How Do You Make a Guy Say Yes or No?

A man who is partially paralyzed has been able to communicate with his family in a way that would be impossible for him otherwise. He can hear them through the use of sounds, which he modulates by thinking about something and then pushing it up or down. Scientists hope this could one day lead to people being able to express themselves more easily - even if they are very slow at doing so. But there are still many sceptical scientists out there over its potential benefits.