March 22, 2014
Researchers Explore Optical Origins Of Different Facial Expressions
redOrbit Staff & Wire Reports - Your Universe Online
The different ways in which the human eyes behave when people make different facial expressions based on various emotions are actually universal, adaptive reactions to various environmental stimuli, according to new research appearing in the March 2014 edition of the journal Psychological Science.
As it turns out, those nearly opposite reactions are rooted in emotional responses which take advantage of how our eyes collect and focus light in order to detect an unknown perceived threat. Their discovery not only counters the notion that such facial expressions did not originate as social communication signals, while also supporting Charles Darwin’s original 19th century theories pertaining to the evolution of human emotions.
“These opposing functions of eye widening and narrowing, which mirror that of pupil dilation and constriction, might be the primitive origins for the expressive capacity of the face,” explained Anderson, who was the senior author of the paper. “And these actions are not likely restricted to disgust and fear, as we know that these movements play a large part in how perhaps all expressions differ, including surprise, anger and even happiness.”
Anderson and his fellow investigators report that the greatest amount of visual acuity results from looks of disgust, which allows the eyes to collect less light and focus better. On the other hand, fearful expressions result in more light and a broader visual field, causing the eyes to be at their most sensitive. Furthermore, our emotions help shape our reality, altering our perception of what we see before the light even reaches the inner part of the eye.
“These emotions trigger facial expressions that are very far apart structurally, one with eyes wide open and the other with eyes pinched. The reason for that is to allow the eye to harness the properties of light that are most useful in these situations,” said Anderson. “We tend to think of perception as something that happens after an image is received by the brain, but in fact emotions influence vision at the very earliest moments of visual encoding.”
Anderson’s team, which also included experts from the University of Toronto and the University of Waterloo, is now analyzing how different types of eye movement ultimately helped facial expressions evolve into a way to support nonverbal communication in various cultures worldwide.
“We are seeking to understand how these expressions have come to communicate emotions to others,” the senior author explained. “We know that the eyes can be a powerful basis for reading what people are thinking and feeling, and we might have a partial answer to why that is.”