Brain activity can predict whether strangers will become friends

Foreigners are more likely to become friends if their brain reacts similarly to cinema clips, which suggests that neural activity can predict relationships.

Through cultures, humans tend to surround themselves with people sharing the same ideas. This phenomenon, known as Homophilia, explains why previous studies have found neural similarities between friends. But the researchers did not know if it is because friends wonder more over time or because people revolve towards those who have similar thought processes.

Carolyn Parkinson at the University of California, Los Angeles and his colleagues collected brain scanners from 41 students before starting a higher education program. During analyzes, the participants watched a series of 14 cinema clips covering a range of styles such as documentary or comedy, and various subjects such as food, sports and sciences. The researchers then analyzed the neural activity of each participant in 214 brain regions.

Participants – as well as the other 246 students in their program – carried out an investigation two months later and again after six additional months to ask with whom they liked to spend their free time. People who were friends at eight months had more similar answers in a part of the left orbitofrontal cortex, a brain region involved in the treatment of subjective value, than those who were most distant from the social network-that is to say friends of friends. This effect remained significant even after taking into account the similarities of taste according to the quantity of people who evaluated their own pleasure or their interest in cinema clips.

Two months after the start of the program, the neural similarities with friends and unmiacs were not different, which suggests that people can initially build friendships depending on proximity before finding close friends over time. This was also supported when the researchers examined how friendships changed between the two surveys. Participants who got closer during this period had significantly greater similarities in the activity of 42 brain regions than those that separated. The link remained significant even after taking into account factors such as age, sex and the hometown. “The socio -demographic factors, at least in terms of what we have been able to measure here, seem to simply explain part of the image,” explains Parkinson.

Many of these regions are involved in brain networks that guide attention and help us understand the stories, suggesting that friendships are in part, due to similarities in the way people understand the world around them, explains Parkinson. “People whose reflection processes are more similar find it easier to continue,” said Robin Dunbar at the University of Oxford. “When they say something, they just know what the other thinks because that’s how they think each other.”

Dunbar, who was not involved in research, does not find these surprising results. On the contrary, they confirm what many have suspected for a long time – “this as attracted as, rather than by people launched together by accidents are close to their features,” he said. “In other words, close friends are born, not made.”