The concept that we reveal our true emotions with facial expressions was proposed in 1872 by the famous evolutionist Charles Darwin in his work: The Expression of the Emotions in Man and Animals.
Darwin believed that mammals revealed their emotions with their faces.
However, the subject was not taken very seriously until the 1960’s, when Paul Ekman, a professor of psychology at the University of California, began studying the topic of facial coding.
Following his numerous trips abroad, he concluded that facial expressions such as fear, anger, sadness, joy, and surprise could be considered universal, biological, and therefore valid in all cultures.
In collaboration with Dr. Maureen O’Sulllivan, Ekman also developed a study, called the Wizards Project, on micro-facial expressions in order to understand if people were telling the truth or if they were lying.
These are small involuntary alterations in facial expression that may indicate, for example, anxiety and discomfort.
It turned out that only a small percentage of people could recognize deception naturally.
Ekman called these people the Truth Wizards.