kgp

http://money.cnn.com/galleries/2009/technology/0911/gallery....

"I think humans constantly scan their environment to build a mental model of what's around them. And the harder a scene is to parse, the less energy you have left for conscious thoughts. A cluttered room is literally exhausting."

On a related note , Steve Jobs has no furniture.

The research mentioned in the above article was actually done by Greg Korah Hartman. He did this for a google tech talk , you can view it over here http://www.youtube.com/watch?v=L2SED6sewRw .