Researchers in California have created a way to place a call on a cell phone using just your thoughts. Their new brain–computer interface is almost 85 percent accurate for most people after only a brief training period. The system was developed by Tzyy–Ping Jung.

Like many other such interfaces, Jung's system relies on electroencephalogram (EEG) electrodes on the scalp to analyze electrical activity in the brain. An EEG headband is hooked up to a Bluetooth module that wirelessly sends the signals to a Nokia N73 cell phone, which uses algorithms to process the signals.

Participants were trained on the system via a novel visual feedback system. They were shown images on a computer screen that flashed on and off almost imperceptibly at different speeds. These oscillations can be detected in a part of the brain called the midline occipital. Jung and his colleagues exploited this by displaying a keypad on a large screen with each number flashing at a slightly different frequency. For instance, “1” flashed at nine hertz, and “2” at 9.25 hertz, and so on. Jung says this frequency can be detected through the EEG, thus making it possible to tell which number the subject is looking at.

“From our experience, anyone can do it. Some people have a higher accuracy than others,” says Jung, who himself can only reach around 85 percent accuracy. 10 subjects were asked to input a 10–digit phone number, and seven of them achieved 100 percent accuracy.

In theory, the approach could be used to help severely disabled people communicate, says Jung. But he believes the technology doesn't have to be limited to such applications. “I want to target larger populations,” he says.