A meta-analysis of the association between vocalizations and expressive language in children with autism spectrum disorder.
Jena McDaniel, Kathryn D'Ambrose Slaboch, Paul Yoder
PMID 29195157WHAT IT FOUND
Vocalizations strongly correlate with expressive language in children with autism.
Concurrent measures showed a stronger link than longitudinal ones. This supports assessing prelinguistic vocalizations to predict language outcomes.
Key findings
01The overall association between vocalizations and expressive language is strong, with a weighted mean effect size of r = .50.
02Concurrent correlations were significantly stronger (r = .77) than longitudinal correlations (r = .33).
03Vocalization measures accounted for 25% of the variance in expressive language.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
Only nine studies met inclusion criteria, limiting the generalizability and statistical power for moderator analyses. Many studies did not explicitly define vocalizations, leading to ambiguity in what was measured. Nearly half of the included reports shared participants with other reports, increasing the risk of sample-specific results. The analysis could not determine causality, only association.
The easy way to misread this
Do not assume vocalizations cause language development. The study reports associations, not causal effects. Concurrent correlations are stronger than longitudinal ones, so a high correlation at one time point does not guarantee future language gains.