The geometric preference subtype in ASD: identifying a consistent, early-emerging phenomenon through eye tracking.
Adrienne Moore, Madeline Wozniak, Andrew Yousef and 4 others
PMID 29581878WHAT IT FOUND
Toddlers with ASD looked more at geometric patterns than at social scenes.
Those who strongly preferred patterns had more severe autism scores and lower receptive language. Eye tracking identified 18% of toddlers with ASD in this sample.
Key findings
01Toddlers with ASD averaged 48.4% of fixation time on geometric images, compared with 31.2% for typically developing toddlers, 28.6% for toddlers with developmental delay, and 30.0% for toddlers with other diagnoses, and this group difference was significant.
02Among toddlers with ASD, those with more than 69% geometric looking had ADOS social-affect scores of 16.7 and total scores of 20.9, compared with ADOS social-affect scores of 11.4 and total scores of 14.5 for those with more than 69% social looking.
03At the 69% geometric-looking cut-off, 18% of toddlers with ASD had a positive result, and 97% of toddlers without ASD had a negative result among the 227 analyzed.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study did not test an intervention. It describes an eye-tracking pattern, not a treatment effect. The test found only 18% of toddlers with ASD at the 69% cut-off in the 227 analyzed. Positive and negative predictive values were calculated using a 1/3 ASD rate in this referral sample, not the 1/68 general population rate, so they may not match a typical clinic or community population. The sample came from a specialty autism evaluation center, and many children were referred for developmental concerns, so results may not generalize to all toddlers. The authors' own earlier work defined the effect and the cut-off, and this is a conceptual replication by the same group. The authors state that differences in low-level visual salience, attentional disengagement, or aversion to social stimuli could explain the geometric-looking pattern, not social preference alone. Forty-three of 270 enrolled toddlers were excluded for reasons such as vision abnormality, tantrum, or too little usable eye-tracking data. Seventeen percent of the sample received a diagnostic group assignment based on an evaluation between 18 and 30 months rather than at 30 months or older.
Declared interests
The study was funded by the National Institute of Mental Health. The supplied text does not report commercial funding or author conflict-of-interest disclosures.
The easy way to misread this
Do not read the 97% specificity as evidence that this eye-tracking test can diagnose autism in a clinic. At the 69% geometric-looking cut-off, it identified only 18% of toddlers with ASD in the 227 analyzed, and the predictive values were calculated using a 1/3 ASD rate in this referral sample rather than a general population rate.