Pupil Dilation Progression Modulates Aberrant Social Cognition in Autism Spectrum Disorder.
Autistic teens' pupils follow a distinct path during social scenes, giving you a quick, silent clue about their real-time social attention.
01Research in Context
What this study did
Bast et al. (2019) watched teens' pupils while they judged social scenes. Half the kids had autism, half were neurotypical. The team tracked how fast pupils constricted, how long before they dilated, and how big the dilation grew.
They linked each teen's pupil pattern to how well the teen guessed the emotions in the scenes.
What they found
Autistic teens showed a unique pupil signature: bigger constriction, longer wait, then larger dilation. Their accuracy still rose, but the link between pupil size and accuracy differed from typical peers.
In plain words, the eye told a different story even when the answer was right.
How this fits with other research
Matson et al. (2013) also used eye-tracking in autistic and typical teens. They measured where eyes landed, not pupil size, and found autistic kids looked less at faces yet could still score well on emotion tasks. Nico's pupil data now show the brain may reach the right answer through a separate route.
Byiers et al. (2025) report that autistic kids with ADHD show jumpier, less precise eye movements. Nico's stricter pupil-timing pattern could be another piece of the same sensorimotor difference puzzle.
Congiu et al. (2016) found autistic children could follow gaze but missed its mental meaning. Together these studies suggest gaze behavior is not one problem but many: where we look, how steady the eye is, and how the pupil reacts can each tell a different part of the social-cognition story.
Why it matters
You can spot altered attention gating without a single question. If a teen's pupils show the autism signature during social tasks, slow the pace and add extra prompts; the brain needs more time to gate the input. Pair this cheap biosignal with your standard social-skills program to judge when the client is truly engaged, not just compliant.
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02At a glance
03Original abstract
Progression of pupil dilation (PD) in response to visual stimuli may indicate distinct internal processes. No study has been performed on PD progression during a social cognition task. Here, we describe PD progression during the Movie for the Assessment of Social Cognition (MASC) test in n = 23 adolescents with Autism Spectrum Disorder (ASD) and n = 24 age, IQ and sex-matched neurotypical controls (NTC). The MASC consists of 43 video sequences depicting human social interactions, each followed by a multiple-choice question concerning characters' mental states. PD progression data were extracted by eye tracking and controlled for fixation behavior. Segmenting PD progression during video sequences by principal component analysis, three sequential PD components were unveiled. In ASD compared with NTC, a distinct PD progression was observed with increased constriction amplitude, increased dilation latency, and increased dilation amplitude that correlated with PD progression components. These components predicted social cognition performance. The first and second PD components correlated positively with MASC behavioral performance in ASD but negatively in NTC. These PD components may be interpreted as indicators of sensory-perceptual processing and attention function. In ASD, aberrant sensory-perceptual processing and attention function could contribute to attenuated social cognition performance. This needs to be tested by additional studies combining the respective cognitive tests and the outlined PD progression analysis. Phasic activity of the locus coeruleus-norepinephrine system is discussed as putatively shared underlying mechanism. Autism Res2019. © 2019 The Authors. Autism Research published by International Society for Autism Research published by Wiley Periodicals, Inc. LAY SUMMARY: In adolescents with autism, we found an altered pupil dilation during watching scenes of human interactions. Early pupil dilation correlated positively with the number of correct answers to questions about the shown human interactions. Our findings suggest that aberrant sensory processing and attention function may contribute to altered social cognition in autism.
Autism research : official journal of the International Society for Autism Research, 2019 · doi:10.1002/aur.2178