Scientists play Twenty Questions by reading each other's MINDS: Answers were sent more than a mile using brain signals It is a breakthrough that could pave the way for soldiers being able to read each other's thoughts on the battlefield or pupils learning their lesson without their teacher having to speak a single word.

A telepathic version of the game Twenty Questions has been played by two people a mile apart.

The US experiment into mind reading involved using electrode caps, magnetic coils and the internet to send brain signals between two people.

It begun with the first person, who was wearing a cap studded with electrodes that recorded their brain activity, thinking of an object.

Their opponent sent them a series of questions over the internet in an attempt to guess what they were thinking of.

The first player answered 'yes' or 'no' to each question by looking at one of two flashing lights attached to their computer screen.

This created a signal that was transmitted electronically, activating a magnetic coil by the second player's head.

Crucially, only the 'yes' signal was strong enough to fool their brain into seeing a flash of light.

Just as in the traditional version of Twenty Questions, the combination of 'yeses' and 'nos' allowed the second player to guess what the first one was thinking of.

Five pairs played the game and they got the answer right 72 per cent of the time - significantly more than by chance.

Lead author Andrea Stocco, of the University of Washington, said: 'This is the most complex brain-to-brain experiment, I think, that has been done to date in humans.'

Co-author Chantel Prat said: 'They have to interpret something with their brains they have never seen before.'

Writing in the journal Plos One, the researchers say they are now researching 'brain tutoring' “ transferring signals directly from teacher to pupil or from the brain of a healthy person to a stroke patient.

Other possibilities include transmitting a sense of alertness to a sleepy person.

The research follows on from a recent study in which scientists sent a ˜mental message™ from one person to another 4,000 miles away. 

They connected one person in Mumbai, India, to a wireless headset linked to the internet, and another person to a similar device in Paris.

When the first person merely thought of a greeting such as ˜ciao™, Italian for ˜hello™, the recipient in France was aware of the thought occurring, according to a report in the journal Plos One.