Longitudinal associations across vocabulary modalities in children with autism and typical development.

This was a correlational study, so it cannot show that early expressive vocabulary, caregiver follow-in, or joint engagement caused later receptive vocabulary. The children with autism were selected from a larger study because they were language delayed and initially had very low expressive vocabulary, so the findings may not apply to all children with autism. The groups were matched as groups, not individually, and other unmeasured variables, such as socioeconomic status or nonverbal mental age, could explain the group differences. The analyses did not control for concurrent expressive and receptive vocabulary at both time points or within-modality stability over time. Caregiver follow-in during higher-order joint engagement and early expressive vocabulary were measured at the same visit, so the order of these variables is unclear. The play sample was only 15 minutes, so it does not show how often this engagement occurs during a typical day. Caregiver reports of receptive vocabulary may be less reliable for children with autism because these children may not visibly demonstrate what they understand. For some analyses, three children with autism with the highest receptive vocabulary scores were dropped, which changes the sample used in those comparisons.

The supplied article text does not include a conflicts of interest or funding declaration. The publication types indicate NIH extramural and non-U.S. government research support.

Do not read the caregiver follow-in finding as proof that this interaction improves receptive vocabulary. The study was correlational, the mediator was measured at the same time as early expressive vocabulary, and the autism group was a language-delayed sample, so the result does not establish a treatment effect.