Verified by 
The concept of facial beauty is universally and intuitively understood, yet defining beauty is challenging. For centuries, people have attempted to define “beauty” using a variety of mathematical models. Recent social science research has identified four key components that make up beauty: symmetry, averageness, sexual dimorphism and youthfulness.
One common underpinning for these ideals is the necessity for visual input to assess them. This raises the question: how do those with impaired vision perceive beauty in others? A recent study published just this month suggests that nonvisual cues trigger processing in parts of the brain that can reliably detect beauty when the ability to see is hindered.
In this study, a total of 8 blind and 10 nonblind male subjects were enrolled and asked to rate 6 different female models on a 1 to 10 scale. One by one, the 6 models entered a secure room without any outside noise or distractions and were seated 3 feet across from the subjects for 30 seconds without any interactions. There was no talking, physical contact or communication between the model and blind/nonblind subjects and ratings were provided after the models were out of the room. The models were instructed to not wear makeup, perfume, scented soaps or shampoos, loud jewelry or high heels. This process was then repeated until each subject rated each of the models. Following this, both the blind and nonblind subjects were blindfolded and the same process was repeated with the models entering in a different random order.
The results of the study showed that the models the sighted participants rated as beautiful were consistent with those the blind rated as beautiful. The sighted but blindfolded subjects, however, did not have this same ability to accurately detect beauty when their sense of vision was removed. Notably, the sighted and non-blindfolded subjects had an inter-class correlation of beauty ratings of 0.900 while not masked but then significantly decreased to 0.458 when masked. The ability of these sighted individuals to judge beauty thus decreased from excellent to poor simply by masking. This indicates that sighted observers do not have the skills for detecting beauty without vision that blind observers do.
There are two main ideas that may help us understand the results of this study: survival and pheromones. Functional MRI studies of blind individuals have shown that both danger and beauty have been shown to activate the amygdala, a part of the brainstem. From an evolutionary perspective, it would make sense that the same pathways that detect danger could also detect beauty, because both things can be important to survival and procreation.
The second part of the explanation for these results suggests that pheromones drive the ratings of beauty for blind observers. This association of beauty and body scent has long been established. In this study, the model with the highest beauty rating from both the blind and nonblind was in her mid-ovulatory cycle and not on oral contraceptives suggesting that her expressed pheromones signaled her ovulation.
This recent study provides an important perspective on the definition of beauty. While many of us focus on body ratios and facial proportions as the hallmarks of attractiveness, we now have scientific data confirming the wisdom of the ages: beauty is more than skin deep.
