Which aspect of the bilingual experience affects Theory of Mind in autistic and neurotypical children?

Theory of Mind (ToM), the ability to attribute mental states to oneself and others, is often challenging for autistic children. While bilingualism has been shown to enhance ToM in neurotypical children, its effects on autistic children remain poorly understood and parents and carers have expressed concerns about maintaining dual language exposure for their child with autism. Previous research has largely treated bilingualism as a binary construct (monolingual vs. bilingual), overlooking its complexity and multidimensional nature, thereby preventing clear guidelines related to precise bilingual experiences. This study examined the effects of continuous bilingual experiences on daily-life ToM in 435 children (171 autistic, 264 neurotypical) aged 3–12 years. Various language experience characteristics were measured using the Q-BEx questionnaire. ToM was evaluated with the parental Theory of Mind Inventory 2 questionnaire. Principal Component Analysis was used to reduce the characteristics’ predictors to a smaller subset; linear mixed-effects models were used to analyze the relationship between the resulting Principal Components and ToM. Richer second language exposure and greater proficiency in the second-best language led to higher ToM scores in autistic children only. However, balanced language use across contexts predicted lower ToM ratings on a subset of more basic ToM skills, an effect that disappeared when controlling for first language proficiency. These findings suggest that bilingualism may contribute to mitigating social-cognitive challenges in autism, providing potential cognitive and social benefits. • Prior studies on bilingualism’s effect on Theory of Mind (ToM) focus on group comparisons. • Few studies examine bilingualism’s impact on ToM in autistic children and fewer still on ToM in their daily life. • Higher richness of exposure and proficiency in a second language boosts ToM in daily life in autistic children.