Connecting Brains: How Interaction Leads to Connection

By Tiago Azzi and Ioanna Giannakou

Picture this: you are sitting in a cozy bar, face to face with an old friend. You have been chatting for the past hour and can’t wipe the smile off your face. You feel understood, light, and at ease. More than anything, you feel connected. And here’s a thought: if all the talking, listening, thinking, and remembering you have been doing together are powered by your brain, could your brain activity actually be syncing with your friend’s? Could your minds be “on the same wavelength”?

To explore this idea, let’s first dive into what’s happening in our brains. When groups of neurons in a specific brain region fire together rhythmically, they produce what scientists call “oscillations,” or more simply, brain waves, which come in different frequencies. The low-frequency delta (0.5–4 Hz) and theta (4–8 Hz) waves are associated with sleep, relaxation, and memory, while higher-frequency waves, like alpha (8–12 Hz) and beta (12–30 Hz), are linked to focus, movement, and active thinking¹.

If one brain alone produces these waves, what happens during social interaction? Just as your neurons fire in rhythmic patterns, so do your friend’s, and research suggests these rhythms can sometimes line up. When the activity in two brains becomes aligned in this way, researchers refer to this phenomenon as inter-brain synchrony (IBS)². This doesn’t mean your thoughts are identical, but rather that only certain rhythms in brain signals are in harmony, including those linked to attention, emotion, or language. Scientists have found that our brains often show synchronized patterns in specific social interactions, as if tuned to a shared neural frequency². Crucially, IBS is not driven by a single source (Fig. 1). Instead, it is shaped by outside cues, internal traits and states, as well as dynamic social behaviours like conversation and eye contact³. However, it is still unclear precisely how these different factors interact.

How Does IBS Work?

The Closer, the Better?

Why does your interaction with your long-lost friend bring certain brain rhythms into alignment, while other types of interactions do not? Social closeness may hold the key to this question, as IBS gets a noticeable boost when we interact with people we feel close to. Think of social closeness as the degree to which your sense of “me” overlaps with your sense of “you”⁴. This feeling has been linked to increased neural alignment during shared experiences, especially collaborative ones.

From these observations, some patterns have emerged. For instance, delta-band oscillations, associated with speech comprehension⁵, are likely contributors to the neural synchrony observed when people are simply listening and responding to one another. Beta synchrony has also been linked to functions such as language processing and motor coordination⁶. Notably, during social interaction between those with close bonds, such as friends or romantic partners⁷, beta waves tend to synchronize more.

However, the pattern shifts for strangers. One study, for example, found that unfamiliar pairs showed higher beta-band IBS in certain brain areas during tasks involving empathy⁸, compared to close pairs. Researchers suggested that unfamiliarity may actually demand more neural effort to connect, while close partners rely more on shared behaviour and intuition. Taken together, these findings suggest one clear conclusion: our brains synchronize in distinct ways depending on the relationship, the partner’s familiarity, and even the specific brain frequencies we observe.

The Power of Language

Language might also play a key role here. Have you ever noticed that when you speak a foreign language, it can feel harder to truly “connect”? It turns out this feeling is not merely about vocabulary or grammar, as your brain may actually synchronize differently with the person you are engaging with. Research suggests that the language we use in social interactions, whether our native tongue or a second language, can influence how our brains align with others⁹. In fact, conversations in a shared native language tend to result in more widespread IBS than those in a non-native or mixed-language setting¹⁰. 

But how does this happen? One theory suggests that language acts as glue in social interactions, linking core aspects of identity to our connections with others¹¹. When we switch to a foreign language, that glue may weaken. As a result, even when people use the same words, their emotions, and consequently their neural synchrony, might not align in the same way. So next time you find it harder to connect in another language, do not blame your accent or proficiency. Your brain may simply be speaking at a different rhythm!

IBS Put into Context

An Era of Digital Connections

In our increasingly digital world, it is natural to ask: does having a Zoom call with a long-lost friend induce the same type and level of brain synchrony as chatting together over drinks? The answer appears to be no, or at least not entirely. Studies comparing in-person and remote interactions have found that face-to-face communication elicits stronger neural synchrony, particularly in brain regions involved in social cognition¹².

This heightened synchrony has been linked to rich nonverbal cues such as eye contact, facial expressions, and micromovements, which are often lost in virtual settings. That said, online interaction is not completely out of sync. Remarkably, people collaborating through remote multiplayer games, even without video or audio, still show IBS in alpha, beta, and gamma bands⁷. It seems that shared attention and joint action can drive brain alignment, even when we are not physically together. So, while your brains may not click in quite the same way over video, some neural resonance can still occur through a screen.

