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When researchers measure the brain activity of multiple people at the same time, something strange happens
“Suddenly you see that things are happening between people that you actually can't see,” says researcher.
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“We have an expression: to be on the same wavelength. It’s not just an abstraction. Research shows that it’s real,” says professor and brain researcher Anne-Kristin Solbakk.
In the early 2000s, researchers began to measure the brain activity in several people at the same time.
Then they discovered something interesting.
When people talk to each other, collaborate, or play music together, their brain waves begin to synchronise.
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Solbakk says that more and more research points to the fact that the synchronisation of brain activity affects what we do.
“We are better at solving tasks, we learn more, and people form bonds more easily,” she says.
Maybe it's the case that when you feel connected to others, it’s actually real?
Your brain activity probably fluctuates in a similar pattern as the people you are with, and all are influenced by each other.
New studies on brain synchrony keep emerging, but what is it exactly?
This is what researchers have found
Hyperscanning, measuring brain activity in multiple people simultaneously, was first done in a study by P. Read Montague and others from 2002.
It opened up new ways of studying interaction between people.
Exciting results have since emerged.
Babies and adults show matching increases and decreases in brain activity when they play together, a 2020 study from Princeton University showed.
In a 2018 study, brain activity was more similar in people who solved a puzzle together than in those who solved the same puzzle separately.
Other studies have shown that brain synchrony between students and teachers is associated with better learning, and that it’s associated with better performance in a group.
Just looking into each other’s eyes may be enough
It may be enough to just look into each other's eyes for brainwaves to start synchronising, according to a study from 2022.
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Perhaps it’s not only human brains that easily fall into sync.
Brain synchronisation has also been observed in bats and mice in social situations, as reported by Science News.
Researchers have also long observed synchronisation in other areas between humans. We tend to walk in step and mirror each other. In some studies, researchers have even seen that people's hearts beat in the same rhythm.
“It seems that our biological systems have a built-in tendency to adapt to the activity of others,” saysSolbakk.
She is a professor at the University of Oslo and a researcher at Oslo University Hospital's neurosurgical department.
Unexpected discovery
Karsten Specht is a professor and brain researcher at the University of Bergen.
He says that shared attention, focusing on the same thing and having a common understanding, seem to be important ingredients for brainwave synchronisation to occur.
“It seems like a very fundamental process that happens automatically without being forced,” he says.
“Was it surprising when researchers started seeing brain synchronisation between people?”
“I would say so. It wasn’t something you would naturally expect. Everyone thinks of each person as individual. Suddenly you see that things are happening between people that you can't actually see, but that can be measured with brain measurement equipment,” he says.
Specht and his colleagues are currently conducting a study in which they are looking at brain activity in people who are talking to each other.
“We went to people's homes, equipped them with a portable brain scanner, and then they were supposed to talk around the kitchen table,” he explains.
“The idea was to look at when synchronisation occurs. Maybe it’s in moments when people understand each other, and maybe the brain falls out of sync when they misunderstand each other?” he adds.
Specht says it’s too early to say anything about the results yet.
What does it mean when brain activity is synchronised?
Brainwaves arise when lots of neurons communicate with each other through small electrical impulses.
They can be seen as oscillations with different frequencies, waves per second, and can be measured with electrodes on the scalp or implanted in the brain.
Researchers can look at whether the waves rise and fall at the same time and how high and low the wave peaks are. Do they increase and decrease simultaneously?
One way to measure synchronisation is to examine whether signals recorded at different electrodes maintain a stable phase relationship over time, says Sigurd Lerkerød Alnes, a postdoctoral researcher at Robert T. Knight's research group at the University of California.
“For example, two cross-country skiers can be synchronised even if one person's poles hit the snow slightly before the other's, as long as the time difference is stable and they ski at the same pace over time,” he says.
The brain measurement methods fNIRS and fMRI do not measure electrical activity but changes in blood oxygen saturation and blood flow in the brain. This makes it possible to see whether this happens in sync in the same areas.
