Response to changing contingencies in infants at high and low risk for autism spectrum disorder.
Jessie B Northrup, Klaus Libertus, Jana M Iverson
PMID 28301087WHAT IT FOUND
At 10 months, high-risk infants shook a silent rattle less at first than low-risk infants, showing weaker expectation that shaking will make sound.
They learned the sounding-rattle contingency at a similar rate, so this is not a simple learning deficit.
Key findings
01At 10 months, low-risk infants had a higher proportion of initial shaking with the first sounding rattle than high-risk infants without ASD (p < .001) and infants later diagnosed with ASD (p = .001).
02For high-risk infants, more shaking in the first 10 seconds with the silent rattle at 10 months predicted higher later cognitive scores, explaining 22% of variability.
03At 6 months, all 9 infants later diagnosed with ASD had no initial shaking of the first rattle, compared with 47% of low-risk and 73% of high-risk infants without ASD.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The ASD group was small: 9 infants, so the 6-month finding should not be treated as a stable pattern. Some high-risk infants had missing Mullen scores at 18, 24, or 36 months, and one was excluded from the cognitive prediction analysis. The study did not find significant differences between infants later diagnosed with ASD and high-risk infants without ASD in initial response to the rattles. The extinction burst measure did not relate to later ASD severity. The task involved objects only, not social interaction. The authors describe the protocol as a possible future measure of risk only if replicated. High-risk infants without ASD unexpectedly decreased shaking with the second sounding rattle, and the paper does not explain this.
The easy way to misread this
Do not use this rattle task to diagnose ASD or to predict which high-risk infant will receive a diagnosis. The study found group differences, but it did not find significant differences between infants later diagnosed with ASD and high-risk infants without ASD in initial response, and the silent-rattle measure did not predict ASD severity.