemiology; D008297:Male; D008403:Mass Screening / Q000379:methods; D008569:Memory Disorders / Q000175:diagnosis* / Q000453:epidemiology; D008570:Memory, Short-Term; D009633:Nonverbal Communication; D011930:Reaction Time; D012720:Severity of Illness Index; D013067:Speech Perception; D014705:Verbal Behavior