The acquisition of tense morphology over time by English second language children with specific language impairment: Testing the cumulative effects hypothesis

The cumulative effects hypothesis (CEH) claims that bilingual development would be a challenge for children with specific language impairment (SLI). To date, research on second language (L2) children with SLI has been limited mainly to their early years of L2 exposure; however, examining the long-term outcomes of L2 children with SLI is essential for testing the CEH. Accordingly, the present study examined production and grammaticality judgments of English tense morphology from matched groups of L2 children with SLI and L2 children with typical development (TD) for 3 years, from ages 8 to 10 with 4-6 years of exposure to English. This study found that the longitudinal acquisition profile of the L2 children with SLI and TD was similar to the acquisition profile reported for monolinguals with SLI and TD. Furthermore, L2-SLI children's accuracy with tense morphology was similar to that of their monolingual age peers with SLI at the end of the study, and exceeded that of younger monolingual peers with SLI whose age matched the L2 children's length of exposure to English. These findings are not consistent with the CEH, but instead show that morphological acquisition parallel to monolinguals with SLI is possible for L2 children with SLI.