Sensory traits are associated with global differences in the pupillary light reflex waveform in young adults

Sensory processing traits describe how individuals respond to and regulate everyday sensory input, yet objective physiological markers of these traits remain difficult to establish. The pupillary light reflex has been proposed as a noninvasive window into sensory differences, but findings have been inconsistent, possibly because complex pupil dynamics are often reduced to single summary measures such as peak constriction. Here we analyzed the pupillary light reflex in 39 young adults. Participants completed the Adolescent/Adult Sensory Profile and questionnaires assessing psychological symptoms, and pupil responses were recorded to brief full-field light flashes in four colors. We quantified proportional pupil change over 0-3 s after stimulus onset using an approach that evaluates the entire response waveform rather than a small set of scalar indices. Trait associations appeared mainly as model-based differences in global fitted waveform shape rather than mean-level shifts. Effects were most pronounced for Sensation Avoiding. Waveform-based analyses may help characterize global temporal response profiles associated with sensory traits, although the present findings do not identify reliable divergence at specific time points or underlying mechanisms.