From Jonah Lehrer:
Humans are a daydreaming species. According to a recent study led by the Harvard psychologists Daniel Gilbert and Matthew A. Killingsworth, people let their minds wander forty-seven per cent of the time they are awake. (The scientists demonstrated this by developing an iPhone app that contacted twenty-two hundred and fifty volunteers at random intervals during the day.) In fact, the only activity during which we report that our minds are not constantly wandering is “love making.” We’re able to focus for that.At first glance, such data seems like a confirmation of our inherent laziness. In a culture obsessed with efficiency, mind-wandering is often derided as useless—the kind of thinking we rely on when we don’t really want to think. Freud, for instance, described daydreams as “infantile” and a means of escaping from the necessary chores of the world into fantasies of “wish-fulfillment.”
In recent years, however, psychologists and neuroscientists have redeemed this mental state, revealing the ways in which mind-wandering is an essential cognitive tool. It turns out that whenever we are slightly bored—when reality isn’t quite enough for us—we begin exploring our own associations, contemplating counterfactuals and fictive scenarios that only exist within the head.