(CNN) -- Every so often, you see something that makes you think: The future is here.
Researchers at the University of Washington have demonstrated what they say is the first example of a noninvasive human-to-human brain interface. In a video posted online, they show how a scientist could control another scientist's hand motions just by using brain signals sent over the Internet.
The two participants in this demonstration were the scientists themselves, Rajesh Rao and Andrea Stocco. They were situated on different parts of the University of Washington's campus when Stocco's finger moved on a keyboard, controlled by Rao's brain signal.
An ethical review board gave the two of them specifically -- and no one else -- permission to try it out, Stocco said.
"So far, we are the only human beings whose brains are being connected," said Stocco, a research assistant professor at the university's Institute for Learning and Brain Sciences.
They have now done several trials of this brain communication in their unpublished pilot study and hope to expand it.
How they did it
Rao wore a cap with electrodes that were connected to an electroencephalography machine, a contraption that reads electrical activity from the brain. Rao played a video game without using his hands, just using his mind. By imagining moving his right hand, he could move a cursor on the computer screen to click "fire," in order to fire a cannon at a target. The goal of the game is to hit rockets fired by pirate ships and avoid hitting supply planes.
Meanwhile, in Stocco's lab across campus, Stocco wore a purple swim cap. A transcranial magnetic stimulation coil was placed over his left motor cortex, the part of the brain that controls hand movement.
The electrical activity of Rao's brain was read by the electroencephalography machine, which then sent signals over the Internet to Stocco's brain by way of the transcranial magnetic stimulation coil. The signal activated the neurons that prompted Stocco's right hand to move.
Because of this connection, Rao's thinking about moving the cursor almost simultaneously caused Stocco to press the space bar of his own keyboard with his right index finger.
The first time, says Stocco, "I didn't know precisely if my hand moved because actually I got the signal from the machine or if I was twitching."
"I never twitch, so I was pretty sure that it was the signal, so I felt happy."
This all sounds futuristic and spacey. But wait -- this isn't published in a peer-reviewed journal, which is the gold standard for scientific results, says Dr. Miguel Nicolelis, professor of neuroscience at Duke University, who has pioneered brain-computer and brain-brain interface techniques.
Stocco said he and Rao plan on submitting their results to journals, but wanted to get the word out quickly after they had evidence of their success.
What's more, Nicolelis says, Stocco was not consciously interpreting the signal from Rao. Instead, the brain signal caused Stocco's finger to move involuntarily.
The absence of choice in this situation makes it less impressive from a scientific standpoint, Nicolelis said. The same effect could have been achieved by a cell phone or a computer triggering the involuntarily movement.
"It's like a technical trick, but it doesn't cross the threshold of brain-to-brain communication," he said.
What came before
Harvard University researchers have also shown that a human could move a rat's tail with their minds, translating the person's neural signals to excite the motor area of a rat that had a motor sensor on it. This study was published in the journal PLOS One earlier this year.
A true brain-to-brain interface would involve the ability for choice, and for feedback, Nicolelis said. In other words, the receiver would have the ability to send signals back to the sender.
Nicolelis' own research has shown this more complicated technique is possible, at least in rodents. In an experiment described in a study in the journal Scientific Reports, two rats were placed in separate chambers with several levers. The brains of these rats were connected through arrays of tiny electrodes. One rat got a visual cue about which lever would lead to a reward of a drink of water. When this rat pressed the correct lever, the second rat received brain activity from the first rat corresponding to that decision.
The researchers believe that the receiving rats were actively using and interpreting this information, not just pressing a lever involuntarily, because the receiving rat pressed the correct lever about 70% of the time. That is still fairly high, but not 100%.
Here's the more impressive part: The rats appeared to demonstrate two-way collaboration in their brain network -- the rat sending the signal changed its brain function and behavior when the receiving rat did not press the correct lever. The researchers incentivized this by not giving a full reward to the sending rat if the receiving rat messed up.
This kind of two-way brain communication between humans has yet to be demonstrated. But that doesn't mean it isn't possible.
For now, the University of Washington scientists can show off their technique using simple brain signals, but their technology doesn't allow people to read each other's thoughts.
And don't worry -- it was done in a laboratory setting in accordance with a strict human-testing protocol, so it would not be used to control people's behavior without their consent, they say.
The technology is still in its early stages, but Stocco imagines many practical applications: For instance, a senior surgeon could control the hands of another surgeon in training during an operation. Stocco also told the University of Washington's news office that a person with disabilities could signal that he or she would like food or water, or a pilot who becomes incapacitated could be assisted from the ground.
"It was both exciting and eerie to watch an imagined action from my brain get translated into actual action by another brain," Rao told the University of Washington's news office. "This was basically a one-way flow of information from my brain to his. The next step is having a more equitable two-way conversation directly between the two brains."
The researchers said they intend to conduct another experiment involving more complex information from one brain to another. They will try the technique on more people if that is successful, and if approved by the ethics board.
If they can pump up the technology to do what Nicolelis has demonstrated in rats, this would be, quite literally, a meeting of minds.