Brains in synchrony – the magic of being on the same wavelength

Time for teamwork! Which feelings does this announcement trigger in you? In this blog post, we explore how social neuroscience studies brains during social interaction and what it means to be on the same wavelength.

Imagine, it’s Monday morning. You go to work with an uneasy feeling because today, you have to start working on a new project with this particular colleague you don’t like. From previous projects, you know that it is somehow really hard to work together with this person. You say or do something and it always feels like you’re talking at cross purposes. It’s not only about sympathy, you really feel like you are not on the same wavelength.

And you could be right. Literally.

Working together with another person is a complex and dynamic act of coordination for your brain. Fortunately, the human brain is usually very well prepared to accomplish this task. According to the social brain hypothesis, evolution has shaped our brains to be hard-wired for social interaction (for more on our social brain, read this post). There are specific brain regions and circuits that are dedicated to the processing of social stimuli (e.g. the mentalizing or the mirror neuron network).

However, we still do not know what exactly is going on in our brains when we interact or work together with another person. Considering the importance of social relationships and teamwork in our private and work lives, researchers are trying to understand the neural mechanics of social interaction. What is it that constitutes good teamwork from a neuronal perspective? What are the neural mechanisms underlying and facilitating human interaction?

Research on social interaction

These questions are addressed by researchers in the field of social neuroscience. Social neuroscience contributes to our understanding of human sociality by studying the neuronal processes underlying emotions, empathy, intentions, and so on. But how do researchers do this?

Traditionally, social neuroscience relies on methods that study how individual brains react to social stimuli. A simple experimental set-up looks like this: You are lying as still as possible in a noisy, narrow fMRI scanner and stare up to a screen on which photos of other people in turn with pictures of objects are shown to you. By analyzing your brain data, the researcher can see that your brain shows a different kind of activation pattern when seeing faces compared to objects. Whenever you see a person, a particular part of your brain is activated: your social brain!

Although this approach has led to the important characterization of different components of the social brain, it has often been criticized for its limited ecological validity. As you might intuitively see, there is a difference between interacting with an actual person compared to merely seeing a picture or video of that person. Similarly, results generated in a sterile lab environment are hard to transfer to real social exchange. To fully understand the neural mechanics of social interaction, neuroscientific experiments should study real-life interaction during which both persons are present.

To address this methodological problem, some researchers are calling for a move from what has been termed “one-person neuroscience” towards a “second-person neuroscience” approach. In this paradigm, two or more interacting brains are scanned or recorded at the same time (= hyperscanning) using for example dual-fMRI or EEG. Hyperscanning allows to capture what is really going on between two brains at the very moment of interaction – which offers more valid and fascinating results about the nature of everyday human social interaction.

Inter-brain synchronization

What did researchers discover using these methods? In several studies, researchers have observed a phenomenon that could not have been discovered looking at individual brains alone: inter-brain synchronization, which basically means that when people are doing something together, their brain waves tend to synchronize and look similar.

Most studies that found inter-brain synchronization used the method of hyperscanning EEG while participants were engaged in a joint activity.  EEG uses electrodes to record the brain waves (= oscillations) measured at the participant’s skull. For example, Dumas and colleagues (2010) discovered coherent brain oscillations between partners, when one partner imitated the hand gestures of the other. Sänger, Müller, and Lindenberger (2012) found out that pairs of guitar players showed synchronization in low frequency ranges in frontal and central areas when playing a piece of music together. A similar pattern could be observed in a study about romantic kissing (2014): the two brains of kissing partners were literally “coupled” via their brain waves.

These EEG studies suggest that doing something together requires so-called interpersonal action coordination which seems to be supported by synchronous brain activity. But, you may have noticed that the above-mentioned studies all involved similar kinds of perception and movement patterns of the persons involved – which may explain the occurrence of similar brain patterns. Is there really a social aspect to it? And what about other types of teamwork?

Teamwork – why does it feel easier with some and not with others?

In a series of experiments, Szymanski and colleagues (2017) investigated the neural mechanics of teamwork. They used a slightly different approach to investigate the phenomenon of neural synchronization: in their experiments, participants were asked to attend visual stimuli together (= joint attention). According to them, joint attention is a core feature of teamwork: when working together, both parties need to pay attention to the same thing. Using joint attention instead of joint movement allows to pinpoint the social aspects of joint action independently of movement: Subjects either attend a visual stimulus alone or jointly with somebody else next to them without changing their posture. The important difference between the two situations is the presence or absence of another person and consequently, of social interaction.

