The impact of individual factors on linguistic alignment of autistic boys and their mothers.

Linguistic alignment reflects shared linguistic behaviors (e.g. syntax and lexicon) between interlocutors. Recent work has examined whether autistic children align to the same degree as their non-autistic peers, with current findings inconclusive. This study took an in-depth approach to investigating factors contributing to variation in linguistic alignment among autistic individuals. Eighteen school-age and adolescent autistic male participants, 14 males with fragile X syndrome + autism, and their mothers participated in the study. Dyads engaged in an unstructured conversation for ~12 min. Using Bayesian linear mixed-effect models, we assessed the relationships between alignment and within-individual factors of the participants. Lexical and syntactic alignment were uniquely influenced by within-participant factors. Maternal lexical and syntactic alignment were differentially associated with participant cognitive and expressive language abilities, and according to etiology (fragile X syndrome + autism vs idiopathic autism). This study highlights the complexity of alignment in autistic individuals and their mothers. Results suggest that alignment is a dynamic process that is motivated in part by within-individual traits of their children. Consequently, characterizing alignment in autism requires a highly nuanced and thoughtful approach that accounts for the heterogeneity of the population.