Not just two languages: Using variation in language experience to understand how cognitive resources shape syntactic...

Individuals who learn and use two languages come to that experience in many different ways. Recent studies have shown that to understand bilingualism, it is necessary to characterize the variation in experience that continually shapes the use of the two languages. The current investigation explored the consequences of individual differences in cognitive resources for the processing of syntactic information in two groups of speakers. One group were adults learning Spanish and the other were heritage bilinguals with Spanish as the home language. Both groups were proficient speakers of English. We examined the effects of working memory and cognitive control on syntactic processing, measured by an elicited sentence imitation task. The findings revealed both common and distinct contributions of cognitive resources. Working memory predicted Spanish syntactic processing for second language learners but not for heritage speakers. In contrast, working memory predicted English syntactic processing only for heritage speakers, and this effect was modulated by language dominance. The results for Spanish align with expectations, but the English findings suggest that syntactic processing is shaped not only by proficiency, but also by how the two languages are learned and used together. Cognitive control also showed group-specific effects in response to syntactic complexity: heritage speakers with more reactive control strategies showed better Spanish processing as phrase complexity increased, while L2 learners with more proactive control strategies showed better English processing under increased complexity. Together, these results contribute to our understanding of the effects of language experience on cognitive engagement and shed new light on the dynamics that underlie variation in syntactic processing among bilinguals.