Nature revives human brains

“The mind is a limited machine,”says Marc Berman, a psychologist at the University of Michigan and lead author of a new study that measured the cognitive deficits caused by a short urban walk. “And we’re beginning to understand the different ways that a city can exceed those limitations.”

One of the main forces at work is a stark lack of nature, which is surprisingly beneficial for the brain. Studies have demonstrated, for instance, that hospital patients recover more quickly when they can see trees from their windows, and that women living in public housing are better able to focus when their apartment overlooks a grassy courtyard. Even these fleeting glimpses of nature improve brain performance, it seems, because they provide a mental break from the urban roil.

This research arrives just as humans cross an important milestone: For the first time in history, the majority of people reside in cities.

This research is also leading some scientists to dabble in urban design, as they look for ways to make the metropolis less damaging to the brain. The good news is that even slight alterations, such as planting more trees in the inner city or creating urban parks with a greater variety of plants, can significantly reduce the negative side effects of city life. The mind needs nature, and even a little bit can be a big help.

The reason such seemingly trivial mental tasks leave us depleted is that they exploit one of the crucial weak spots of the brain. A city is so overstuffed with stimuli that we need to constantly redirect our attention so that we aren’t distracted by irrelevant things, like a flashing neon sign or the mobile phone conversation of a nearby passenger on the bus. This sort of controlled perception — we are telling the mind what to pay attention to — takes energy and effort. The mind is like a powerful supercomputer, but the act of paying attention consumes much of its processing power.

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.

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