For years, the conventional wisdom on multitasking has been that it's a valuable skill necessary when competing in today's mile-a-minute world of 24-hour news, e-commerce and portable everything. It's difficult to find a help wanted ad that doesn't list "multitasking" among the skills an employer demands of its ideal candidate. And to some degree, certainly, multitasking is essential -- back in the stone age when we had to hunt for food while fending off sabre-toothed tiger attacks, it came in awfully handy. But you can take anything too far. If I were posting a help wanted ad today -- depending on the job -- I would include "the ability to focus deeply on one task for extended periods of time" as an essential requirement; which today is becoming a rarer skill than "multitasking."

For some people, multitasking isn't just a skill -- it's a kind of addiction. My wife, for instance, finds it nearly impossible to read a book without the television on. I'll often find her with a magazine in one hand, typing on a laptop -- writing something and instant messaging simultaneously -- while the TV blares. According to numerous new studies (I keep telling her), this may feel like an efficient way to be, but it's not -- in fact, "extreme" multitasking can mimic the same brain patterns as ADD. A Vanderbilt study described the effects of problem multitasking in the brain as a kind of anti-productive "response selection bottleneck," which leads to lost time as the brain decides which task to perform. Another noted that extreme multitasking "contributes to the release of stress hormones and adrenaline" which can lead to long-term health problems and short-term memory problems. Yet another found that multitasking adversely effects the way we learn: "if you learn while multitasking, that learning is less flexible and more specialized, so you cannot retrieve the information as easily," according to UCLA psychology professor Russell Poldrack.

What we don't know is how this will effect the current generation of teenagers, who are far and away the most inveterate media multitaskers the world has known. "They develop a more superficial style of study and may not learn material as well," said cognitive scientist David Meyer. "What they get out of their study might be less deep. The belief [among teens] is that they're getting good at this and that they're much better than the older generation at it and that there's no cost to their efficiency." We'll see about that!

I'm the first to admit, I'm not immune to the multitasking bug. Right now I'm fighting a very serious urge to check my email and look at the top stories on Digg. But there's some sort of latent Puritanical voice in my head that counsels me to do the work until it's done. Sometimes the voice wins out, sometimes it doesn't. [Update: I have no new messages in my inbox.]

"There is time enough for everything in the course of the day, if you do but one thing at once, but there is not time enough in the year, if you will do two things at a time."

"This steady and undissipated attention to one object, is a sure mark of a superior genius; as hurry, bustle, and agitation, are the never-failing symptoms of a weak and frivolous mind."

- Lord Chesterfield

"To do two things at once is to do neither."
- Publilius Syrus, Roman slave, first century B.C.

"I think your suggestion is, Can we do two things at once? Well, we're of the view that we can walk and chew gum at the same time."
- Richard Armitage, deputy secretary of state, on the wars in Afghanistan and Iraq, June 2, 2004 (Armitage announced his resignation on November 16, 2004.)

Links: The Atlantic, The New Atlantis,