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Researchers Mind-Melded Three People to Collaboratively Play 'Tetris'

This is the first time that a brain-to-brain interface has incorporated more than two people.
A man hooked up to an EEG machine, similar to the ones used in this experiment. Image: Wikipedia

Why text or call someone when you can just beam your thoughts directly into their brain? It may sound like an episode of Black Mirror—and we’re not quite there yet—but scientists are able to manifest a simplified version of this, and they recently achieved it with more than two people for the first time.

Brain-to-brain interface uses modern brain scanning tools to allow people to communicate, in a sense, telepathically. In a paper posted to the arXiv preprint server last week, researchers from the University of Washington detailed a new example of this technology using three people for the first time, creating what they describe as a brain-to-brain “social network.”


The way the participants can interact is very limited at this point, but it shows the potential for this kind of wordless communication for group decision making in the future.

Here’s how it works: the researchers used groups of three people, two “senders” and one “receiver,” all in separate rooms. All three participants are hooked up to an electroencephalogram (EEG) device, which records electrical activity in the brain. The “receiver” is also hooked up to a machine that provides transcranial magnetic stimulation (TMS), which stimulates certain reactions in the brain using short bursts of targeted magnetic energy.

In the experiment, the teams of three were tasked with playing a kind of ultra-simple game of Tetris. The two senders could see the whole screen, while the receiver could only see pieces as they fell, and not the bottom where they would land. To win the game, the two senders would have to indicate to the receiver whether or not to rotate the piece so that it would fit into the slot:

An example of the screen from the senders' perspectives. Image: arXiv

This is where the telepathy happens: if the sender wanted the receiver to rotate the piece, he or she would focus their eyes on the right-hand side of the screen, where an LED light flashed at 15 Hz. This generates brain waves at the same frequency, which the EEG would pick up and transmit to the receiver’s TMS. That signal would then cause the TMS to induce a spot of light to appear in the receiver’s field of vision, which was code for “rotate the block.” The receiver would then have to interpret the cues from the two independent senders and decide what to do.

The screen that senders would use to decide which message to transmit to the receiver. Image: arXiv

Using this technique, groups of three were able to complete the Tetris puzzle with an average accuracy of 81.25 percent, according to the paper. That sounds more accurate than if you had your friend shout “Turn it! Turn it!” over your shoulder at the arcade. And this was in spite of the fact that, for some trials, the researchers would purposely interfere and make one of the senders send the wrong instruction, so that the receiver would have to figure out which sender was more often right, and which one was messing with them.

This isn’t the first time researchers have been able to allow people to communicate in a brain-to-brain interface. Previous experiments have allowed researchers to create an “organic computer” by wiring four mice brains together, shown that people can successfully complete a game of 20 questions via brain-to-brain transmission, and have monkeys collaboratively control a 3D arm model using only their thoughts.

“Using only the information delivered by BrainNet, receivers are able to learn to differentiate the reliability of information conveyed to their brains by other subjects and choose the more credible sender,” the paper explains. “This makes the information exchange mediated by BrainNet similar to real-life social communication, bringing us a step closer to a ‘social network of brains.’”