McGill researchers have demonstrated something long assumed: that glances can transmit information about one’s mental state to others without a single word being exchanged. They speculate that this primal ability may have played a role in assuring survival of human society at times when making a sound could have attracted predators.

“Humans have a long history of living in complex groups and social situations. It has been theorized that this has led our brains to develop a heightened ability to focus on social cues from faces, and especially from eyes,” said Jelena Ristic, a Professor in McGill’s psychology department. She has been working in the field for over 20 years. “It’s a system that has evolved to support very quick exchanges of complex social information.”

“Gaze-following is thought to provide a foundation for our social development and behaviour. It helps us to understand what others are thinking, looking or wanting, as well as to connect with them mentally, so we follow where others are looking quickly and spontaneously. Even young human infants and primates do it,” she said. 

Ristic is the senior author on a research paper describing a series of seemingly simple experiments in which participants viewed videos in which people on screen looked either right or left. Sometimes the subjects on screen had been instructed to look in one direction or the other, and other times they were allowed to choose where to look. Videos were paused just before the subjects moved their eyes, and the observers were asked to predict the direction that the subjects were going to look next. 

The researchers discovered that when the people on screen were free to choose the direction of their gaze – what the researchers called “intentional looks” – the observers’ rate of accuracy was not affected. However, those who predicted correctly were able to do so more quickly.

In other words, the observers were able to glean intentions in the eyes before any action had taken place.

“The speed of the observers’ responses suggests that they implicitly recognize and respond more quickly to intentional eye movements. It also told us how sensitive we are to information about the mental state and intentions conveyed by the eyes,” said Florence Mayrand, a PhD candidate in the Department of Psychology and the paper’s first author.

To try to understand why observers were able to guess eye-shift direction more quickly when people on screen had been left free to choose the direction in which they would look, the researchers analyzed the amount of motion available in the eye movement video. More movement was found in the area near the eyes right before the gaze shift when the gazers could choose freely where to look than when they had been told which way to look. This suggested to the investigators that intentional looks are marked by specific movement patterns. 

To further understand whether intentional looks have any special physical properties to which people are inherently sensitive, the researchers are currently measuring the speed, trajectory, duration and the number of blinks and blink characteristics for intentional and directed looks in a new sample of study participants. 

Following this, they plan to examine whether these fundamental properties differ according to the intentions of the person looking in one direction or the other, for example, whether they are intending to deceive or help; how the ability to read intentions from eye gaze develops; what its underlying brain mechanisms are; and whether there any differences in sensitivity to intentions in gaze for groups with social difficulties, such as adults or children with autism or ADHD.