Researchers report that different negative emotions produce opposite changes in pupil size: disgust and sadness reliably dilate the pupil, while anger constricts it. The finding appears in Biological Psychology and comes from two laboratory experiments led by Kate McCulloch and colleagues.
The team measured pupil area with infrared eye cameras while participants rated five emotions—happiness, sadness, anger, fear and disgust—after each stimulus. In the first experiment 98 volunteers viewed 36 standardized images and heard 18 short audio clips. Image brightness and contrast were equalized and scrambled-image controls helped isolate emotional effects from visual luminance.
A second experiment used 102 new participants and removed images entirely. Subjects listened to 30-second audio clips from films and other media while fixating on a cross, then rated their emotional states.
Across both experiments, higher self-reported disgust predicted sustained pupil dilation. Sadness also predicted dilation but less strongly. Fear showed dilation only in late portions of some audio clips. Anger produced the clearest contrasting pattern: in the longer audio task, reported anger was associated with pupil constriction. Happiness produced a small dilation effect in the tests.
The authors link these patterns to autonomic nervous system routes: dilation reflects sympathetic activation, which can broaden visual sampling, while constriction reflects parasympathetic activity associated with narrower, focused vision. They note the results support the idea that some basic emotions have distinct peripheral signatures.
The paper flags limitations. Data were collected in controlled lab conditions with artificial stimuli. The design depends on self-report, which can blur subjective labels. The authors suggest follow-up work on delayed, post-exposure pupil changes and testing responses in more naturalistic settings.
The study is titled "Differences in Pupil Size During Self-Reported Experiences of Disgust, Sadness, Fear, Anger, and Happiness" and lists Kate McCulloch, Edwin S. Dalmaijer, Gerulf Rieger and Rick O’Gorman as authors.
Photo credit: www.psypost.org
Tags: pupilometry, autonomic nervous system, eye-tracking, emotion, self-report
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