Effects of a Contingent Responses Intervention on the Quantity and Quality of Vocalizations of Preschool Children with Autism Spectrum Disorder.

McDaniel (2025) tracked preschool boys with fragile X syndrome. The team asked: which early skills forecast later word variety?

They tested consonant inventory, autism severity, and intentional communication. Then they waited and counted new words.

Kids who knew more consonant sounds at the start had richer vocabularies later. Higher autism severity also predicted fewer new words.

Surprise: intentional communication did not predict word growth. Knowing sounds and autism traits mattered more than pointing or showing.

Leigh et al. (2015) saw the same link between early consonants and later talk in non-verbal preschoolers with autism. Their data set the stage for this finding.

Song et al. (2022) found the opposite: only baseline expressive language, not consonants or autism traits, predicted growth. The difference may be language (Cantonese vs English) or how skills were measured.

Plant et al. (2007) showed older, minimally verbal kids with bigger sound inventories made the fastest speech gains after therapy. Jena extends this pattern down to fragile X preschoolers.

If a preschool client can imitate only three consonants, focus on expanding that sound set before pushing long sentences. Use mirror play, fun mouth toys, and massed trials of new consonants. Track autism severity too—kids with higher traits may need more repetition and visual supports. Skip waiting for perfect joint attention; build sounds first.