Humans have 21 facial expressions: Computer aids scientists to detect beyond six basic emotions


Scientists have now determined that humans can make up to 21 facial expressions. The new study computers to map the emotional expressions, which ranged from "sad" to "happily disgusted."

The study was conducted by researchers from the State University of Ohio. The research team was able to use computers to distinctly identify specific facial expressions. Before the study was completed, scientists believed that humans could only make around six expressions. The results of the new study was just tripled that number.

Most people will be able to identify basic emotional expressions like being happy or sad. However, the team was able to go a lot further by mapping out expressions like fearfully disgusted or even angrily surprised.

"We've gone beyond facial expressions for simple emotions like 'happy' or 'sad.' We found a strong consistency in how people move their facial muscles to express 21 categories of emotions," said Ohio State University cognitive scientist Aleix Martinez. "That is simply stunning. That tells us that these 21 emotions are expressed in the same way by nearly everyone, at least in our culture." Martinez is also an associate professor of electrical and computer engineering.

The results of the study will have a wide variety of applications in different fields. Aside from being able to accurately identify what another person is expressing, the computer models created by the team may also be used to create more effective treatment plans for specific mental problems such as post-traumatic stress disorder (PTSD) or even autism. The team published its findings in the online journal the Proceedings of the National Academy of Sciences.

"For example, 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," said Martinez. "Then eventually we can begin to understand these disorders much better, and develop therapies or medicine to alleviate them."

Cognitive scientists have long identified the six human emotions as sadness, anger, fear, disgust, surprise and happiness. Unsurprisingly, these emotions are also linked to the most easily identifiable human facial expressions. However, the human brain is much more complex and six basic emotions alone would not be enough to contain the full emotional spectrum that humans can show.

"In cognitive science, we have this basic assumption that the brain is a computer. So we want to find the algorithm implemented in our brain that allows us to recognize emotion in facial expressions," Martinez said. "In the past, when we were trying to decode that algorithm using only those six basic emotion categories, we were having tremendous difficulty. Hopefully with the addition of more categories, we'll now have a better way of decoding and analyzing the algorithm in the brain."

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