14 DAY TRIAL // Our brain chooses people we like over shared interests, found a new study led by graduate student Fenna Krienen and senior author Randy Buckner, PhD, of Harvard University, focusing on the brain region that processes social information.
Friends trigger more response in people's brains than strangers do, and this even if the stranger has more things in common.
The researchers analyzed the way that the medial prefrontal cortex and associated brain regions recognized someone's value in a social situation, wandering if they would respond more to people we know, or to those with whom we have things in common.
For this, the team imaged the brain activity of 32 participants, while they were judging how well lists of adjectives described their personalities, in order to identify the regions of the brain that responded to personally relevant information.
In a different experiment, 66 other participants gave personal information on them and two other friends, one friend who they thought had similar preferences and the other who was different.
The authors of the study then established similar and dissimilar strangers for each volunteer, according to their personality profile.
Finally, the participants were placed in a scanner, where they played a game in which they had to guess another person's answer to a question.
What the authors found was that the activity in the medial prefrontal cortex increased when people talked about their friends, while people with common interests made no difference in brain responses.
Krienen said that “in all experiments, closeness but not similarity appeared to drive responses in medial prefrontal regions and associated regions throughout the brain.
“There are psychological and evolutionary arguments for the idea that the social factors of 'similarity' and 'closeness' could get privileged treatment in the brain; for example, to identify insiders versus outsiders or kin versus non-kin.
“However, the results suggest that social closeness is the primary factor, rather than social similarity, as previously assumed.”
The large number of participants and the experimental approach of this study make a strong contribution to the field, according to Read Montague, PhD, of Baylor College of Medicine, an expert on decision-making and computational neuroscience.
The research was supported by the National Institute on Aging, the Howard Hughes Medical Institute, the Simons Foundation, the US Department of Defense and an Ashford Graduate Fellowship in the Sciences, and was published in The Journal of Neuroscience.