Attractiveness in the eyes: A possibility of positive loop between transient pupil constriction and facial attraction

Abstract

Contradictory to the long-held belief of a close linkage between pupil dilation and attractiveness, we found an early and transient pupil constriction response when participants viewed an attractive face (and the effect of luminance/contrast is controlled). While participants were making an attractiveness judgment on faces, their pupil constricted more for the more attractive (as-to-be-rated) faces. Further experiments showed that the effect of pupil constriction to attractiveness judgment extended to intrinsically aesthetic visual objects such as natural scene images (as well as faces) but not to line-drawing geometric figures. When participants were asked to judge the roundness of faces, pupil constriction still correlated with their attractiveness but not the roundness rating score, indicating the automaticity of the pupil constriction to attractiveness. When pupillary responses were manipulated implicitly by relative background luminance changes (from the pre-stimulus screen), the facial attractiveness ratings were in accordance with the amount of pupil constriction, which cannot be explained solely by perceptual brightness induced by simultaneous or sequential luminance contrast. The overall results suggest that pupil constriction not only reflects but, as a part of self-monitoring and attribution mechanisms, also affects facial attractiveness implicitly.Significance Statement: Pupil constriction not only reflects but also affects aesthetic appraisal evaluation, at least under certain conditions. This uncovers a heretofore unknown tight link between pupil constriction and attractiveness. These findings have profound implications with respect to the well-known theories in the James-Lange tradition concerning mind-body interaction. They also provide new clues to the neurophysiological mechanisms underlying attractiveness decisions and to implementing 3 various real-world applications such as BMIs (brain-machine interfaces) and marketing strategies.

Glossiness perception and its pupillary response

“…Although the observers were instructed to focus on the fixation point at the center of the display, their line of sight may have been misaligned, and such a luminance difference would have affected the pupil diameter. Thus, we computed local luminance changes within one degree of the visual angle of the gaze point (Liao et al, 2020) at the early stage, based on recorded eye movements of the observers, and these changes and pupil size were not significantly correlated ( r = 0.19, p = 0.24). Likewise, there was no significant correlation between the object area and pupil size ( r = -0.19, p = 0.24).…”

“…To understand this, we focused on recording the pupillary response to elicit cognitive processing affected by glossy objects. Pupillary responses reflect not only physical factors derived from luminance, but also cognitive factors such as emotional (Bradley et al, 2008; Kuraguchi & Kanari, 2020, 2021; Laeng et al, 2013) and attractive (Liao et al, 2020) stimuli. These reactions are controlled by the locus coeruleus, which affects the level of arousal (Aston-Jones & Cohen, 2005; Benarroch, 2009).…”