Anyone who's ever meditated will tell you there's a lot of interference going on in the average mind. Focussed attention is a rare thing. Which is one reason it was always going to be difficult to build a computer that could read your mind: for every thought worth reading, there are hundreds of trivial, irrelevant ones worth ignoring.
It's as if the brain needs recreation time, where it can generate as much mindlessness as it likes. Focussed attention is a rare thing partly because it takes a lot of work.
This is a problem that a research team from Switzerland's Ecole Polytechnique Federale de Lausanne have been grappling with. The team, led by Professor José del R. Millán from the school's Center for Neuroprosthetics, are working on a computer that reads mental intention. In other words, one that sorts through all the mental flotsam and determines what you really want it to do.
The advantage of this brain-computer interface is not only that it makes it a lot easier to drive, say, a wheelchair with your mind, but it also allows for multitasking. Which means that you don't have to spend every ounce of mental power on directing the computer - you can actually spend time using your mind to, er, think.
Here is Professor Millán explaining how it works: