Humans have always lived in groups. This complex social lifestyle has shaped our brain, strengthening its ability to decode facial signals – particularly those coming from the eyes. “It is a system that has evolved to allow very rapid exchanges of complex social information“, explains Jelena Ristic, professor in the psychology department at McGill University, in a press release.
To deepen the understanding of gaze mechanisms in social interactions, Jelena Ristic and her team conducted a series of experiments involving between 70 and 81 volunteers. These participants watched videos where people looked left or right. Sometimes these eye movements were spontaneous, other times they were deliberately provoked. The sequences stopped just before the movement took place, and the participants then had to guess in which direction the gaze was going to be directed.
The results? The rate of correct responses remained stable, but the speed of responses increased when gaze was intentional. “The reaction speed of observers suggests that they unconsciously recognize intentional eye movements, and react to them more quickly“, specifies Florence Mayrand, doctoral student in the psychology department at McGill University. In other words, we know how to perceive the intention behind a look even before it is fully manifested.
To explain this phenomenon, the researchers examined the micro-movements that precede eye movement in videos. In the journal Communications Psychology, they explain that they discovered that intentional gazes were accompanied by more marked activity around the eyes, reflecting the existence of particular motor patterns. It is this subtlety that our brain would instinctively capture, like a sort of invisible signature of intention.
In the future, scientists would like to accurately measure blink speed, trajectory and frequency in different gaze types. They would also like to determine whether these elements vary according to intention (lying, helping, fleeing) or according to observer profiles, particularly in people with disorders such as autism or ADHD.
Reading eyes is therefore not a magical power. It is a skill deeply ingrained in us, essential to the survival of our ancestors, and still at work in our daily interactions. Behind each movement of the gaze, an intention emerges. And our brain, without us even being aware of it, often knows how to decipher it.