The influence of bilingualism in school-aged children : an examination of language development in neurotypically developing children and in children with ASD

Since bilingualism and multilingualism are the norm rather than the exception, many children, including children with autism spectrum disorder (ASD), live in bilingual or minority-language households. However, little research has examined the language development of school-aged children who have been exposed to two languages since early childhood, and fewer still have examined bilingual school-aged children with ASD. In this thesis, I examine the influence of bilingualism on language development in both school-aged ND children and in their peers with ASD. This objective will be achieved through the three manuscripts making up this thesis.  For the first manuscript, we completed a review of the literature in which we examined the language development of ND bilingual children, of bilingual children with various developmental disorders, and of bilingual children with ASD. This review revealed that, as with neurotypically developing (ND) children, children with ASD can become bilingual speakers, and that bilingualism is not detrimental to their language development. Our review also revealed some of the limits of the existing literature. First, the majority of existing studies had examined bilingual language development in preschool-aged children with and without ASD, but had not examined the language development of these bilingual children once they reached school age. Second, few studies had compared the language abilities of bilingual children with ASD to those of their ND bilingual peers, and at time of publication, none had compared them to those of ND monolingual children. The results from this review lead to two studies examining the influence of bilingualism on language development in school-aged ND children and in children with ASD.  Our review of the literature suggested that language exposure may play an important role in determining bilingual children’s language ability. However, little was known about its influence in school-aged children. Therefore, for the second manuscript, I examined whether there was a relationship between language development and the amount of language exposure that ND simultaneous bilinguals (i.e. children having been exposed to both languages before the age of three years) received in each of their languages (French and English). I found a relationship between lifetime exposure to English and performances on some English-language expressive language measure, but not on receptive language measures. In French, no relationship between the amount of exposure to French and performances on any of the French-language measures was found. These differences in findings could be due to differences in language exposure ranges across both languages but other potential explanations are also discussed. Findings also show that when receiving 20% of their exposure to a language, most children were able to obtain scores within the average range on the language measures. Moreover, children who were exposed to both of their languages on a daily basis often had stronger performances on language measures than children who did not receive daily exposure to both of their languages. I hypothesized that positive transfer and improved metalinguistic abilities more generally may have contributed to improved language learning abilities in children who used both of their languages on a daily basis.  Findings from the literature review also revealed that little was known about the language abilities of bilingual children with ASD once they reached school-age. With that in mind, the third manuscript reports on a pilot study that examined whether three simultaneous bilingual school-aged children with ASD (without a comorbid language disorder or an intellectual disability) could achieve language levels similar to those of their two French-monolingual peers with ASD. I also explored whether these bilingual children with ASD could reach language proficiency levels similar to those of their 19 ND simultaneous bilingual peers, in both of their languages (French and English), and whether they had similar abilities to those of their 12 ND French-monolingual peers. I found that the simultaneous bilingual children with ASD performed similarly on standardized language measures to their two monolingual peers with ASD, in both of their languages. They also had similar performances to those of their ND bilingual peers, as well as to those of their ND monolingual peers.  Overall, these findings reveal that ND school-aged simultaneous bilinguals and their simultaneous bilingual peers with ASD (without a language disorder or intellectual disability) can achieve language proficiency levels similar to those of their monolingual peers, in at least one, if not both of their languages. While bilingual children are not two monolinguals within one child, our findings are similar to previous findings and show that bilingualism does not appear to impede the language development of school-aged ND bilingual children and bilingual children with ASD.

Keyphrases: Bilingualism, School-Age, Neurotypically Developing Children, Autism Spectrum Disorder (ASD), Language Exposure, Language Ability