Linking Two Brains for a Game

What if you knew what someone was saying without them opening their mouth?

Located in different buildings on the Univ. of Washington’s campus, approximately one mile apart, two human test subjects sat in front screens. Over the Internet, they played a game akin to 20 questions, but no oral communication was involved. Instead, the inquirer selected questions from the screen. Respondents, outfitted in an electroencephalography cap, answered the yes or no question by fixing their eyes on flashing LED lights situated on the sides of the monitor. Transmitted back to the inquirer, the answer activated a magnetic coil situated behind the inquirer’s head, stimulating the visual cortex. The intensity of the burst of light, known as a phosphene, indicated whether the respondent’s answer was yes or no. 

“This is the most complex brain-to-brain experiment, I think, that’s been done to date in humans,” said lead author Andrea Stocco, an assistant professor of psychology at the university’s Institute for Learning & Brain Sciences. “It uses conscious experiences through signals that are experienced visually, and it requires two people to collaborate.”

Univ. of Washington researchers found participants in the game successfully guessed the selected objects 72% of the time. The experiment and results are detailed in PLOS One.

Five pairs of study participants played 20 games each, with 10 real games and 10 control games. During control rounds, the phosphene signals were interrupted, unbeknownst to the participants. Control rounds yielded 18% accuracy.

During games, the object was randomly selected by a software program; presented to the respondent, but hidden from the inquirer. “The inquirer was instead shown a list of possible objects on the right side of the computer screen and an associated list of questions on the left side,” the researchers write.

However, the experiment was not without limitations. Even though a majority of the real games were successful, the researchers contend verbal communication, most likely, would have been more efficient.

Some uncertainty may have also arisen due to the nature of phosphenes. “They have to interpret something they’re seeing with their brains,” said co-author Chantel Prat, of the university’s Institute for Learning & Brain Sciences. “It’s not something they’ve ever seen before.”

A $1 million grant from the W.M. Keck Foundation funded the research. The researchers are exploring various ways to decode complex brain processes and interactions. Possibilities being explored include transferring knowledge directly from a teacher’s brain to a student’s brain.

“Evolution has spent a colossal amount of time to find ways for us and other animals to take information out of our brains and communicate it to other animals in the forms of behavior, speech and so on,” said Stocco. “But it requires a translation. We can only communicate part of whatever our brain processes.”