On the same wavelength
The chemistry is good. Two people get along immediately, complement each other, and quickly find solutions together. What many of us know from everyday life can also be observed in the brain: when two people interact, certain patterns of their brain activity fall into alignment - a process that researchers refer to as neural synchrony. It occurs when people talk to each other, look at something together, or tackle the same task. According to studies, the higher the synchrony between the brains of individuals, the more successfully will they collaborate. They learn better from one another, complete tasks more efficiently, and feel more connected.
Can synchrony be controlled?
Studies show that as early as in the first years of life, the brains of toddlers and their caregivers synchronize. But can this synchrony be induced at will? This is the topic of Kathrin Kostorz’s research at the Faculty of Psychology at the University of Vienna. In the context of a project funded by the Austrian Science Fund FWF, Kostorz is developing a method that allows two people to receive real-time feedback on their mutual brain activity. The goal is to explore whether people can learn to consciously synchronize their brain signals and, if so, whether this improves their collaboration. In the future, the method could be used with individuals having psychiatric disorders that put a strain on their social interactions and lead to relationship problems.
“In principle, synchronization means that brain signals become more alike, which is usually the case as soon as we interact with one another,” explains Kostorz. In the context of her doctoral research she had already discovered that this similarity can be linked to better learning. Test subjects watched a video of a person folding origami figures. The result: when the test subjects’ brain signals showed more similarity to those of the demonstrator, they performed better at the art of Japanese paper folding. Other studies have found similar correlations. In the classroom, students learned more successfully when their brain activity was more synchronized with that of the teacher.
Syncing Brains
When two people interact, their brain activity can become synchronized. This project investigates whether specialized neurofeedback techniques can help improve interpersonal interaction.
Great minds think alike
This gave rise to a new idea: what if people didn’t just synchronize unconsciously, but actively induced this process? For her investigations Kostorz draws on the established approach of neurofeedback and is developing a new method called hyperfeedback.
In neurofeedback, people receive information about their own brain activity. A sensor cap worn on the head records the signals, and a computer translates them into a screen image that laypeople can understand. For instance, the screen could show them the image of a thermometer that they are meant to influence. Over the course of several training sessions, they learn to deliberately trigger specific activity patterns in the brain – for example, by trying to move the thermometer’s slider upward – without pressing any buttons and using only mind power.
A much debated research question
Kostorz now wants to explore whether this can be taken a step further: can two people actively synchronize their brain signals to “the same wavelength”? As Kostorz explains, this is a “hotly debated topic” in research. Studies on brain synchronization are currently being published at an increasing rate. The topic is fashionable. But it’s difficult to control, involves many pitfalls, and involves very complicated technical setups. “I didn’t expect to have to spend so much time on fine-tuning the signal processing,” Kostorz notes. “Tomorrow I’ll go back to the basement and wonder: why on earth aren’t my devices communicating with each other again?” Apart from the passionate debates among researchers, Kostorz is primarily interested in one other question: “Why are we more in sync when we get along better?”
Kostorz hopes that the findings of her research project will enable her to develop recommendations and an overview of the complex background and obstacles involved in such an analysis. One initial success has already been achieved: the measurements are, in principle, possible. On the down side, they take significantly longer than expected. A brainwave measurement must last about one minute before test subjects are presented with this activity. Is that too long? That will become clear by the end of the project, when the entire process is tested on healthy volunteers.
The foundations have been laid
Kostorz relies on a measurement technique known as functional near-infrared spectroscopy, or fNIRS for short. This is a non-invasive, portable imaging method for measuring brain activity. Unlike large magnetic resonance imaging (MRI) scanners, the technology is mobile and less costly. Test subjects can move around and do not have to lie still in a narrow tube. This could be particularly helpful for testing children. Because children’s skulls are thinner, their brain signals can be detected particularly well. The system tracks which brain regions are consuming a particularly large amount of oxygen at a given moment, thereby providing an indirect measure of activity. Kostorz hopes that this approach could save costs and make it easier to test children “who, by nature, have a hard time sitting still”.
The new neurofeedback application opens up fresh possibilities, for instance in learning contexts or therapeutic settings. It’s conceivable that patients with difficulties in social situations could learn to tune in more closely to the person they’re interacting with. “But this isn’t a one-way street. Even therapists could use it to develop a better understanding of the people they’re working with,” notes Kostorz. There are many options. “Given that we have now clarified the prerequisites, it is fundamentally feasible.”
About the researcher
Kathrin Kostorz conducts research at the Institute for Psychology of Cognition, Emotion, and Methods at the University of Vienna. She studied physics and systemic neuroscience at the Technical University of Munich and Ludwig Maximilian University of Munich (LMU). As part of her doctoral research, she investigated the neural mechanisms of observational learning between teachers and students in the context of acquiring new skills. Currently, her research focuses on measurements of neural synchrony, neurofeedback, and hyperscanning with the help of the imaging techniques fMRI (functional magnetic resonance imaging) and fNIRS (functional near-infrared spectroscopy). Set to run until September 2026, the project “Hyperfeedback: Syncing brains to improve human interaction” has been awarded approx. EUR 294,000 in funding by the Austrian Science Fund FWF.
Publication
Investigating short windows of interbrain synchrony: A step toward fNIRS-based hyperfeedback, in: Imaging Neuroscience 2025
