How many facial expressions can we make?
Charles Darwin was the first to propose that human emotions and the corresponding facial expressions are universal. His idea was dismissed by most scientists until the work of Silvan Tomkins, Paul Ekman, Wallace Friesen, and Carroll Izard established that facial expressions were largely consistent across cultures.
Ekman and Friesen created the Facial Action Coding System, which shows in detail every movement that our mimetic muscles can make.
For many years, it was believed that humans only make six basic facial expressions: happy, sad, disgust, anger, surprise, and fear (contempt is sometimes considered a seventh). Then in 2014, researchers at Ohio State University used a computer to analyze over 5,000 photos and found that instead of just six, there are actually 21 universal expressions: the six basic ones, plus 15 compound expressions like “sadly angry” and “happily disgusted.”
In 2019, Ohio State University researchers discovered even more universal expressions. They analyzed 7.2 million images and found 35 expressions that express emotion in the same way across cultures. They were happy to find that while we use just one expression to convey disgust, three to convey fear, and five each for sadness and anger, humans have 17 expressions to convey a range of happy emotions.
Scientists are motivated to learn more about facial expressions because they want to track how genes, chemicals, and neural pathways control emotion. They hope to apply these findings to treatment of conditions like PTSD, which involves emotional triggers, and autism, which involves a lack of recognition of other people’s emotions.