clipped from www.boston.com

And yet, city life isn't easy. The same London cafes that stimulated Ben Franklin also helped spread cholera; Picasso eventually bought an estate in quiet Provence. While the modern city might be a haven for playwrights, poets, and physicists, it's also a deeply unnatural and overwhelming place.

Natural settings, in contrast, don't require the same amount of cognitive effort. This idea is known as attention restoration theory, or ART, and it was first developed by Stephen Kaplan, a psychologist at the University of Michigan. While it's long been known that human attention is a scarce resource -- focusing in the morning makes it harder to focus in the afternoon -- Kaplan hypothesized that immersion in nature might have a restorative effect.