Playing Tetris using the mind

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We will never have enough of searching for new ways to improve the gameplay experience and make it as immersive as possible. Scientists seem to had found a slit to pass through and achieve this, but the way to go is still long if we imagine the latest generation videogames played with our mind. But what about old games, like Tetris?

The University of Washington together with Carnegie Mellon University have developed BrainNet, a BCI system that allows three people to communicate with one another using brain waves.

BrainNet

The interface developed by the team combines electroencephalography, to record brain signals, with transcranial magnetic stimulation to deliver information to the brain, noninvasively. Interfaces like this already existed, but the team moved a step forward by allowing up to three human subjects to collaborate and solve tasks.

Heather Wessel, Theodros Haile and Savannah Cassis communicating using BrainNet. Credits: Mark Stone/ University of Washington
Heather Wessel, Theodros Haile and Savannah Cassis communicating using BrainNet. Credits: Mark Stone/ University of Washington

This kind of system, also known as BBI – brain to brain interface -, allows direct communication between brains. It is considered a next-generation BBI, thanks to his capability of communication without physical action. Before, indeed, there was a need for a concrete action by one of the subjects to proceed through certain steps. We can bring as an example the BBI “20 Questions”, that allowed a Receiver to choose a question (by touching the screen) and let a Sender select the answer with just his brain. Also, earlier versions of this system allowed only two subjects to communicate.

BrainNet allows the existence of two Senders and one Receiver but can be scaled up to a large number of Senders. The role of the Senders is to observe the state of the task and convey its decision to the Receiver. This subject then has to integrate these decisions and choose what to do, using his mind. Also, the new interface supports two rounds of interactions: the first decision made by the Receiver is perceived back by the Senders, who can convey corrective decisions back to him. Last but not least, the Receiver uses both TMS and EEG, completely eliminating any physical movement.

BrainNet Architecture. Credits: nature.com
BrainNet Architecture. Credits: nature.com

To communicate (the Senders) and to execute an action (the Receiver) BCI are used, and also to see the results on the screen. These BCIs are based on EEG. Once a Sender takes a decision, a CBI (Computer-Brain-Interface) transmits information over the network, to the Receiver. Here, another CBI linked with TMS gives the information to the Receiver, who consciously processes the input from the Senders and executes an action in the task. The Senders can then see the result on their screens, and act consequently in the second round.

Tetris becoming a “mind-game”

To test BrainNet the team chose Tetris. In each of the trials a participant, the Receiver, was in charge of deciding whether or not rotate a block before it drops at the bottom of the screen. The hard part was that this subject couldn’t see the bottom part, and could only rely on the information of the other two participants. These two, on the contrary, could see the entire screen and had to make the right decision (rotate or not).

TMS pulses deliver Senders’ decisions sequentially to the occipital cortex, eliciting a phosphene if it’s yes, or not eliciting it if it’s no. This is the first round. After this, Senders can examine the Receiver’s decision and give new (corrective) decisions.

The Tetris screen seen by Receiver (left) and Senders. The first subject can't see the bottom line of the screen, making him rely on Senders. Credits: BrainNet
The Tetris screen seen by Receiver (left) and Senders. The first subject can’t see the bottom line of the screen, making him rely on Senders. Credits: BrainNet

Tests were conducted on five triads of participants, and each one of them performed 16 trials. Results showed an accuracy of 81.25%. As the simplest measure of overall performance, the proportion of correct block rotations showed an higher-than-expected outcome. The mean accuracy across the triads was of 13 correct trials out of 16. Giving 0.5 as theoretical chance accuracy, the results were incredible and promising.

Graphic of overall accuracy of BrainNet. Credits: BrainNet
Graphic of overall accuracy of BrainNet. Credits: BrainNet

As the first multi-person, non-invasive direct brain-to-brain interface, BrainNet is successful and a starting point for future collaborative BCIs. Supported by sufficient and adequate hardware, it can scale up to multiple subjects and to cases where each participant can be both a Sender and a Receiver.


 Sources

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Marina Londeihttps://systemscue.it
I'm an enthusiast of and passionate about the world of programming and computer science, with Master Degree in informatic engineering.

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