The interface consists, essentially, of a keyboard displayed on a computer screen.The way this works is that all the letters come up, and each one of them flashes individually,says Williams. And what your brain does is, if you are looking at the ¡'s on the screen and all the other letters are flashing, nothing happens. But when the ¡ flashes, your brain says, Hey, wait a minute. Something's different about what I was just paying attention to.And you see a momentary change in brain activity.