Peer familiarity and lexical diversity in autistic and typically developing preschoolers during free play

Differences in social communication may shape how autistic children use language with different interaction partners. This study examined lexical diversity during free play interactions with a friend and an acquaintance among 50 preschoolers (21 autistic and 29 typically developing). Each child participated in separate play sessions with the two partners. Overall, autistic children produced less lexically diverse language than TD children. TD children also demonstrated greater lexical diversity with friends than with acquaintances, whereas no systematic partner effect emerged for the autistic group. However, individual profiles based on total word production provided a more nuanced picture: most autistic children varied their verbal output across partners, but the direction of this difference was heterogeneous, with some producing more words with a friend and others with an acquaintance. Thus, autistic children's verbal output appeared sensitive to the interaction partner, although not in the relatively consistent direction observed among TD children. Associations between verbal abilities and lexical diversity were found only during interactions with acquaintances. These findings suggest that social context relates to children's language production in different ways across and within diagnostic groups and may inform individualized peer mediated interventions by supporting the selection of interaction partners who facilitate each child's communication, followed by practice across multiple partners to promote flexible language use and generalization.