The Linguistic and Cognitive Effects of Bilingualism on Children with Autism Spectrum Disorders

Background: Parents of bilingual children with Autism Spectrum Disorders (ASD) are often advised to talk to their child using only one language to simplify the input they hear (Bird et al., 2012). This stems from the belief that bilingualism may be harmful for language acquisition in children with ASD (Kremer-Sadlik, 2005). Research concerning the language development of bilingual children with ASD is scarce, but the available evidence does not support this claim. That is, bilingual children with ASD do not exhibit additional language delays relative to their monolingual peers with ASD (Hambly & Fombonne, 2012). However, most studies have focused on initial stages of language development using parent report measures. We do not know how bilingualism impacts linguistic abilities at school age, when more complex language should be mastered. Furthermore, no previous study has investigated the effects of bilingualism on executive functions in children with ASD, and whether they may experience a bilingual advantage (Bialystok, 2007).

Objectives: In study 1, we investigated the lexical and morphological abilities of school-age bilingual children with ASD using standardized tests. In study 2, we examined the impact of bilingualism on executive functions (including set-shifting) using direct-testing and parent report of everyday executive functioning abilities.

Methods: Twenty 5- to 9-year-old children with ASD participated in the studies (10 monolinguals and 10 bilinguals) along with 20 typically-developing children. Bilingual status was confirmed by a combination of direct testing and parent report. Participants’ languages included English, French, and Spanish. Children were matched on chronological age and NVIQ. Language skills were assessed using the Peabody Picture Vocabulary Test (Dunn & Dunn, 2007) and the Clinical Evaluation of Language Fundamentals (Semel et al., 2003), or their French/Spanish equivalent. Set-shifting was measured using a computerized version of the Dimensional Change Card Sort Task (DCCS; Zelazo, 2006) along with a measure of executive functioning in daily life (Behavior Rating Inventory of Executive Functioning - BRIEF; Gioia et al., 2000).

Results: LANGUAGE: Although both groups scored in the normal range, there was a significant difference in vocabulary (p = .04), where monolingual children with ASD exhibited higher scores relative to bilingual children with ASD. No significant differences were found on morphological skills (p = .33). DCCS: Bilingual participants with ASD showed better performance relative to their monolingual ASD counterparts (p = .026). BRIEF: The ASD group exhibited poorer set-shifting skills relative to the TYP group (p <.01). However, there where no significant differences related to bilingualism.

Conclusions: Although not presenting delays, bilinguals exhibited lower scores relative to their monolingual peers with ASD on standardized measures of vocabulary, which is likely explained by the relationship between language exposure and language proficiency (Thordardottir, 2011). We provide novel evidence that bilingualism may hold advantages for executive functioning in children with ASD, this was found for the DCCS task but not for parent report of set-shifting in daily life. These findings build on previous research suggesting that bilingualism is not detrimental for the language skills of children with ASD and in fact may provide some advantages.