21st
A 2007 study by Michael Kane of the University of North Carolina found that our minds drift away from our tasks fully one-third of the time. And this suggests that daydreaming can actually be useful — because if it were such a bad thing, it’s unlikely that we’d do it so often.
Why do our minds wander? Brain-scanning technology has uncovered some clues. It turns out that when your mind drifts, your temporal lobes — which are associated with processing long-term memories — become busier. So when you float off into a reverie, you’re actually doing important data-storage work. Daydreaming isn’t just the mind’s way of processing information, though. Other scans have found that the wandering mind also utilizes the prefrontal cortex, the part of our brain that’s involved in problem-solving. (via Clive Thompson on Why Idling Mind Is Mother of Invention | Magazine
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