John Tierney in The New York Times:
In the past, daydreaming was often considered a failure of mental discipline, or worse. Freud labeled it infantile and neurotic. Psychology textbooks warned it could lead to psychosis. Neuroscientists complained that the rogue bursts of activity on brain scans kept interfering with their studies of more important mental functions.
But now that researchers have been analyzing those stray thoughts, they’ve found daydreaming to be remarkably common — and often quite useful. 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. Consider, for instance, these three words: eye, gown, basket. Can you think of another word that relates to all three? If not, don’t worry for now. By the time we get back to discussing the scientific significance of this puzzle, the answer might occur to you through the “incubation effect” as your mind wanders from the text of this article — and, yes, your mind is probably going to wander, no matter how brilliant the rest of this column is.
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.
More here.