Thanks to scientists who have ventured outside the laboratory, we have learned that tight-knit groups of females experience synchronized menstrual periods over time, that cohesive groups engaged in decision-making discount dissenting viewpoints in the interests of consensus, and that couples who stay together long enough begin to look alike.
In the wilds of a New York City biology classroom, a new study has captured another group phenomenon known to exist in labs but never before chronicled in humans' natural habitat: group brain synchrony.
Psychology researchers at New York University equipped each of 12 high school seniors with a portable, low-cost electroencephalogram and gathered the gadgets' brain-wave readings over a semester's worth of biology classes (11 sessions lasting 50 minutes each). Writing in the journal Current Biology, the researchers reported that when students were most engaged with each other and in group learning, the readings on their electroencephalograms, or EEGs, tended to show brain-wave patterns that rose and dipped in synchrony.
That neural synchrony was most pronounced when students reported they liked their teacher. Individual students who reported feeling tied to their classmates, as well as those who scored highest on the trait of empathy, were most likely to fall into synchrony with classmates in the course of group learning.
These observations are certainly in line with the phenomenon of neural "entrainment." When everyone in a group is paying attention to the same thing (say, a lecturing teacher or a classroom video), it makes sense that their brain waves will be in sync as a simple function of their mutual attention to a common stimulus.
But the new research suggests that neural synchrony may also reflect something more than just shared attention: It was evident amidmore fluid social dynamics among class members as well, where the give-and-take of group learning might have made for a less uniform experience, said cognitive neuroscientist Suzanne Dikker, who worked on the study.
For an individual, the term "entrainment" is sometimes used to describe "being in the zone." When two or more people are engaged socially with one another, that, too, appears to involve entrainment — or being in the same zone. Such shared entrainment shows up on EEGs as neural synchrony.
"Brain-to-brain synchrony is a possible neural marker for dynamic social interactions, likely driven by shared attention mechanisms," the group wrote.
Indeed, Dikker noted that the project itself was explicitly designed as an effort to gather data in a naturalistic setting. (It did not take measurements of a comparison group of disengaged students.)
The researchers first gave the students a crash course in neuroscience. After enlisting their support in designing the experiment, they helped students craft a few of their own.
"They loved it — at least they said they did," Dikker said. Except during troughs of student attention around college-application time and the inevitable appearance of "senioritis" toward the end of the semester, "they really owned the project," she said.
The idea that neural entrainment in groups can be detected and measured with portable EEGs — and then analyzed to perceive patterns — opens new avenues for research, Dikker added.
The researchers are now designing large-scale projects in which they'll be able to record brain data and other biometrics from up to 45 people at once.
Among the questions they hope to answer: What are the optimal conditions for an audience to experience a performance or movie? Is there an ideal group size? Does having some joint interaction right before a performance improve the experience? How does the audience affect the performer, and vice versa?
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