The eyes may be the window to the soul, but your entire face provides both broad and minute clues into your inner emotions. A new computer program developed by researchers at Ohio State University can scan your face and tell you exactly what you're feeling – even if that emotion is something as subtle as "happily disgusted."

All told the computer program can recognize 21 different emotions in subjects' faces – that's three times the number of emotions that could be picked up by previous facial scanners, mostly because cognitive scientists had limited their work into six "basic" emotions: happiness, sadness, fear, anger, surprise and disgust.

The research into these 21 facial expressions was published on March 31 in the Proceedings of the National Academy of Sciences. The research team studied more than 200 volunteers, collecting 5,000 photographs of their facial reactions to various verbal cues. They then looked at how those facial muscles moved, everywhere from the edges of the eyebrows down to the corners of their mouths.

The result? "We found a strong consistency in how people move their facial muscles to express 21 categories of emotions," Ohio State associate professor Aleix Martinez said in a news release. "That tells us that these 21 emotions are expressed in the same way by nearly everyone, at least in our culture."

The original six basic emotions were the easiest to identify – 99 percent of subjects showed happiness by drawing up their cheeks and stretching their mouths into a smile – but the additional 15 emotions weren't that far off. About 93 percent of subjects showed the emotion of "happily surprised" by opening their eyes widely and raising their cheeks in happiness, while their mouths both smiled and opened.

Martinez says this research has a lot of potential for diagnosing or treating conditions that either involve emotional triggers – such as Post Traumatic Stress Disorder (PTSD) – or of conditions that display through a lack of recognition of others' emotions — such as autism. "For example," he said, "if in PTSD people are more attuned to anger and fear, can we speculate that they will be tuned to all the compound emotions that involve anger or fear, and perhaps be super-tuned to something like 'angrily fearful?' What are the pathways, the chemicals in the brain that activate those emotions? We can make more hypotheses now, and test them. Then eventually we can begin to understand these disorders much better, and develop therapies or medicine to alleviate them."

The researchers say this work into cognitive science could also be used to see which genes, chemicals and neural pathways — which can all govern emotions in the brain — express themselves emotionally via facial expressions.

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