Native Language and Second Language Convergence and Second Language Instruction Shape Speech-Language Performance in Adult Learners.

We examined native language (L1) and second language (L2) convergence of underlying skills in adult L2 learners as well as the contribution of instructional L2 level on L2 attainment across speech motor, lexical, and narrative levels. Thirty-four adult Spanish L2 learners who had completed at least 1 year of college Spanish participated in this preliminary study. Learners were tested at the speech motor, lexical, and narrative levels in their L1 (English) and L2 (Spanish). L1-L2 convergence was indexed by associative links between corresponding L1 and L2 skills. In regression analyses, the level of Spanish instruction at the time of the study was also considered as a predictor of L2 attainment across speech motor, lexical, and narrative levels. L1-L2 convergence was identified for some speech motor skills (distance, maximum speed) and for lexical skills but was limited for other speech motor skills (duration, spatiotemporal index) and for narrative measures. Furthermore, lexical and narrative measures, but not speech motor measures, showed improvements with Spanish (L2) instruction. L1-L2 convergence and instructional level are predictors of L2 performance in adult language learners. These factors play somewhat different roles across speech motor, lexical, and narrative levels, warranting further "all-system" research across processing and proficiency levels.