Your brain reveals who your friends are: Study illustrates how similar neural responses predict friendships

January 30, 2018, Dartmouth College
Social network. The social network of an entire cohort of first-year graduate students was reconstructed based on a survey completed by all students in the cohort (N = 279; 100% response rate). Nodes indicate students; lines indicate mutually reported social ties between them. A subset of students (orange circles; N = 42) participated in the fMRI study. Credit: Carolyn Parkinson.

You may perceive the world the way your friends do, according to a Dartmouth study finding that friends have similar neural responses to real-world stimuli and these similarities can be used to predict who your friends are.

The researchers found that you can predict who people are friends with just by looking at how their brains respond to video clips. Friends had the most similar patterns, followed by friends-of-friends who, in turn, had more similar neural activity than people three degrees removed (friends-of-friends-of-friends).

Published in Nature Communications, the study is the first of its kind to examine the connections between the neural activity of people within a real-world social network, as they responded to real-world stimuli, which in this case was watching the same set of videos.

"Neural responses to dynamic, naturalistic stimuli, like videos, can give us a window into people's unconstrained, spontaneous thought processes as they unfold. Our results suggest that friends process the world around them in exceptionally similar ways," says lead author Carolyn Parkinson, who was a postdoctoral fellow in psychological and sciences at Dartmouth at the time of the study and is currently an assistant professor of psychology and director of the Computational Social Neuroscience Lab at the University of California, Los Angeles.

The study analyzed the friendships or social ties within a cohort of nearly 280 graduate students. The researchers estimated the social distance between pairs of individuals based on mutually reported . Forty-two of the students were asked to watch a range of videos while their neural activity was recorded in a functional magnetic resonance imaging (fMRI) scanner. The videos spanned a range of topics and genres, including politics, science, comedy and music videos, for which a range of responses was expected. Each participant watched the same videos in the same order, with the same instructions. The researchers then compared the neural responses pairwise across the set of students to determine if pairs of students who were friends had more similar brain activity than pairs further removed from each other in their social network.

The findings revealed that similarity was strongest among friends, and this pattern appeared to manifest across brain regions involved in emotional responding, directing one's attention and high-level reasoning. Even when the researchers controlled for variables, including left-handed- or right-handedness, age, gender, ethnicity, and nationality, the similarity in neural activity among friends was still evident. The team also found that fMRI response similarities could be used to predict not only if a pair were friends but also the social distance between the two.

"We are a social species and live our lives connected to everybody else. If we want to understand how the human brain works, then we need to understand how brains work in combination— how minds shape each other," explains senior author Thalia Wheatley, an associate professor of psychological and brain sciences at Dartmouth, and principal investigator of the Dartmouth Social Systems Laboratory.

For the study, the researchers were building on their earlier work, which found that as soon as you see someone you know, your brain immediately tells you how important or influential they are and the position they hold in your social network.

The research team plans to explore if we naturally gravitate toward people who see the world the same way we do, if we become more similar once we share experiences or if both dynamics reinforce each other.

Explore further: Study provides first evidence of common brain code for space, time, distance

More information: Carolyn Parkinson et al, Similar neural responses predict friendship, Nature Communications (2018). DOI: 10.1038/s41467-017-02722-7

Related Stories

Study provides first evidence of common brain code for space, time, distance

February 4, 2014
A new Dartmouth study provides the first evidence that people use the same brain circuitry to figure out space, time and social distances.

Study finds linkage between social network structure and brain activity

May 2, 2017
When someone talks about using "your network" to find a job or answer a question, most people understand that to mean the interconnected web of your friends, family, and acquaintances. But we all have another key network ...

Recommended for you

New study sheds light on brain's ability to orchestrate movement

May 17, 2018
To carry out any action, whether playing the piano or dancing the jitterbug, the brain must select and string together a series of small, discrete movements into a precise, continuous sequence.

Learning music or speaking another language leads to more efficient brains

May 17, 2018
Whether you learn to play a musical instrument or speak another language, you're training your brain to be more efficient, suggests a Baycrest study.

Old drug provides promising new avenue for treatment of MND

May 17, 2018
An international study led by biochemists at the University of Liverpool has shown that the drug-molecule ebselen can correct many of the toxic characteristics of a protein that causes some cases of hereditary motor neurone ...

Our brains are obsessed with being social

May 16, 2018
Our brains are obsessed with being social even when we are not in social situations. A Dartmouth-led study finds that the brain may tune towards social learning even when it is at rest. The findings published in an advance ...

GABA, GABA, GABA, what does it actually do in the brain?

May 16, 2018
Gamma-Aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the brain. It is the control knob of all control knobs. But why GABA? What, if anything, might be so special about the molecule?

For older adults, a better diet may prevent brain shrinkage

May 16, 2018
People who eat a diet rich in vegetables, fruit, nuts and fish may have bigger brains, according to a study published in the May 16, 2018, online issue of Neurology, the medical journal of the American Academy of Neurology.

2 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

Bongstar420
5 / 5 (1) Jan 30, 2018
Yes...this should go without saying. There is a reason humans killed those that wouldn't convert at the end of spiritual evolution to modern religion. If no body noticed, a lot of people cannot be instructed to understand the world any better than you can teach a color blind person to see color. This is why we can't have democracy unless most people learn to override their biases because "rejection" is literally meant to cause death in the long run through reduced fitness by in ability to get cooperative behavior from those controlled by the dominant culture. Its why we put a lot of cognitive energy into ignoring the emotions of rejection. Its rather unfortunate really because our species can no longer afford success by accident. Our environments are not sufficiently large enough relative to us for us to survive without understanding and managing it. People did not historically win because of a correct understanding.
TheGhostofOtto1923
not rated yet Jan 31, 2018
"We are a social species and live our lives connected to everybody else. If we want to understand how the human brain works, then we need to understand how brains work in combination— how minds shape each other,"

-And in order to do that, these academes will have to start acknowledging tribalism and investigating things from that perspective.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.