Evidence of Reduced Global Processing in Autism Spectrum Disorder.
Rhonda D L Booth, Francesca G E Happé
PMID 26864159WHAT IT FOUND
People with ASD were slower to recognise fragmented pictures and less able to tell possible from impossible figures than matched controls.
The differences were small and inconsistent, so this is lab evidence, not a clinical test.
Key findings
01The ASD group took 24.9 seconds on average to identify fragmented pictures correctly, compared with 23.4 seconds for controls, and this was significantly slower.
02ASD participants were significantly less able to discriminate possible from impossible figures than controls, although the difference was small.
03There was no significant group difference in accuracy for possible or impossible figures, or in response time to either figure type.
STILL TO COME
How it was doneWhat they found
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What it does not show
The sample was small and all participants were male, so the findings may not apply to females with ASD. The reported outcomes were computerised visual recognition and judgement tasks, not measures of everyday functioning. Several important differences were not significant or were small: the frame-number difference was a trend, and the impossible-figures sensitivity difference had a small effect size. Three participants were removed from the impossible-figures analysis, so that task analysed 25 ASD and 28 control participants rather than the full sample. Many IQ scores were estimated with a short-form Wechsler assessment, and ASD participants with comorbid ADHD, ADD, hyperkinetic disorder, or Tourette syndrome were excluded. The two global-processing tasks were only weakly related, and their association was reduced after controlling for IQ, so they may not measure the same underlying ability. The authors state that larger samples are needed to address whether group differences are restricted to, or more pronounced in, low IQ groups.
Declared interests
The only declaration given is that the study was funded by the Medical Research Council (GB).
The easy way to misread this
Do not read these tasks as a clinical test of autism or as proof that every person with ASD has poor global vision. The differences were small and inconsistent, the sample was small and all male, and the tasks were laboratory measures rather than everyday function.