The link between brain activity and social networks
The structure of the social network to which a person belongs could shape how their brain responds to social exclusion, according to a new study led by a Michigan State University researcher.
The study is authored by assistant professor Ralf Schmälzle, from the College of Communications Arts and Sciences, and published together with a team of researchers at the University of Pennsylvania and the Army Research Lab in Proceedings of the National Academy of Sciences. The researchers looked at the brain’s response to social exclusion under fMRI, particularly in the so-called mentalizing system, which includes separate regions of the brain that help consider the views of others.
“The finding here is that these regions, which are in different places in the brain, show greater connectivity in response to social exclusion,” Schmälzle said. “They go up and down together, almost as if they’re dancing together, doing the same moves over time, and this ‘coupling’ of their activity increases during social exclusion.”
To create the experience of social exclusion, the researchers used a virtual ball-tossing game called Cyberball with 80 boys ages 16-17. While in the fMRI machine, each participant saw a screen with two other cartoon players — who they believed to be controlled by real people — and a hand to represent themselves. All three participants in the game take turns tossing a virtual ball to one another.
For the first phase of the game, the virtual players include the test subject, tossing him the ball frequently. The game then shifts to exclusion mode, and the virtual players stop throwing the ball to the participant.
“During exclusion, people might begin to ask themselves, ‘What might that mean when people are excluding me?” Schmälzle said. “They may ask, ‘Have I done something wrong?’ or ‘Why are they doing this?’ and such kinds of thought might engage mentalizing processes.”
The researchers also were able to access, with permission, the test subjects’ Facebook data, giving them a snapshot of their friendship networks. They found test subjects who showed a greater increase in brain connectivity during social exclusion were those in sparse networks. In sparse networks, the friends of a person tend to not know each other. In dense networks, by contrast, many of a person’s friends are also friends with each other.
“Social network analysis and thinking about social networks has been around a long time in sociology,” said Emily Falk, associate professor at the University of Pennsylvania’s Annenberg School and director of its Communication Neuroscience Lab. “But it’s only recently that these kind of quantitative measures of social networks have been combined with an understanding of the brain. How do your brain dynamics affect your social network and how does your social network affect your brain? We’re at the very tip of the iceberg right now.”
In addition to Schmälzle and Falk, study authors include Matthew Brook O’Donnell, Christopher Cascio and Danielle Bassett, all from the University of Pennsylvania; Javier Garcia and Jean Vettel from the U.S. Army Research Lab; and Joseph Bayer from The Ohio State University.