Many people have eagerly awaited the day they can control technology using just their brains. Companies like Emotiv Systems, Neurosky, and Interaxon, some of which showcased this year at CES, manufacture headsets that claim to do just that. Breathless articles have gushed about video games and even cars controlled only by a person’s mind. But this isn’t quite mind control — at least, no one’s controlling tech with just their thoughts.

These headsets sense the electrical activity inside a person’s brain using a technique known as electroencephalography, or EEG. The technique works like this: Electrodes are placed on the surface of someone’s head; these electrodes can measure the electrical signals produced by the brain's neurons through the scalp. EEG has been used as a diagnostic tool for more than half a century. Neurologists can identify patterns in a patient's brain wave activity, allowing them to spot abnormalities that could give rise to seizures or other neurological disorders.

Commercial EEG headsets are more like gimmicks

It's only recently that people have started harnessing EEG as a way to control technology and devices. EEG has been used to help amputees control high-tech prosthetic limbs. Patients with spinal cord injuries or ALS could potentially use the technology to mobilize their wheelchairs or better communicate. Commercially, EEG headsets claim to give wearers something akin to super powers; headlines exuberantly proclaim things like "The Video Game Helmet That Can Hack Your Brain" or "Brainwave-reading headset lets you control your TV with your mind." As more wearable technologies emerge that claim to quantify our biology, it’s only expected that devices would be created to tap into our brains. But these commercial EEG headsets are more like gimmicks.

Take Emotiv Systems, which makes an EEG headset called Epoc. Though Epoc has been used to control video game avatars, motorized skateboards, and cars, the headset isn’t marketed for any specific task. Emotiv says the device is more for enabling research in the fields of neuropathy, entertainment, and marketing. The controls work like this, according to Emotiv: users can "train" Epoc by thinking of certain objects or motions over and over; this allows the EEG to pick up the patterns associated with each thought. "You can think 'fly' or think about something that you can recall with clarity," says Kim Du, a spokesperson for Emotiv. "You can think about pushing, think about the color blue. The software program is looking for that specific pattern."

Brain patterns can be used to control video game avatars

Those patterns can then be used to control video game avatars, for example. That process works by assigning tasks to a person's various brain wave patterns, which change depending on the individual's mental state. "There are predefined normal patterns for when you’re awake, drowsy, when you’re asleep, or engaging in activity," says Dr. Madeline Fields, an assistant professor of neurology at Icahn School of Medicine at Mount Sinai. So for instance, an EEG system could prompt a video game character to move forward on a screen if electrodes pick up brain wave patterns associated with drowsiness. The character could then stop moving if a pattern for sleep is detected.

It's important to remember that EEG can't actually read a person's thoughts. Instead, it connects neuronal patterns with actions or mental states. "If I move my right hand, and that creates a very clear signal that links to a computer command, that’s an entirely different beast than me simply wanting my character in the game to turn left and turn right. We don’t read what people are thinking," says Katharine Noe, a neurologist at the Mayo Clinic. The technology may be able to identify patterns that arise from thinking certain words or phrases over and over again, but EEG can't decipher the specific words people are thinking — much less their desires.

EEG can't actually read a person's thoughts

There are some other flaws with the system, too. For starters: the users have hair. In clinical settings, EEG electrodes must be placed very delicately on the scalp in order to work properly. All the oils from the skin must be wiped away first so that the electrodes can be glued to the skin. Without this kind of care, bad measurements can result. And that’s not all: EEG can be confused by outside signals. A lot of objects we use every day have electrical activity, and that can show up on an EEG. "So if you’re holding a cell phone up to your ear, it could cause interference with recording of real cerebral activity," says Noe.

These issues plague the consumer experience of EEG headsets — even those that don’t make lofty claims like the ability to control cars. This year at CES, InteraXon was showcasing its EEG meditation headset; it didn’t fit people’s heads, especially those of people with thick hair. The headset is meant to tell a wearer when he or she is properly meditating — but when I tried it out, the system continuously encountered errors. Before my meditation, it asked me to focus on examples of cities or languages — perhaps as a way to pick up the patterns of when my mind is at work. Then I was asked to clear my mind. But once I was finished meditating, the results seemed to make no sense. I was on a noisy showroom floor filled with journalists loudly performing on-camera presentations next to me, but according to the headset, my mind seemed to pivot between true meditative state and diversion frequently. I couldn’t take its results seriously, given how much was going wrong.

Commercial EEG headsets may have even bigger problems: it’s possible they aren't picking up mental activity at all. Instead, they could be sensing the electric current produced by muscles in the body; heartbeats and eye movements generate voltage that EEGs can read. That makes it hard to tell if a headset is actually measuring brain waves or just a furrowed brow. Emotiv claims its headset can read both muscle movements and brain waves, but it’s difficult to tell which metric is being measured without knowing how the commercial headsets’ algorithms work. And while InteraXon’s headset is supposedly being used in clinical trials to see if it helps cancer patients meditate, there aren’t any studies validating the headset.

EEG holds promise for controlling devices

That’s why Noe wouldn't trust an EEG-controlled car. "I wouldn’t get in the car, and I have to question what signal are they looking at and what is the car actually doing," says Noe. Lara Marcuse, an assistant professor of neurology at the Ican School of Medicine at Mount Sinai agrees. "It’d be hard to control a car," says Marcuse. "You can maybe make a ball move backward and forward, but it'd be hard to give it more direction. It’s at a very early stage."



But Marcuse thinks EEG holds promise for controlling devices. That’s because the electrodes are very good at picking up signals that indicate the body is moving. "Lifting an arm is particularly sensitive on the EEG," says Marcuse. When both arms are at rest, the brain’s neurons produce a specific pattern. But as soon as a person moves an arm or even thinks about moving an arm, the pattern changes distinctly. This could be useful in the field of bionics. Since EEG is so sensitive to arm movements, patients could control a high-tech prosthetic limb, just by concentrating on how they want the limb to move.

Additionally, EEG can record another strong brain pattern known as the P-300 wave. This pattern forms when a person reacts to seeing something he or she is meant to recognize. It's whenever you have an "aha" moment, Marcuse says. "You could use this to dial a phone number," she noted. "If you're on your iPhone and scrolling through pictures of your contacts, you see the person you need to call and then the EEG can call that person."

A likelier future than EEG-controlled cars are headbands that may aid people with disabilities

A likelier future than EEG-controlled cars are headbands that may aid people with disabilities. But for now, those technologies are still too young. So if you see someone promising you can control a car using only your mind, hold onto your wallet — even the most appropriate EEG devices are still in the research stage. Real EEG technology is "more in development, and people are getting close, but it's not like going to a convention and buying a product that’s ready to use," says Noe.