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Language Impairment

其他書名	Morphosyntactic Development and Its Neurological Correlates
出版	University of California, San Diego and San Diego State University, 1998
URL	http://books.google.com.hk/books?id=l0-AZXV6abwC&hl=&source=gbs_api

註釋Language acquisition is a universal phenomenon but a significant number of apparently normal children fail to acquire language on the normal developmental timetable. The goal of this paper is to address the underlying nature of language impairment (knowledge-based versus processing deficit) by assessing whether linguistic performance varies across contexts or over time. In addition, the degree to which neurological status correlates with language impairment is also investigated. Study 1 used a cross-sectional sample of 33 children with language impairment (LI) and 33 normal controls (NC; age 6 to 14 years, tested on even years) who were administered three language production tasks (a standardized test, a naturalistic interview, a narrative) and a comprehensive neurological examination. Study 2 followed a subset of the LI children (n = 14) longitudinally, with a retesting two years later. Language data were coded for the number of propositions, morphological errors and the frequency and diversity of complex syntax. The neurological examination provided a score (ranging from 0 to 24) which reflected the total number of neurological soft signs. The findings most strongly supported a processing deficit as the underlying cause of language impairment, with minimal support for a knowledge-based deficit. Across tasks, the linguistic performances from children with LI became worse as the processing demands increased. Across age, the developmental trajectory for the morphological abilities of children with LI mapped onto the trajectory for NC with nearly all children with LI performing in the normal range by age 12. However, the trajectory for use of complex syntax dissociates from normal with the majority of children with LI remaining impaired even through 16 years of age. Although the children with LI demonstrated significant delay, the quality of their language productions and their errors was not dramatically different than their normal counterparts. With respect to the neurological findings, children with LI demonstrated a greater number of soft signs as compared to NC; however, there was little relationship between neurological status and language abilities. Overall, these findings demonstrate that children with LI suffer from a (possibly remediable) deficit which disproportionately affects language and the results raise questions about the scope of the underlying deficit and the presence of subgroups within the LI population.