Nonmainstream dialect use and specific language impairment.

Most work looking at specific language impairment (SLI) has been done in the context of mainstream dialects. This paper extends the study of SLI to two nonmainstream dialects: a rural version of Southern African American English (SAAE) and a rural version of Southern White English (SWE). Data were language samples from 93 4- to 6-year-olds who lived in southeastern Louisiana. Forty were classified as speakers of SAAE, and 53 were classified as speakers of SWE. A third were previously diagnosed as SLI; the others served as either age-matched (6N) or language-matched (4N) controls. The two dialects differed in frequency of usage on 14 of the 35 coded morphosyntactic surface patterns; speakers of these dialects could be successfully discriminated (94%) from each other in a discriminant analysis using just four of these patterns. Across dialects, four patterns resulted in main effects that were related to diagnostic condition (SLI vs. 6N), and a slightly different set of four patterns showed effects that were related to developmental processes (4N vs. 6N). More interestingly, the surface characteristics of SLI were found to manifest in the two dialects in different ways. A discriminant function based solely on SAAE speakers tended to misclassify SWE children with SLI as having normal language, and a discriminant function based on SWE speakers tended to misclassify SAAE unaffected children as SLI. Patterns within the SLI profile that cut across the two dialects included difficulties with tense marking and question formation. The results provide important direction for future studies and argue for the inclusion of contrastive as well as noncontrastive features of dialects within SLI research.