http://www.nytimes.com/2010/06/29/science/29tier.html?pagewanted=1&_r=3&

  

A wandering mind can protect you from immediate perils and keep you on course toward long-term goals. Sometimes daydreaming is counterproductive, but sometimes it fosters creativity and helps you solve problems.

Mind wandering, as psychologists define it, is a subcategory of daydreaming, which is the broad term for all stray thoughts and fantasies, including those moments you deliberately set aside to imagine yourself winning the lottery or accepting the Nobel. But when you’re trying to accomplish one thing and lapse into “task-unrelated thoughts,” that’s mind wandering.

But mind wandering clearly seems to be a dubious strategy, if, for example, you’re tailgating a driver who suddenly brakes. Or, to cite activities that have actually been studied in the laboratory, when you’re sitting by yourself reading “War and Peace” or “Sense and Sensibility.”

If your mind is elsewhere while your eyes are scanning Tolstoy’s or Austen’s words, you’re wasting your own time. You’d be better off putting down the book and doing something more enjoyable or productive than “mindless reading,” as researchers call it.

But during some episodes of mind wandering, both networks are firing simultaneously, according to a study led by Kalina Christoff of the University of British Columbia. Why both networks are active is up for debate. One school theorizes that the executive network is working to control the stray thoughts and put the mind back on task.

Another school of psychologists, which includes the Santa Barbara researchers, theorizes that both networks are working on agendas beyond the immediate task. That theory could help explain why studies have found that people prone to mind wandering also score higher on tests of creativity, like the word-association puzzle mentioned earlier. Perhaps, by putting both of the brain networks to work simultaneously, these people are more likely to realize that the word that relates to eye, gown and basket is ball, as in eyeball, ball gown and basketball.

To encourage this creative process, Dr. Schooler says, it may help if you go jogging, take a walk, do some knitting or just sit around doodling, because relatively undemanding tasks seem to free your mind to wander productively. But you also want to be able to catch yourself at the Eureka moment.

“For creativity you need your mind to wander,” Dr. Schooler says, “but you also need to be able to notice that you’re mind wandering and catch the idea when you have it. If Archimedes had come up with a solution in the bathtub but didn’t notice he’d had the idea, what good would it have done him?”