A Physiological Marker of Recognition Memory in Adults with Autism Spectrum Disorder? - The Pupil Old/New Effect.
Pupil size gives a silent, non-verbal read-out of recognition memory, and it stays flat in autistic adults.
01Research in Context
What this study did
Ring et al. (2020) asked adults with and without autism to look at pictures.
Some pictures were new, some they had seen minutes earlier.
A camera tracked how wide their pupils got with each image.
What they found
Typical adults’ pupils grew bigger for new pictures than for old ones.
Adults with autism did not show this pupil old/new effect.
They also scored lower on the memory test overall.
How this fits with other research
Massand et al. (2013) saw the same low scores, but brain waves still showed a tiny late response.
The pupil study extends that work: the memory gap starts even earlier, at the brain-stem level.
Bradford et al. (2018) and Fan et al. (2009) found sluggish pupil reflexes to light in autistic teens and kids.
Together the papers line up a chain: basic pupil control is off, so memory-linked dilation never kicks in.
Why it matters
If a client can’t say what they remember, watch their pupils while you show known and new items.
No change in size means the item is not coded as familiar.
Use this silent probe to gauge learning in low-verbal adults and to adjust teaching trials on the spot.
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02At a glance
03Original abstract
This study investigated the pupil Old/New effect in individuals with Autism Spectrum Disorder (ASD) and typical development (TD). Participants studied verbal and visual meaningful and meaningless materials in black and white on a computer screen. Pupil sizes were measured while participants performed a Remember (episodic memory with context)/Know (semantic memory, no context) recognition memory test. ASD compared to TD individuals showed significantly reduced recognition rates for all materials. Both groups showed better memory for visual compared to verbal (picture superiority effect) and meaningful compared to meaningless materials. A pupil size ratio (pupil size for test item divided by baseline) for old (studied) and new (unstudied) materials indicated larger pupils for old compared to new materials only for the TD but not the ASD group. Pupil size in response to old versus new items was positively related to recognition accuracy, confirming that the pupil Old/New effect reflects a memory phenomenon in the ASD group. In addition, this study suggests an involvement of the noradrenergic neurotransmitter system in the abnormal hippocampal functioning in ASD. Implications of these findings, as well as their underlying neurophysiology, will be discussed in relation to current theories of memory in ASD. Autism Res 2020, 13: 627-640. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Most measures of memory in Autism Spectrum Disorder (ASD) depend on verbal answers. In addition to these verbal answers, this study measured the size of the participants' pupil in response to studied and unfamiliar materials revealing memory difficulties in ASD. Measuring pupil size works nonverbally, outside of conscious awareness and forms the basis of studies on less verbal persons with ASD. Mechanisms and brain regions underlying memory differences in ASD are discussed.
Autism research : official journal of the International Society for Autism Research, 2020 · doi:10.1002/aur.2251