The study was published in the US journal Proceedings of the National Academy of Sciences. Their work identified 21 emotion categories on the human expression, based on unique combinations of muscles of the face. Elaborating this study, the researchers Shichuan Do and Yong Tao photographed 230 volunteers in many different emotional situations and analyzed the resulted 5,000 images with a Facial Action Coding System.
To express the happy state, the participants in the study were drawing up the cheeks and stretching the mouth in a smile. To express surprise, they opened their eyes wide and dropped their mouth open. The study’s results have impact in various domains, from teaching the acting to better understand the psycho-pathologies, as post traumatic stress disorder for example.
The scientists even said that it is however possible to identify other emotion categories.
