The Autumn of the Multitaskers

"Multitasking messes with the brain in several ways. At the most basic level, the mental balancing acts that it requires—the constant switching and pivoting—energize regions of the brain that specialize in visual processing and physical coordination and simultaneously appear to shortchange some of the higher areas related to memory and learning. We concentrate on the act of concentration at the expense of whatever it is that we’re supposed to be concentrating on."

http://www.theatlantic.com/doc/200711/multitasking