In their primary study, participants were engaged in a visual search task during which they were looking for a target object amongst many distractors on a shelf. At the same time, their brain waves were recorded with EEG using the hyperscanning approach. Following the logic explained above, participants did this task twice: once individually and once together with another person. In the teamwork condition, participants were sitting next to each other and were allowed to interact in any way they wished (without disturbing the EEG recording too much). By analyzing the recorded EEG data, the researchers could observe increased within- and between-brain phase synchronization when performing the task together.

However, not all teams profited from doing the task together. Some teams performed better than others: those teams with the highest phase synchronization were more efficient and made faster decisions in the task. From this finding, Szymanski and colleagues conclude that phase synchronization can be regarded as the neural underpinning of social facilitation. This means, if your brain activity synchronizes well with someone else during a joint task, it is more likely that you can work together better.

Can brain waves be artificially synchronized via electrical stimulation?

Think again of your disliked colleague described in the beginning. When you were working with this colleague before, your brains were probably not well synchronized. Nevertheless, you have this project you need to finish together. Why not try to make things easier for you? What if you could somehow manipulate your and your colleague’s brain activity to make you tune in to the same wavelength that would enhance your inter-brain connection?

A similar question has also been investigated by Szymanski and colleagues. In this study, participants were assigned to pairs sitting back-to-back and asked to drum together as synchronously as possible. At the same time, to facilitate inter-brain oscillatory synchrony, their brains were stimulated using hyper-transcranial alternating current stimulation (hyper-tACS). Hyper-tACS is a technique that uses electrical stimulation to modify brain activity of two or more subjects simultaneously. The application of two different types of hyper-tACS stimulation was expected to either increase or disrupt ongoing intra-brain synchronization. Consequently, this manipulation was expected to affect how well the pair would be able to synchronize their drumming rhythm.

However, the results of the study were not as expected. In comparison to the sham (no stimulation) condition, only drum asynchrony could be influenced by hyper-tACS. Hence, the researchers could only make their participants’ performance worse. From this result the researchers conclude that the artificial modulation of participants’ brain activity actually could have hindered their natural inter-brain synchronization. Although it was not possible to precisely boost inter-brain synchronization in this study (due to a range of technical limitations), as science progresses it might become possible. Until then, sorry, you have to rely on your natural ability to connect and to coordinate your actions with someone else.


The neuroscientific study of human social interaction is still in its beginnings. With the turn towards two-person neuroscience, new fields of possibilities have opened up: hyperscanning techniques make it now possible to investigate the human brain during dynamic live interaction. Using these techniques on human beings during joint action revealed that synchronized brain wavelengths seem to play an important role in facilitating social interaction. So in the end, the idiom “being on the same (or different) wavelength” actually has some biological truth to it.

Key References

Dumas, G., Nadel, J., Soussignan, R., Martinerie, J., & Garnero, L. (2010). Inter-brain synchronization during social interaction. PLoS ONE, 5(8): e12166.

Müller, V., & Lindenberger, U. (2014). Hyper-brain networks support romantic kissing in humans. PLoS ONE, 9(11): e112080.

Sänger, J., Müller, V., & Lindenberger, U. (2012). Intra- and interbrain synchronization and network properties when playing guitar in duets. Frontiers in Human Neuroscience, 6: 312.

Schilbach, L., Timmermans, B., Reddy, V., Costall, A., Bente, G., Schlicht, T., & Vogeley, K. (2013). Toward a second-person neuroscience. Behavioral and Brain Sciences, 36(4), 393-414.

Szymanski, C., Müller, V., Brick, T. R., von Oertzen, T., & Lindenberger, U. (2017). Hyper-Transcranial Alternating Current Stimulation: Experimental Manipulation of Inter-Brain Synchrony. Frontiers in Human Neuroscience, 11: 539.

Szymanski, C., Pesquita, A., Brennan, A. A., Perdikis, D., Enns, J. T., Brick, T. R., … Lindenberger, U. (2017). Teams on the same wavelength perform better: Inter-brain phase synchronization constitutes a neural substrate for social facilitation. NeuroImage, 152, 425–436.

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