Beyond Words: Natural Language Sampling of Lexical and Non-Word Vocalizations in Preschool Children with Autism, Down Syndrome, and Fragile X Syndrome

The study examined whether natural language sampling measures based on words and non-words complement standardized language tests in characterizing expressive communication in 82 preschool children with autism and language impairment, Down syndrome, and Fragile X syndrome. Researchers collected 10-minute natural speech samples during standardized play and measured lexical diversity, intelligibility, word approximations, and various types of non-word vocalizations. The groups did not significantly differ on standardized expressive language tests, but children with Fragile X syndrome showed better performance on some word-based measures. Non-word vocalizations primarily revealed differences within groups. Word-based measures were consistently associated with standardized language skills, while non-word vocalization associations varied by type. The research identified three communication profiles: higher language, lower output, and high output with low structure. Standardized tests and natural language sampling provide complementary information about expressive communication in children with developmental disorders.