21 Human Facial Expressions Defined

Human facial expressions are not as unique as you may think. A recent study has shown that the human face expressed 21 distinct emotions in the same way despite differences in facial structure.

The study, published in the Proceedings of the National Academy of Sciences of the United States of America, used applied computer technologies to identify 21 different facial expressions in the human face.

According to the study, researchers analyzed the facial expression of more than 230 volunteers, who were asked to react to certain verbal prompts by making what they felt was the appropriate face. For instance, a researcher would prompt "you smell a bad odor," and the participant would make their best face of disgust. The participants produced over 5,000 facial images, which were recorded.

Using a nationally recognized body-language database, the Ohio State University research team then  searched for similarities and differences among the participants' expressions using. The team used facial recognition software to match facial movement -- such as the rise or fall of a corner of the mouth -- with common emotions. Surprisingly, the prompts and the associated facial reactions were amazingly consistent among participants, regardless of how different these individuals might look or normally act.

Remarkably, compound emotions, such a happy-surprise, proved distinctly different that happy or surprise, but was still created in the same way by nearly every participant.

What does this mean? For one thing, it shows that the average person has the same understanding of facial reaction as the next guy. However, it should be noted that all these reactions were created on prompt, meaning that they were not genuine.

Another recent study applying computer technologies to facial recognition showed that a computer can more accurately differentiate genuine spontaneous facial expressions from faked voluntary ones.

According that study,  published in Current Biology last March, human focus on facial factors like the eyes gets in the way of comprehending what makes up a genuine reaction -- which includes subtle changes in facial muscles especially around the mouth.

The first study was published in of the National Academy of Sciences of the United States of America on February 28.

The second study was published in Current Biology on March 20.