Microexpressions

There are seven universal microexpressions: disgust, anger, fear, sadness, happiness, surprise and contempt. They often occur as fast as 1/15 to 1/25 of a second. The face is the best indicator of a person's emotions. Yet, it often is overlooked.
The Definitive Guide to Reading Microexpressions (With Examples)
https://www.scienceofpeople.com/microexpressions/