Effects of Specific Language Impairment on a Contrastive Dialect Structure: The Case of Infinitival TO Across Various Nonmainstream Dialects of English.

Purpose: Using data from children who spoke various nonmainstream dialects of English and who were classified as either children with specific language impairment (SLI) or typically developing (TD) children, we examined children's marking of infinitival TO by their dialect and clinical status. Method: The data came from 180 kindergartners (91 speakers of African American English, 60 speakers of Southern White English, 29 speakers of +Cajun); 53 were children with SLI, and 127 were TD children. Data included 4,537 infinitival TO contexts extracted from language samples; each was coded as zero or overtly marked and by preceding verb context (i.e., verbs of motion vs. other).
Results: Across dialects, overall rates of zero marking differed by the children's clinical status (SLI > TD), and other verb contexts accounted for this result. Across the TD and SLI groups, dialect variation was evident for verbs of motion contexts, and the effect was stronger for the TD than for the SLI groups, particularly if the TD children's dialects were classified as +Cajun.
Conclusion: Children's marking of infinitival TO can be affected by both their dialect and clinical status. Results support language assessments that include context-specific rate-based measures of infinitival TO and other contrastive structures when they prove useful for understanding the linguistic profile of SLI within a dialect.