"Virtual reality is a safe testing ground," says Bayliss. "We can see what works and what doesn't without the danger of driving a wheelchair into a wall. We can learn how brain interfaces will work in the real world, instead of how they work when someone is just looking at test patterns and letters. The brain normally interacts with a 3-D world, so I want to see if it gives off different signals when dealing with a 3-D world than with a chart."
The brain signal Bayliss listens for is called the "P300 evoked potential." It's not a specific signal that could be translated as "Aunt Nora" or "stop at the red light," but rather a sign of recognition-more like "That's it!"
"It's as if each neuron is a single person who's talking," explains Bayliss. "If there's just one person, then it's easy to hear what he's saying, but the brain has billions of neurons, so imagine a room full of a billion people all talking at once. You can't pick out one person's voice, but if everyone suddenly cheers or oohs or aahs, you can hear it. That's what we listen for, when several neurons suddenly say 'that's it!' "
Bayliss looks for this signal to occur in sync with a light flashing on the television or stereo. If the rhythm matches the blinks of the stereo light, for instance, the computer knows the person is concentrating on the stereo and turns it on. A person doesn't even have to look directly at the
Contact: Jonathan Sherwood
University of Rochester