The impact of bilingual exposure on the cognitive abilities of children with autism

Submission note: A thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Clinical Psychology to the School of Psychology and Public Health, College of Science, Health and Engineering, La Trobe University, Bundoora.

Despite the growing global prevalence of both bilingualism and Autism Spectrum Disorders (ASD), there is a paucity of research exploring both phenomena together. Past studies examining issues associated with children with ASD in multi/bilingual families, have indicated that both parents and professionals believe dual-language learning is detrimental to child development. However, this is contrary to findings from six empirical studies published to date that have explored the impact of bilingualism among children with ASD, suggesting that they have comparable language skills and social communication functioning to their monolingually exposed peers. Although study findings have been consistent, further replications of these preliminary data are required, because considerable heterogeneity exists across the study methodologies, which includes varying operationalisation of bilingualism, sample characteristics and approaches to assessing child language skills. Furthermore, these studies have yet to go beyond the two domains of language and social communication. Hence, this thesis sought to contribute to the growing evidence-base on bilingualism and ASD by adopting a multi-measure approach, and to extend investigations into cognitive domains that have not previously been explored: executive function (EF) and Theory of Mind (ToM) skills. A sample of 21 monolingually exposed and 20 bilingually exposed children with ASD, aged between 21 and 85 months, participated in a 2 to 3-hour assessment session with their caregivers. Measures included a range of direct-administered standardised assessments and experimental tasks, and parent-report questionnaires across the domains of language, social communication, EF and ToM skills, as well as observational coding from filmed parent-child interactions. Overall, this sample of bilingually exposed children with ASD had similar EF, but more impaired language, social communication and ToM abilities, compared to their monolingually exposed peers. Factors such as the role of culture require consideration in future studies of bilingualism and ASD, to ensure study outcomes reflect the impact of dual-language exposure and not extraneous influences.