The Influence of Age and Facial Image Attractiveness on Pupillary Response

Background:

Facial difference affects quality of life, and ample evidence suggests that social bias and stigmatization often persist even after the provision of high-quality facial reconstruction¹.  Because emotional arousal is reflected in the magnitude of pupillary dilatation^2-4, we have investigated the influence of both facial image attractiveness and observer age on observer pupillary response.  We have also secondarily examined the related effect of facial age (of image, including a subset of images of patients with cleft lip) and cultural background (observer) on attractiveness rating.  

Purpose:

Our aim is to study the visual markers that lead to differential perception of patients with congenital or acquired facial difference by examining the early stages of visual processing. Here we examine the influence of age and attractiveness on autonomic reaction as manifested by pupillary response. This information may better inform surgeons’ conversations with patients by improving their understanding of how faces are reflexively interpreted by others. 

Methods:

118 experimental and 79 control facial images were obtained from the senior author’s practice.

Experimental images included: 29 cleft lip, 22 facial aging, 18 facial lesion, 16 ear deformity, 14 HIV lipodystrophy, 11 nasal deformity, 6 dermatochalasis.

481 subjects rated the images for attractiveness (40 ratings/image). 

Twenty lookzone regions were mapped onto each facial image.

A separate group of 265 subjects observed a randomly chosen subset of 40 images while an infrared eye-tracking camera recorded their pupillary response.

Factorial ANOVA analysis was performed to determine significance of differences between groups.

Outcomes Measured:

Image attractiveness was rated on a 1-7 Likert scale.

Ages of both individual photographed and eye-tracked observer were obtained.

The eye-tracking camera measured average pupil diameter/lookzone region during all image observations.

Results. The following observations were statistically significant at p<0.01 level:

(i)            cleft images: rated less attractive than control images

(ii)          increasing age (image): associated with step-wise decrease in attractiveness in both cleft and control images

(iii)        higher attractiveness (image): associated with larger average observer pupil size

(iv)          increased age (observer): associated with smaller average observer pupil size

Conclusions:

Cleft faces are rated as less attractive, and with increasing age attractiveness diminishes (paralleling the same phenomenon seen with control faces).  Increasing age of the observer is associated with diminishing average pupil size, whereas more attractive facial images stimulate pupil dilation.