Researchers from The Ohio State University reported on March 31 in the Proceedings of the National Academy of Sciences that they used a computer software called the Facial Action Coding System to analyze approximately 5,000 facial expression photos of 230 individuals, identifying the facial muscles used to express emotions. The results revealed that the unique and recognizable emotional expressions of the human face are more numerous than previously thought.
“For centuries, scientists believed that our expressions could only be categorized into six emotions: happiness, surprise, sadness, anger, disgust, and fear. Our view is that there are at least 21, and it is possible that more expressions will be identified in the future,” said Du Shichuan, the first author of the research paper.
The study indicates that, in addition to the six common basic expressions, people also combine them to create 15 distinguishable compound expressions, such as surprise (happiness + surprise) and sadness-anger (sadness + anger). For example, the characteristics of happiness are: corners of the mouth pulled back, cheeks raised; the characteristics of surprise are: eyes wide open, mouth agape; while surprise combines the features of the first two: eyes wide open, cheeks raised, mouth agape with corners pulled back.
Du Shichuan stated that this achievement is significant for better understanding the pathology of psychological disorders and assisting in the treatment of conditions such as post-traumatic stress disorder.
