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Mind Meld: Tetris Players Electronically Connect Their Brains

Humans collaborate using brain-to-brain communication to play video game

4 min read

3 combined photographs of users of the BrainNet, a multi-person non-invasive direct brain-to- brain interface for collaborative problem solving.
Photos: University of Washington

Have you ever felt a strong emotion, such as elation from taking in a scenic view, and wanted to share it with the people around you? Not “share” as in tell them about it or post it on social media, but actually share it—like beam the feeling from your brain into theirs?

Researchers at the University of Washington in Seattle say they would like to give humans that kind of brain-to-brain interaction, and have demonstrated a baby step toward that goal. In a set of experiments described in the journal Scientific Reports, the researchers enabled small groups of people to communicate collaboratively using only their minds.

In the experiments, participants played a Tetris-like video game. They worked in groups of three to decide whether to rotate a digital shape as it fell toward rows of blocks at the bottom of the screen. 

The participants could not see, hear, or communicate with each other in any way other than through thinking. Their thoughts—electrical signals in the brain—were read using electroencephalography (EEG) and delivered using transcranial magnetic stimulation (TMS).

The messages sent between participants’ brains were limited to “yes” and “no”. But the researchers who developed the system hope to expand upon it to enable the sharing of more complex information or even emotions. “Imagine if you could make a person feel something,” says Andrea Stocco, an assistant professor at the University of Washington, who collaborated on the experiments.

We already try to elicit emotions from each other—to varying degrees of success—using touch, words, pictures and drugs. And brain stimulation techniques such as TMS have for more than a decade been used to treat psychiatric disorders such as depression. Sharing emotions using brain-to-brain interaction is an extension of these existing practices, Stocco says. “It might sound creepy, but it’s important,” he says.

Stocco’s experiments with the technology, called brain-to-brain interface, or BBI, are the first demonstration of BBI between more than two people, he and his colleagues say. 

Examples of Screens seen by the Receiver and the Senders across Two Rounds. Te Receiver sees the three example screens on the lef side and the Senders see the screens on the right side.Examples of screens seen by the receiver and the senders across two rounds. The receiver sees the three example screens on the left side and the senders see the screens on the right side.Image: University of Washington

To be accurate, the technology should probably be called brain-to-computer-to-computer-to-brain interface. The brain signals of one person are recorded with EEG and decoded for their meaning (computer number one). The message is then re-coded and sent to a TMS device (computer number two), which delivers electrical stimulation to the brain of the recipient.

In Stocco’s experiments, this chain of communication has to happen in the amount of time it takes a Tetris-style block to drop (about 30 seconds—it’s slow Tetris). Participants work in groups of three: two senders and one receiver. The senders watch the video game and each decide whether to rotate the block or not. Then they send their yes or no decision to the receiver, who sits in a different room, and is charged with taking action to rotate the block or not, based on the senders’ messages. (Receivers can only see half the game—the piece that is falling—and not the rows of blocks into which the piece is supposed to fit, so they depend on the senders’ advice.) 

If senders want to rotate the block, they focus their attention on an area of their screen that says “yes” with an LED flashing beneath it at 17 hertz. If they do not want to rotate it, they focus their attention on area of the screen that says “no” with an LED flashing beneath it at 15 hertz. 

The difference in brain activity caused by looking at these two different rates of flashing light is fairly easy to detect with EEG, says Stocco. A computer then evaluates the brainwave patterns, determines if they corresponded with yes or no, and sends that information to the third person in the group (the receiver). 

The receiver wears a TMS device that induces gentle, electrical stimulation in the brain non-invasively. If the message from a sender is “yes” the TMS device stimulates the receiver’s brain in a way that produces some kind of visual cue, such as a flash of color. If the message is no, the receiver gets no visual cue. Messages to the receiver from the two senders arrived one after the other, in the same order each time.

experiment set up photoPlayer’s thoughts were read using electroencephalography and delivered using transcranial magnetic stimulation.Photo: University of Washington

To make things interesting, the researchers asked one of the two senders to frequently transmit the wrong answer. All the receivers noticed the pattern of bad advice, and chose to listen to the more accurate sender. 

Compared with the complexity of human thought, this binary form of brain-to-brain communication is just one step toward something that might be useful outside the lab. No emotions were shared between participants, aside from perhaps a little nostalgia among the participants who grew up with the real Tetris. 

To reach a higher level of sophistication in brain-to-brain communication, researchers will likely need equipment that can read brain activity with more spatial resolution than EEG, and can stimulate with more specificity than TMS. For this, some BBI researchers are turning to fMRI and ultrasound, Stocco says.

BBI work is slow going. Stocco and his University of Washington colleague Rajesh Rao first demonstrated a form of BBI in 2013. Other groups followed on shortly after. Now, six years later, researchers working on the technology are only inches from where they started. “There are maybe four or five groups working on this globally, so we get maybe one paper a year,” says Stocco. 

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