A Large-Scale Study on the Relation Between Multilingualism and Social Traits in Adults With and Without Autism...

Autism Spectrum Disorder is a neurodevelopmental condition characterized by persistent difficulties in social interaction and communication alongside restricted, repetitive patterns of behavior, interests, or activities. Emerging evidence suggests that bi/multilingualism may enhance social interaction skills, yet prior research has largely focused on children, relied on small samples, and used oversimplified monolingual-bilingual groupings. The present study examines whether multilingual engagement predicts autism-associated social traits in adults with and without autism diagnoses. Specifically, we investigated whether childhood and/or current multilingual engagement (operationalized as entropy) predicts social interaction, communication, and overall autistic traits, measured via the Comprehensive Autistic Trait Inventory (CATI). Four hundred and fifty-nine adults (of which 132 diagnosed autistic) participated in the study. Analyses revealed that, both in the full sample and in the subsample of individuals with autism diagnoses, greater language entropy was associated with lower CATI scores in social interaction and overall. No relation between language entropy and communication traits was found. Within the autistic subgroup, the associations between current language entropy and both social interaction and overall CATI scores had large effect sizes (ηp ² = 0.14-0.18). These findings show that multilingual engagement is reliably associated with reduced social autistic traits in adulthood.