The pupil as a measure of emotional arousal and autonomic activation

TLDR

The study aimed to determine whether pupillary changes during picture viewing are mediated by parasympathetic or sympathetic activation. Pupil diameter was recorded while participants viewed pictures, and heart rate and skin conductance were simultaneously measured to assess the influence of hedonic valence and emotional arousal on pupillary responses. Pupillary dilations were larger for emotionally arousing pictures regardless of valence, correlated with skin conductance, and thus support that pupil responses reflect sympathetic arousal during affective picture viewing.

Abstract

Pupil diameter was monitored during picture viewing to assess effects of hedonic valence and emotional arousal on pupillary responses. Autonomic activity (heart rate and skin conductance) was concurrently measured to determine whether pupillary changes are mediated by parasympathetic or sympathetic activation. Following an initial light reflex, pupillary changes were larger when viewing emotionally arousing pictures, regardless of whether these were pleasant or unpleasant. Pupillary changes during picture viewing covaried with skin conductance change, supporting the interpretation that sympathetic nervous system activity modulates these changes in the context of affective picture viewing. Taken together, the data provide strong support for the hypothesis that the pupil's response during affective picture viewing reflects emotional arousal associated with increased sympathetic activity.