The role of nonverbal working memory in morphosyntactic processing by school-aged monolingual and bilingual children

•Monolingual and bilingual children completed a Grammaticality Judgment (GJ) task.•Children also completed two non-verbal working memory (WM) measures.•Monolinguals were more sensitive to errors than bilinguals on the GJ task.•Greater WM was associated with GJ performance only in bilinguals.•Nonverbal WM contributes to syntactic processing in children with lower language. The current study examined the relationship between nonverbal working memory and morphosyntactic processing in monolingual native speakers of English and bilingual speakers of English and Spanish. We tested 42 monolingual children and 42 bilingual children between the ages of 8 and 10years matched on age and nonverbal IQ. Children were administered an auditory Grammaticality Judgment task in English to measure morphosyntactic processing and a visual N-Back task and Corsi Blocks task to measure nonverbal working memory capacity. Analyses revealed that monolinguals were more sensitive to English morphosyntactic information than bilinguals, but the groups did not differ in reaction times or response bias. Furthermore, higher nonverbal working memory capacity was associated with greater sensitivity to morphosyntactic violations in bilinguals but not in monolinguals. The findings suggest that nonverbal working memory skills link more tightly to syntactic processing in populations with lower levels of language knowledge.