What happens in the brain when two people are ‘in sync’?

Human interactions shape daily life, from simple conversations to deep emotional exchanges. Understanding what happens in the brain during these moments is a growing area of research.

Scientists have long studied individual brain activity, but only recently have they begun examining how two brains become “in sync” during communication.

A new study brings this research closer to real life, moving beyond controlled laboratory settings. It explores how people’s emotions and language structures influence neural activity when they interact.

Conducted by researchers from the University of Trento and Nanyang Technological University in Singapore, the study provides fresh insights into human connection at the neural level.

The findings reveal that brain synchronization plays a crucial role in shaping social bonds.

Brains “sync up” during conversations

Traditional neuroscience studies often rely on artificial settings, where participants follow strict instructions. This research takes a different approach. By allowing natural conversations and spontaneous interactions, the scientists aimed to capture real-life social dynamics.

“For the first time, we have combined AI techniques to neuroimaging measurements obtained on two people at the same time,” noted Alessandro Carollo, first author of the study.

“We have worked in a laboratory setting, but we tried to create less controlled situations than usual, so that each participating couple was free to invent a dialogue as well as to imagine giving each other a gift and being surprised to receive it.”

The study involved 42 pairs of participants, totaling 84 individuals between the ages of 18 and 35. Each pair engaged in different interactive tasks, allowing researchers to analyze brain activity under various conditions.

Brains sync in the prefrontal cortex

Communication is more than just words. It involves emotions, gestures, and an intricate exchange of signals between people. The researchers found that brain activity becomes synchronized when two individuals interact, particularly in the prefrontal cortex, which is associated with higher cognitive functions.

“We combined artificial intelligence techniques with the most advanced brain imaging technology to study how emotions and the structure of language influence brain activity in interactions,” noted Gianluca Esposito, one of the corresponding authors.

“This study reveals that, when two people interact, their brain activity is synchronized, especially in the prefrontal cortex. Emotional content and the structure of language are connected to this neural synchrony.”

By linking emotional tone and language structure to neural synchronization, the researchers provided strong evidence that the way people communicate directly affects their brain activity.

Artificial intelligence and neuroimaging

To analyze interactions, the researchers used artificial intelligence to process dialogue transcripts.

Every conversation was first transcribed by hand, then AI techniques helped extract emotional and linguistic patterns. This allowed the team to quantify the impact of different communication styles on brain function.

For neuroimaging, they relied on functional near-infrared spectroscopy (fNIRS), a technique that measures changes in blood oxygen levels in the brain. fNIRS is non-invasive, portable, and ideal for studying real-time interactions between two individuals.

Unlike traditional brain imaging techniques, it allows participants to move and speak naturally.

Studying social interactions

Studying real-world conversations requires methods that do not interfere with natural behavior. Functional near-infrared spectroscopy provides an effective solution by allowing researchers to measure brain activity without restricting movement.

“It is an easy-to-carry and lightweight technique: it only takes a small box with a pair of caps and their cables. Then you plug it into a laptop computer and that is all you need to study human interactions,” noted Carollo.

By making neuroimaging more accessible, this technique paves the way for further research outside laboratory settings.

From the lab to everyday life

One of the study’s main goals was to take brain research beyond the controlled environment of a lab. Real-life interactions are complex, and understanding them requires studying people in natural settings.

The findings suggest that brain synchronization is a fundamental part of human connection, influencing how people respond to each other in various social situations.

“The best approach seems to be the transdisciplinary one, which integrates emotional content and semantic/syntactic information. The results obtained on neuronal synchronization have a number of interesting implications,” said Esposito.

“The study shows that emotions and language structure influence our conversations and the neural processes that then guide how we interact with each other. This opens up new avenues for research into human interactions.”

Understanding human relationships

This study lays the foundation for further exploration of how brains sync up in different social contexts.

Future research could examine interactions between family members, romantic partners, or colleagues. It could also help improve communication-based interventions for individuals with social difficulties.

By combining artificial intelligence with neuroimaging, scientists can now gain deeper insights into the brain’s role in everyday communication.

As this field advances, it has the potential to transform how we understand human relationships, making it possible to study real-life connections in ways never before imagined.

The study is published in the journal NeuroImage.

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