In fact, researchers at Stanford University have found that the more we multitask, the worse we are at it. When tested on memory, ability to switch tasks and ability to focus exclusively on one task, heavy multitaskers (that is, people who reported that they routinely used multiple media at once) scored worse across the board. While non-multitaskers were able to switch their focus completely between tasks, the experienced multitaskers were not able to stop thinking about the other activities while focusing on the job at hand.
In one test, researchers told the subjects to focus on some red rectangles on a computer screen and note changes in position. They then filled the rest of the screen with some useless shapes. A normal person had no problem with the task, but the mutlitaskers couldn't keep from getting distracted by the irrelevant noise. That's right. Multitasking happens to be the one skill that practice makes you worse at. Well, that and the people who consider themselves "heavy multitaskers" also tend to be the type who lose an entire workday every time someone brings a laser pointer into the office. Either way, our projections indicate that if work habits continue on their current path, in 30 years there won't be a single productive employee remaining on earth.
Google corporate HQ, 2047.