Researchers from the University of Washington successfully sent thoughts over the Internet in an unprecedented mind-reading experiment that shows two brains can be linked directly to allow one person to accurately guess what is on the other person's mind.

For the experiment published in PLOS ONE on Wednesday, volunteers played a game similar to "20 Questions," wherein one player thinks of an object and the other player attempts to guess what it is with a series of questions that the first player then answers with either a "yes" or a "no."

What makes this version of the game different is that the pair of participants played from different locations. One of the participants - the "respondent" - located a mile away was outfitted with a cap connected to an electroencephalograph (EEG), which picks up signals from the brain and records brain activity.

The other participant - the "inquirer" - was also outfitted with a cap with a magnetic coil placed behind the area of the brain controlling the visual cortex, which processes visual information.

The respondent is shown an object that the inquirer would guess by asking questions. The inquirer is given a list of questions to ask the respondent. After receiving a question, the respondent answers by looking at one of two flashing LED lights mounted on the monitor. The light for "yes" flashes at a different frequency than the light for "no." The respondent would then signal the inquirer whether the answer was a "yes" or a "no" by focusing on one flashing LED light.

Both "yes" and "no" answers send a signal to the inquirer and activate the magnetic coil, but only "yes" can generate an intense-enough response to stimulate the inquirer's visual cortex. If the answer is "yes," the inquirer will see lines, blobs or spots of light called "phosphenes," indicating the affirmative response. There are no corresponding phosphenes with "no" answers.

The participants managed to guess the correct object in 72 percent of the games with the method. In contrast, they were able to get the answer correctly 18 percent of the time when they guessed by chance.

"This is the most complex brain-to-brain experiment, I think, that's been done to date in humans," said study author Andrea Stocco from the Institute for Learning and Brain Sciences at the University of Washington. "It uses conscious experiences through signals that are experienced visually, and it requires two people to collaborate."

The researchers said that the melding of two minds has potentials for a range of applications such as enabling the transfer of information from a healthy brain to an impaired one. It may also allow an alert person to transmit his brain state to someone who struggles to pay attention.

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