Think carefully before you answer: is a device that is capable of reading people’s minds fact or fantasy? We knew you’d say that. But scientists at an American laboratory have been brainstorming the same question for more than five years and have come up with a mind-blowingly different answer.

They call it Epoc, but when it is launched early next year in Britain and the US it will probably be known simply as the “mind-reading helmet”, capable, supposedly, of knowing what users are thinking.

The device is being hailed as a revolutionary breakthrough in the way that humans will be able to interact with computers. Its implications are massive, opening the possibility that one day people will be able to control everything from light switches to the cursor on their computer screen simply by thinking about it. However, for now, the technology will be used as the ultimate gimmick: to play computer games simply by thinking your screen character into action.

Emotiv Systems, the San Francisco company that has developed the technology, says Project Epoc could mean the end of joysticks and keyboard bashing. Instead games players will be able to visualise a move in their head and that move will be replicated on the screen in front of them. So, for example, Harry Potter could be ordered to cast exotic spells, or a jedi might exert “the force” to fling his enemies around – all through the willpower of the gamer, with no buttons pressed.

The fact that such an advanced system has been developed for something as apparently frivolous as computer games should come as no surprise. The industry is one of the most innovative and competitive, with each company attempting to move a step ahead of its rivals through cutting edge technology (witness the success of the Nintendo Wii, with its wireless controller that reproduces physical movement on the screen and has resulted in a huge sales surge).

The industry is also one of the biggest: sales of computer games and hand-held consoles have exploded over the past five years with some analysts predicting it could soon be “bigger than Hollywood” in terms of turnover. Already in the UK we spend more on computer games than we do on watching films at the cinema. According to Screen Digest, the industry analyst, 2007 will see £1.5 billion being spent on games, compared with £821m spent at the box office.

So how does the helmet work? In simple terms it relies on the fact that every time a human thinks about something, electrical impulses are triggered in the brain. This has been known for years in the medical world and is the basis of an electroencephalogram (EEG) – the technique that measures the electrical activity of the brain by recording from electrodes placed on the scalp.

Emotiv claims to have refined the technique to isolate and identify the electrical patterns that are given off when humans think about a given course of action, such as moving their arm to the left or right or depressing their right thumb or index finger. The Epoc helmet recognises these electrical patterns and translates them into “real” movements on the screen.

To look at, the helmet resembles nothing so much as a novelty head massage gadget with several spidery arms curving around the head and meeting at the top. The arms are fitted with a total of 16 sensors positioned so they are in contact with the relevant part of the head and pick up electric signals in the brain.

The system’s software analyses these signals and then wirelessly relays what it detects to a receiver plugged into the USB port of the game console or PC. Emotiv says it has mapped 12 specific actions that the helmet will recognise and can be reproduced in standard games.

As with handwriting or voice recognition software, the machine has a learning curve, improving as it better understands what the player is thinking. Miming an action can help the helmet wearer visualise the movement they want to recreate onscreen.

“The detection works best when you think about an action in a particular way, repeating that thought pattern,” says Randy Breen, Emotiv’s chief product officer, adding that the device tends to work better with children than adults. “Part of that is because the kid doesn’t have the same kind of barriers as an adult does. Lots of kids can fantasise about moving a cup and believe it.”

But hang on a minute: surely this is all science fiction, Silicon Valley fantasy? To get a clearer idea of what is possible we asked Mark Lythgoe, director of the Centre for Advanced Biomedical Imaging at University College London. Lythgoe, an expert in the science of brain impulses and their detection, says Emotiv’s claims are plausible, up to a point.

He says the idea of neuro-feedback (measuring the electrical impulses of the brain and mapping them to specific actions) is already used to reteach patients how to use their brain after an accident. “You can put somebody in a brain scanner and ask them to think ‘I want to move my hand’ and the screen will light up showing the relevant part of their brain,” he says. “It sounds like this [Emotiv’s] technology is trying to do the same job.” So far so good. By detecting electrical impulses, the helmet can be trained to cause a character on the computer screen to echo certain actions of the wearer, such as winking or moving its arms.

However, Lythgoe is cautious about Emotiv’s claims to be able to translate thoughts alone – rather than thoughts and movements – into computer commands. “Although I think this device can apparently do the things that it claims, I wonder if it works in the way that it says it does.”

The helmet, he says, may be detecting the larger electrical activity – not from the brain alone – but from similar impulses created by muscle movements. In other words, a subject thinking of moving a character on a computer screen may be making tiny involuntary movements, small twitches might be enough, that the helmet is picking up.

“EEG-type devices are highly sensitive to picking up changes in, say, the muscles of the face, such as a wink or a smile,” says Lythgoe. This is because electrical signals created within the brain are amplified by movements in the body.

“For a scanner to detect pure thoughts is possible and based on real science. But it is extremely hard, especially once the person wearing the headset starts to move. The larger signals caused by movement would drown out the thought signals. It would be like hearing whispers in a disco. If this has been achieved it is awesome; a real breakthrough.”

Emotiv maintains that what its device is detecting is brain signals, not just the echoes of physical movement. Furthermore, it says, it has made breakthroughs in the processing of those signals. Each person’s brainwaves have a unique pattern, which is why it is so hard to interpret them.

Software built into the headset can unfold these patterns and make the signal far easier to interpret. “At the core of this is our ability to extract meaning from the signals, not simply to detect them with greater sensitivity,” says Tan Le, president of the company.

If true, the implications are huge. Emotiv believes gaming is merely the way to popularise the technology rather than being an end in itself: the tip of the virtual iceberg. In the long run the headset could have a huge range of applications, from the use of brain scanners as lie detectors to see whether suspects recognise a crime scene, to enabling consumers to turn machines on or off or change television channels without a remote control.

Le even claims her researchers have developed the machine to a point where it can detect people’s moods and emotions and speculates that in time this will enable an iPod, for example, to select a tune that corresponds to the user’s state of mind.

This proves the final straw for Lythgoe. “I’d chuck out my department’s brain scanner tomorrow if this company has developed one that can genuinely pick up emotions,” he says.