Friends share more than interests, their brains are similar too

Grad students watched a variety of videos to help determine how friends' brain waves were similar.
Two friends walk in the woods (Wikimedia)
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Reasons for friendship

It may be no accident that you and your best friend are so alike. We know that people are drawn to others who are like themselves because they have similar tastes, preferences, and they perceive the world around them in the same way. But scientists, including Canadian Dr. Carolyn Parkinson, an assistant professor of psychology and director of the Computational Social Neuroscience Lab at UCLA, wanted to find out if those similarities went deeper, by looking at how their brains respond to real-world stimuli.             

The experiment

Nearly 300 graduate students in the same program were asked to describe their relationship to each other in terms of degrees of separation - friend, friend of friend, friend of friend of friend, and so on. Then a group of 42 of those students were subjected to fMRI brain scans while watching videos that covered a wide range of topics, genres and emotions. The resulting neural responses generated by the scans were then analyzed. The scientists were looking for similar patterns.  

What they found

The researchers found that you can predict who people are friends with by looking at how their brains responded to the videos. Neural response similarity was strongest among those who described themselves as friends, especially in brain regions responsible for emotion, attention, and high level reasoning. These similarities can also be used to predict who your friends are. More research is required to determine if you are drawn to someone because of this similarity, or if you become similar due to influence.