By Kaden Paz Leyva

The Princeton Social Neuroscience lab is tucked into the basement of the Peretsman Scully Hall.

Inside, the lab has enough space for two people to be scanned at the same time as they talk, argue and laugh about their moments together. On the other side of the room with a computer system, a researcher charts their brain activity over time, searching for the moments when the two minds move together and the moments when they become disconnected.

The intensity of this work is deserving of the lab’s unofficial motto: “Your brain is on my mind.”

The lab studies and specializes in how people understand their own minds and that of others. Their research includes guessing what a friend is thinking and the tension one feels with a stranger. But the researchers themselves say that the lab is not only trying to answer the neurosociological questions of the mind. It’s also trying to make their research reach beyond academia, in language and in papers that people beyond the field may be interested to read. This makes the lab one-of-a-kind. 

The goal of their distinctive work, hyperscanning, lies at the center of the lab. It works by placing two people in the MRI machine simultaneously. There, these two people have a conversation and talk about issues in their relationship. Meanwhile, their brains are being measured mid-conversation. Princeton’s building layout allows researchers to run both MRIs simultaneously.

Graduate student Yeaju Kim said the hyperscanning is what drew her to work on the lab in the first place. “I was interested in human social interaction because I thought that the most human thing we could do was talk to each other,” said Kim. “We have our own language and I think that’s a really unique characteristic of our lives.” Watching two people’s brain’s activity align, she said, reveals things much deeper than physical mimicry. It is the moment of synchronization that goes beyond simply moving or speaking the same way. According to Kim, the lab examines “the way to understand the way you think and how others think.”

The research divides the brain scans into roughly 8,000 tiny 3D units called voxels and compares them across two people to see where brain activity overlaps. When researchers overlap the two scans on a 3D scan, it creates zones using different shades of red. Areas of the brain that appear darker means that the two people share similar patterns in their brains. That’s usually seen more between friends than between strangers. 

The process is slow and exacting. Researchers need around 100 hours of running code with the data before beginning to analyze it. Since the lab’s coding platform is prone to breaking down, those in the lab have to learn code from scratch to be able to continue with analysis. 

Through having to monitor simultaneous MRIs, keeping participants still through the scan and making participants comfortable even though they can not see each other’s faces, it’s an intricate process. Kim still said watching the data come together makes the work rewarding. This gives her a rare and thorough window into how people connect. 

Lab manager Amy Nguyen came to the lab with experience largely in developmental and clinical psychology. Nguyen’s outside perspective has shaped how she will communicate and publish the lab’s findings in a language that will be understandable both to people who aren’t already a genius in the field and to those who are an expert.

Researchers in the lab are careful to note that basic science like this isn’t exactly designed to produce immediate applications in the real world. But Nguyen said the couple’s research could eventually help bring different approaches to relationships.

The willingness to explain and look into a more iterative side of research alongside the big findings of a lab is part of what researchers say sets the lab apart. As Nguyen put it, most people seem to picture a wet lab for dissection when they think of neuroscience, not realizing how much of the work is coding, math and careful design.

As the lab continues to study how two minds can be studied at once, the researchers say the bigger goal hasn’t changed: understanding not just how people think but how they think about each other, and making sure that understanding doesn’t stay locked inside a lab.