English Second-Language Input and Vocabulary Development in Bilingual Autistic and Neurotypical Children: To What...

Autistic monolingual children show heterogeneity in their language abilities in the school-age years. School-age bilingual neurotypical children also show heterogeneity in their second-language (L2) abilities as these are modulated by many factors including cumulative L2 input. This study compared school-age neurotypical and autistic children's L2 vocabulary development, as modulated by cumulative L2 input, to determine the extent to which the autistic children formed a distinct group from the neurotypical children.

Participants were autistic (n = 23) and neurotypical (n = 26) bilingual children with English as their L2 and diverse first-language backgrounds, aged 4;7-9;6 (years;months). Children were matched groupwise for age. Children were administered a receptive vocabulary test, and conversational language samples yielded expressive lexical measures: word tokens and types and internal state term tokens and types.

Linear regression modeling revealed that the autistic group had lower scores for all but one vocabulary measure and that higher scores were associated with more L2 input for children in both groups. A hierarchical cluster analysis revealed more nuanced results: One cluster, consisting of all but one of the neurotypical and the majority of the autistic children, overlapped in vocabulary abilities, with the autistic group having somewhat more L2 input. A second cluster consisted of all autistic children except for one neurotypical child and had extensive L2 input and very low vocabulary abilities.

The autistic bilinguals in this study were not a homogeneous group separate from their neurotypical peers. Instead, only some autistic bilinguals showed distinct L2 profiles from their neurotypical peers.