Image caption Human-to-human "mind control" has, until now, been a concept in science fiction and fantasy

With one tap on his space bar, Andrea Stocco fires the cannon on his computer game and blows a rocket out of the sky.

The game itself is unremarkable - in fact it looks like a relic of the 1980s.

What is remarkable is the way it is being played because the University of Washington researcher can't actually see it.

The person who can, fellow scientist Rajesh Rao, is sitting across campus looking at the screen.

He is wearing a cap with wires coming out of it (which looks like something you might have seen in a 1950s sci-fi programme that was imagining this moment).

Without moving a muscle, or using a communication device, Mr Rao told his colleague to fire the cannon at just the right moment.

The only thing Mr Rao had was the power of his mind, so, at the right moment, he imagined firing the cannon.

This sent a signal via the internet to Mr Stocco, who, wearing noise-cancelling earphones (and a purple swimming cap) involuntarily moved his right index finger to push the space bar.

Imperius curse

What has just happened seems to be the first documented case of human-to-human "mind control".

The researchers gave it the rather less alluring title of human-to-human brain interface, but that's scientists for you.

Image caption University of Washington researcher Rajesh Rao, left, plays a computer game with his mind. Across campus, researcher Andrea Stocco, right, carries out the command

Until now this concept remained in the realms of theory, or more likely science fiction and fantasy.

Those of a wizarding persuasion will see parallels with the evil Voldemort's Imperius curse, used to manipulate people in the Harry Potter stories.

It could lead to better-linked teams of people - who may speak different languages - working together to solve hard problems faster Daniel Wilson, Robopocalypse author

Mr Stocco jokingly refers to the experiment as a "Vulcan mind meld", after a technique employed by Mr Spock in Star Trek to share thoughts.

"The internet was a way to connect computers, and now it can be a way to connect brains," Mr Stocco says.

He compares the feeling of his hand moving to that of a nervous tic.

Mr Rao says it was "both exciting and eerie" to watch an imagined action from his brain get translated into actual action by another brain.

"The next step is having a more equitable two-way conversation directly between the two brains," he adds.

Brain activity

There are already numerous examples of the human brain being used to control technology.

For example, Samsung is experimenting with a mind-control tablet.

Technology firm Interaxon is marketing a "brain sensing headband" that it hopes will allow people to control devices with their minds.

It is already widely used to help those with physical disabilities.

Indeed the technology for recording and stimulating the two researchers' brains in this experiment are both well-known.

Image caption Brain signals from the "Sender" are recorded. When the computer detects imagined hand movements, a "fire" command is transmitted over the internet, causing an upward movement of the hand of the "Receiver"

Electroencephalography - the technique used to send the message from Mr Rao - is routinely used by the medical profession to record brain activity from the scalp.

Transcranial magnetic stimulation - which made Mr Stocco's finger move - is a way of delivering stimulation to the brain to prompt a response.

But putting the two together, effectively allowing one person to direct the responses of another, is new.

'Trivial'

The researchers are quick to point out that this experiment is very basic in terms of the concept.

But Daniel Wilson, who has a PhD in robotics and is the author of Robopocalypse, says it remains important as a "proof of concept" experiment.

There's no possible way the technology that we have could be used on a person unknowingly or without their willing participation Chantal Prat, University of Washington

"It has sparked a discussion of how brain-to-brain interfaces might impact society in the future," he says.

"Although the experimental set-up is too narrow to have practical value, it certainly makes us think."

However, others are unimpressed.

Dr Ian Pearson, a futurologist with a background in science and engineering, compares it to experiments by Australian performance artist Stelarc 15 years ago.

He enabled people to remote control his limbs via the internet.

"Adding a simple thought recognition control system is pretty trivial," Dr Pearson says.

"If they were taking a thought from one person and directly creating a thought in another then I'd be impressed."

Collaboration

There is more general agreement on the impact that future developments in this field could have on the way humans collaborate and communicate.

Mr Stocco says that one day it could be used to enable someone on the ground to help a passenger land an aeroplane if the pilot becomes incapacitated.

Image caption "Are you thinking what I'm thinking?" Star Trek character Mr Spock used the "mind meld" to share thoughts

Dr Pearson cites the example of a complex project where numerous different types of professionals are involved.

"Say you're trying to design a building and you have engineers, designers and artists," he says.

"Even if they are far apart, the artist could conjure up an idea and perhaps the engineer thinks that won't work for some reason, so they refine it.

"Working together they could come up with something complex, very quickly."

Dr Pearson, who gazes in to the future for a living, is pretty sure this scenario will one day be real, based on nano-technology placed directly onto the brain.

When we have full links into the brain directly and you can control someone like a robot then we might have problems Dr Ian Pearson, Futurologist

But we'll have to wait another 30 to 40 years for that, he says.

No zombies

Of course, the whole concept of mind control is often overshadowed by the disturbing implications of its misuse.

Although he has written a book about a dystopian, robot-controlled future, Mr Wilson is sanguine about the implications of the experiment.

"I see nothing inherently dangerous about increasing the communication bandwidth between human beings," he says.

"If anything, it could lead to better-linked teams of people - who may speak different languages - working together to solve hard problems faster.

"The intricate technical requirements of transcranial magnetic stimulation make covert mind control unfeasible."

Chantal Prat is assistant professor in psychology at the University of Washington and helped conduct the experiment.

She agrees with Mr Wilson's analysis.

Image caption Dr Pearson believes these techniques will be used in the future by teams carrying out complex tasks

"I think some people will be unnerved by this because they will overestimate the technology," she says.

"There's no possible way the technology that we have could be used on a person unknowingly or without their willing participation."

Just beware of someone coming at you holding a swimming cap with wires poking out of it.

But these are early days; what will come as the technology develops is anyone's guess.

"We are not in the realms of creating zombies," Dr Pearson says.

"When we have full links into the brain directly and you can control someone like a robot then we might have problems.

"Whether it turns to slavery or state control - who knows; you could write any number of sci-fi books about that."