Creating Synchrony: A Tool for Learning

Having seen how IBS can occur in both face-to-face and online interactions, the question remains: what is the purpose of IBS in both our physical and digital connections, and how can we use it to our advantage? One intriguing answer comes from schools and educational settings. Picture a classroom where students and teachers do not just exchange words but where their minds align. Does that sound like science fiction? We believe that it is not. Research indicates that IBS can predict which students learn most effectively. In one study, students whose brainwaves matched more closely with their teachers’ during a lesson scored higher on memory tests¹³. Another study revealed that greater synchrony in students’ brain patterns went hand in hand with higher engagement and stronger social connection⁴.

Building on this, researchers have even used dual brain stimulation to manually induce synchrony between individuals’ brains and observed both better coordination and improved learning outcomes¹⁴ (Fig. 2). In other words, IBS may be what drives effective teaching rather than just a by-product. Whether through eye contact or movement, being on the same wavelength could be the key to both better learning and stronger connection.

The Debate Surrounding IBS: Too Good to Be True?

You might think that IBS sounds almost unbelievable. Two brains lighting up in harmony during a deep conversation or shared task? Some scientists argue that this neural synchronization could simply reflect something much simpler: coordinated movement. When we interact, we nod and gesture, mirror posture, and even breathe in synchrony with each other without realizing it. This kind of motor synchrony has been shown to strengthen connection, increase likeability, and enhance understanding^15,16. So, is it really our brains synchronizing or just our bodies?

One group of researchers suggests that this physical coordination might drive the observed neural alignment. If two people are tapping their feet or nodding their heads in time, their brain waves could simply be reflecting that shared movement¹⁷. Others, however, believe that IBS is the orchestrating force behind this phenomenon, actively guiding coordination and helping people align their intentions and attention to achieve shared goals¹⁸. Still, it remains unclear whether IBS is a meaningful signal of social connection or simply neural noise from a shared experience.

Brains that Fire Together, Wire Together

So far, we know that IBS is a biological signature of our drive to connect. Whether achieved through shared language, eye contact, or a coordinated task, our brains appear wired to resonate with others. But this resonance is not guaranteed: it depends on who we are, how we interact, and even where we are located. The mere fact that our brains can synchronize during conversation, cooperation, or learning raises exciting questions and opens up new avenues for discovery. Could understanding IBS help us build better classrooms, stronger teams, or more empathetic technologies? Perhaps it could also help bridge social, cultural, and linguistic divides by showing how minds can find harmony.

As we move through a world increasingly shaped by screens and digital encounters, it becomes crucial to consider how we can stay truly attuned to one another. Understanding IBS invites us to look beyond words and into the shared space of attention, emotion, and intention.

Perhaps the next time you’re sitting in that cozy bar, laughing with a friend, you’ll know there’s more at play than just good conversation. Beneath the smiles and shared stories, your neurons may be firing in rhythm with theirs. Connection, after all, is not just something we feel, it is something our brains do together.

About the authors

Both authors have been members of the VU.Sci editorial committee since September 2024, and contributed equally to this publication.

Further reading

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7. Wikström, V., Saarikivi, K., Falcon, M., Makkonen, T., Martikainen, S., Putkinen, V., Cowley, B. U., & Tervaniemi, M. (2022). Inter-brain synchronization occurs without physical co-presence during cooperative online gaming. Neuropsychologia, 174, 108316. https://doi.org/10.1016/j.neuropsychologia.2022.108316 ↩︎
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9. Pérez, A., Dumas, G., Karadag, M., & Duñabeitia, J. A. (2019). Differential brain-to-brain entrainment while speaking and listening in native and foreign languages. Cortex, 111, 303–315. https://doi.org/10.1016/j.cortex.2018.11.026 ↩︎
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13. Davidesco, I., Laurent, E., Valk, H., West, T., Milne, C., Poeppel, D., & Dikker, S. (2023). The temporal dynamics of brain-to-brain synchrony between students and teachers predict learning outcomes. Psychological Science, 34(5), 095679762311638-095679762311638. https://doi.org/10.1177/09567976231163872 ↩︎
14. Pan, Y., Novembre, G., Song, B., Zhu, Y., & Hu, Y. (2021). Dual brain stimulation enhances interpersonal learning through spontaneous movement synchrony. Social Cognitive and Affective Neuroscience, 16(1-2), 210–221. https://doi.org/10.1093/scan/nsaa080 ↩︎
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16. Davidesco, I. (2020). Brain-to-Brain Synchrony in the STEM Classroom. CBE—Life Sciences Education, 19(3), es8. https://doi.org/10.1187/cbe.19-11-0258 ↩︎
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