When people are listening to music, their emotional reactions to the music are reflected in changes in their pupil size. Researchers from the University of Vienna and the University of Innsbruck are the first to show that both the emotional content of the music and the listeners' personal involvement with music influence pupil dilation.
The pupil size reflexively adjusts to the amount of ambient light, contracting in bright daylight and dilating at night. However, pupil size is also modulated by thoughts, emotions, or mental effort.
Using short music excerpts, a team of researchers showed that listeners' pupils indeed dilated in response to emotional music. Excerpts that were judged to be more arousing were associated with larger pupil dilations than calm or relaxing excerpts. "Larger dilations were observed for listeners who reported that music plays an important role in their life." Overall, the results suggest that emotional responses to music are reflected in pupil size, with both the emotional content of the music and listeners' personal involvement with music influencing pupil dilation.