Reduced Pupil Oscillation During Facial Emotion Judgment in People with Autism Spectrum Disorder.

Sun et al. (2023) watched pupils while the adults with ASD and 32 typical adults judged faces. Each person saw happy, angry, or neutral faces on a screen. An eye-camera tracked tiny pupil wiggles every millisecond.

The team compared two things: how much the pupil constricted and how fast it wiggled (oscillation). All adults had normal vision and IQ.

Adults with ASD showed the same pupil constriction as typical adults. But their pupils wiggled less—about a large share lower oscillation—while they judged emotions.

Less wiggle happened for every emotion, not just one. The drop was biggest in the first half-second after the face appeared.

Kaiser et al. (2022) also used pupillometry in ASD, but in kids. They saw bigger resting pupils yet smaller phasic jumps to sounds. Sai’s adults had normal resting size; the problem was the rapid wiggle during faces. Together the studies map a shift: kids show dampened big jumps, adults show dampened tiny wiggles.

Sasson et al. (2018) found that typical adults with high autism-like traits ignore vocal cues when reading faces. Sai’s finding adds a body cue—pupil wiggle—that is also off, suggesting face-processing trouble shows up in both behavior and physiology.

There is no clash: the "blunted phasic" kids and "reduced oscillation" adults are different age windows and different pupil metrics.

You now have a quick, silent marker: reduced pupil wiggle during emotion tasks. No extra tests, just add pupillometry to your face-emotion drills. If the pupil stays still, the client may be working harder to decode the face—give clearer models, longer wait time, or pair with vocal cues. Track wiggle change after intervention to see if social training reaches the autonomic level.