The Effect of Bilingualism and Verbal-Memory on Syntactic Abilities of Children with High Functioning Autism

Background: Little is known about the influence of bilingualism and verbal memory on syntactic abilities of children with High Functioning Autism (HFA). Previous studies exploring syntactic abilities of monolingual children with HFA show large variability (e.g., Roberts, Rice, & Tager–Flusberg 2004). Some monolingual children with HFA have intact morphosyntactic abilities (Kjelgaard & Tager-Flusberg 2001, Novogrodsky 2013), while others show impaired syntax (e.g., Durrleman, Marinis & Franck 2016). Similar picture is shown for verbal memory. Some studies report lower verbal memory in children with ASD as compared to peers with Typical Language Development (TLD), others do not confirm this gap (Durrleman et al. 2017; Schaeffer, 2018). Moreover, it is not clear whether syntactic abilities of children with HFA are linked to deficiencies in verbal memory.

Objectives: The current study assessed separate and combined effects of bilingualism and HFA on verbal memory and syntactic abilities of children. Additionally, it explored to what extent syntactic abilities are associated with the capacity of verbal memory in children with HFA and TLD.

Methods: Eighty-seven monolingual Hebrew-speaking and bilingual Russian-Hebrew-speaking children aged 4;6-9;2 participated in the study: 29 children with HFA (17 monolingual and 14 bilingual) and 58 children with TLD (28 monolingual and 30 bilingual). The groups were matched for age and non-verbal IQ. Syntactic abilities were assessed using LITMUS Sentence Repetition tasks-30 (bilingual children were tested in each of their two languages) based on Armon-Lotem and Meir (2016). In both languages, the test includes 30 sentences that represent simple structures (e.g. SVO sentences with obligatory and optional prepositions) and complex structures (e.g. biclausal sentences with coordination and subordination, object wh-questions, relative clause sentences and conditionals). Structures that are specific to one language were included (e.g., subject relatives for Russian; oblique wh-questions for Hebrew). Verbal memory was evaluated based on Forward Digit Span for verbal short-term-memory and Backward Digit Span for verbal working memory.

Results: As a group, children with HFA had lower scores compared to their TLD peers on measures of syntactic abilities and verbal memory. However, some monolingual and bilingual children with HFA showed intact syntactic abilities, while others scored at risk for Language Impairment. The syntactic errors of the children at risk for Language Impairment were like those of children with Developmental Language Disorder. Importantly, syntactic abilities in children with HFA were not associated with their verbal memory skills. Furthermore, no differences in verbal memory were found between children with HFA who were at risk of Language Impairment and children with no risk. Our findings showed that bilingualism similarly affected syntactic abilities of children with TLD and HFA, demonstrating that bilingualism is not an impeding factor for language and cognitive development of children with HFA.

Conclusions: To conclude, our study demonstrates that (1) regardless of languages status (bilingual versus monolingual), children with HFA at risk for Language Impairment exhibit impaired syntax similarly to those reported in the literature for children with Developmental Language Disorder, and (2) syntactic difficulties in children with HFA are not attributed to deficient verbal memory.