Reason to be critical
Matthias Mittner is a professor of cognitive neuroscience at UiT The Arctic University of Norway.
He finds research on brain synchronisation interesting, but he is also sceptical. The field needs to develop, and what is defined as synchronisation should be standardised, Mittner believes.
There are many possible choices when it comes to measurement methods, analysis, which frequencies the researchers look at, and which brain areas they concentrate on.
This, combined with small sample sizes, makes it easy to find similarities that may actually be due to the researchers' choices and coincidences.
“The theory is also not very precise: It does not specify in advance which brain areas or frequencies should synchronise. As a result, almost any finding can be interpreted as confirmation,” he says.
We try to predict what others will do
What creates the synchronisation?
In addition to shared focus and understanding, something else may play a role: prediction. In other words, anticipating something.
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For example, a tennis player must predict where the ball will land and start moving in advance.
“Predictions are also involved in communication all the time,” says Alejandro Blenkmann, a researcher at the University of Oslo's RITMO Centre.
This is something he has worked extensively on.
We try to predict what the other person will say or do and prepare how we will respond. This can lead to similarities in brain activity when our predictions are correct.
What we expect is constantly updated by new experiences, says Blenkmann.
Matthias Mittner agrees.
“The brain is a prediction machine,” he says.
If it turns out that people who have a high degree of brain synchrony cooperate better or like each other more, this could be explained by prediction.
“When we are able to predict the behaviour of others, the interaction becomes more efficient – we don’t need to use as many resources to process what's happening,” he says.
Does it just come from being in the same environment?
But is it so surprising that there are similarities in brain activity when two people are in the same environment and doing the same thing?
The classic example is that people who play music together have synchronised patterns of brain activity, says Sigurd Lerkerød Alnes.
It could simply be because they listen to the same music and play the same piece of music.
“That doesn’t mean that there is any kind of connection between the people,” says Alejandro Blenkmann.
If synchronisation truly has something to do with contact and communication between people, researchers must control for other factors.
Something more is going on
This is what researchers tried to do in a study that was published last autumn.
In the study, pairs of participants sorted symbols on a screen. Each pair had to decide the rule for how to sort them.
Researchers saw brain synchronisation in the pairs that cooperated, and it increased as the task progressed.
As a test, the researchers used the data they had collected and put together artificial pairs that had chosen the same rule. There was not the same degree of synchronisation between these artificial pairs.
“The study provides good arguments that something more is going on beyond simply focusing on the same thing and being in the same environment,” says Anne-Kristin Solbakk.
Another way to test whether synchronisation plays a role in communication is to use brain stimulation to force brains into sync. Researchers can then see if it has any effect.
In a study from last year, the conclusion was that this kind of stimulation could improve cooperation.
Patients solving tasks together
Anne-Kristin Solbakk, Alejandro Blenkmann, and Sigurd Lerkerød Alnes are working on an international study using hyperscanning.
In the study, brain activity is measured simultaneously in patients in hospitals in different countries. The patients have epilepsy and have had electrodes implanted in their brains to assess treatment for the condition.
In the experiment, the patients collaborate to solve tasks. They take turns describing objects on a screen and guessing which object the other is trying to describe.
“We are investigating how shared representations are established through communication. How do we arrive at a shared understanding of a concept?” says Alnes. “This is the first project that attempts to do something like this.”
Relevant for diagnoses?
In the future, the researchers hope that knowledge about how we create shared understanding can shed light on cases where it doesn’t work. One example could be social difficulties in people with severe autism.
Studies are already starting to appear in which researchers have looked at brain synchronisation in people with diagnoses, according to Anne-Kristin Solbakk.
In a review study published last October, researchers concluded that brain synchronisation appears to be reduced in people with anxiety, depression, and autism.
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Translated by Nancy Bazilchuk
Read the Norwegian version of this article on forskning.no
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