Phonological Working Memory and Bilingual Experience Shape Syntactic Comprehension in Autistic Children: A Cross-Linguistic Study

Abstract

This study investigates how monolingual and bilingual autistic children comprehend subject relative clauses (SRCs) and object relative clauses (ORCs) across two languages: French and German. It examines how phonological working memory (PWM), bilingual experience, and test language influence relative clause comprehension. Fifty-five autistic children (25 monolinguals, 30 bilinguals), aged between 4 and 12 years, were tested using a nonword repetition task indexing PWM, which has been previously linked to syntactic ability in autism. Three research questions were investigated: (a) whether clause type and test language affect comprehension accuracy across language groups; (b) whether PWM contributes differently to SRC versus ORC comprehension in monolingual and bilingual children; and (c) whether individual variation in bilingual exposure, quantified as cumulative exposure, modulates PWM’s contribution to syntactic processing. We adopted both between-group comparisons (monolingual vs. bilingual) and within-group analyses of bilingual variability. Generalized linear mixed-effects models were employed to assess group differences in accuracy, while linear mixed-effects models examined bilingual variation. Each research question was modeled separately, including fixed effects, interactions, and random intercepts. Age and socioeconomic status were covariates. Results showed that ORCs were consistently more challenging than SRCs across languages. Higher PWM predicted better accuracy in both languages. Monolinguals relied more on PWM for SRCs, while bilinguals showed a more uniform PWM effect across clause types. Notably, cumulative exposure to the test language contributed to higher ORC accuracy. These findings underscore how PWM and bilingual experience jointly shape syntactic processing in autism, highlighting the value of moving beyond categorical group comparisons. They also provide compelling evidence that bilingualism does not hinder syntactic comprehension in autism, reinforcing the recommendation to support bilingual input in autistic children.