This is Your Brain on Nature

August 22, 2018

 

 

WHEN YOU HEAD OUT to the desert, David Strayer is the kind of man you want behind the wheel. He never texts or talks on the phone while driving. He doesn’t even approve of eating in the car. A cognitive psychologist at the University of Utah who specializes in attention, Strayer knows our brains are prone to mistakes, especially when we’re multitasking and dodging distractions. Among other things, his research has shown that using a cell phone impairs most drivers as much as drinking alcohol does.

 

Strayer is in a unique position to understand what modern life does to us. An avid backpacker, he thinks he knows the antidote: Nature.

 

On the third day of a camping trip in the wild canyons near Bluff, Utah, Strayer is mixing up an enormous iron kettle of chicken enchilada pie while explaining what he calls the “three-day effect” to 22 psychology students. Our brains, he says, aren’t tireless three-pound machines; they’re easily fatigued. When we slow down, stop the busywork, and take in beautiful natural surroundings, not only do we feel restored, but our mental performance improves too.

 

Strayer has demonstrated as much with a group of Outward Bound participants, who performed 50 percent better on creative problem-solving tasks after three days of wilderness backpacking. The three-day effect, he says, is a kind of cleaning of the mental windshield that occurs when we’ve been immersed in nature long enough. On this trip he’s hoping to catch it in action, by hooking his students—and me—to a portable EEG, a device that records brain waves.

 

Science is proving what we've always known intuitively: Nature does good things to the human brain. It makes us healthier, happier, and smarter.

 

“On the third day my senses recalibrate—I smell things and hear things I didn’t before,” Strayer says. The early evening sun has saturated the red canyon walls; the group is mellow and hungry in that satisfying, campout way. Strayer, in a rumpled T-shirt and with a slight sunburn, is definitely looking relaxed. “I’m more in tune with nature,” he goes on. “If you can have the experience of being in the moment for two or three days, it seems to produce a difference in qualitative thinking.”

 

Strayer’s hypothesis is that being in nature allows the prefrontal cortex, the brain’s command center, to dial down and rest, like an overused muscle. If he’s right, the EEG will show less energy coming from “midline frontal theta waves”—a measure of conceptual thinking and sustained attention. He’ll compare our brain waves with those of similar volunteers who are sitting in a lab or hanging out at a parking lot in downtown Salt Lake City.

 

While the enchiladas are cooking, Strayer’s graduate students tuck my head into a sort of bathing cap with 12 electrodes embedded in it. They suction-cup another 6 electrodes to my face. Wires sprouting from them will send my brain’s electrical signals to a recorder for later analysis. Feeling like a beached sea urchin, I walk carefully to a grassy bank along the San Juan River for ten minutes of restful contemplation. I’m supposed to think of nothing in particular, just watch the wide, sparkling river flow gently by. I haven’t looked at a computer or cell phone in days. It’s easy to forget for a few moments that I ever had them.

 

Motivated by large-scale public health problems such as obesity, depression, and pervasive nearsightedness, all clearly associated with time spent indoors, Strayer and other scientists are looking with renewed interest at how nature affects our brains and bodies. Building on advances in neuroscience and psychology, they’ve begun to quantify what once seemed divine and mysterious. These measurements—of everything from stress hormones to heart rate to brain waves to protein markers—indicate that when we spend time in green space, “there is something profound going on,” as Strayer puts it.

 

Japanese researchers, led by Yoshifumi Miyazaki at Chiba University, sent 84 subjects to stroll in seven different forests, while the same number of volunteers walked around city centers. The forest walkers hit a relaxation jackpot: Overall they showed a 16 percent decrease in the stress hormone cortisol, a 2 percent drop in blood pressure, and a 4 percent drop in heart rate. Miyazaki believes our bodies relax in pleasant, natural surroundings because they evolved there. Our senses are adapted to interpret in- formation about plants and streams, he says, not traffic and high-rises.

 

All this evidence for the benefits of nature is pouring in at a time when disconnection from it is pervasive, says Lisa Nisbet, a psychology professor at Canada’s Trent University. We love our state and national parks, but per capita visits have been declining since the dawn of email. So have visits to the backyard. One recent Nature Conservancy poll found that only about 10 percent of American teens spend time outside every day. According to research by the Harvard School of Public Health, American adults spend less time outdoors than they do inside vehicles—less than 5 percent of their day.

 

My own city brain, which spends much of the year in Washington, D.C., seems to like the Utah wilderness very much. By day, on David Strayer’s camping trip, we hike among flowering prickly pear cacti; by night we sit around the campfire. Strayer’s students seem more relaxed and sociable than they do in the classroom, he says, and they give much better presentations.

 

What’s going on inside their brains and mine?

 

 

A lot of different things, judging from the neuroscience research that’s starting to come in. Korean researchers used functional MRI to watch brain activity in people viewing different images. When the volunteers were looking at urban scenes, their brains showed more blood flow in the amygdala, which processes fear and anxiety. In contrast, the natural scenes lit up the anterior cingulate and the insula—areas associated with empathy and altruism.

 

Maybe nature makes us nicer as well as calmer.

 

It may also make us nicer to ourselves. Stanford researcher Greg Bratman and his colleagues scanned the brains of 38 volunteers before and after they walked for 90 minutes, either in a large park or on a busy street in downtown Palo Alto. The nature walkers, but not the city walkers, showed decreased activity in the subgenual prefrontal cortex—a part of the brain tied to depressive rumination—and from their own reports, the nature walkers beat themselves up less. Bratman believes that being outside in a pleasant environment takes us outside of ourselves in a good way. Nature, he says, may influence “how you allocate your attention and whether or not you focus on negative emotions.”

 

Strayer is most interested in how nature affects higher order problem solving. His research builds on the attention restoration theory proposed by environmental psychologists Stephen and Rachel Kaplan at the University of Michigan. They argue that it’s the visual elements in natural environments—sunsets, streams, butterflies—that reduce stress and mental fatigue. Fascinating but not too demanding, such stimuli promote a gentle, soft focus that allows our brains to wander, rest, and recover from what one researcher called the “nervous irritation” of city life. “Soft fascination ... permits a more reflective mode,” wrote the Kaplans—and the benefit seems to carry over when we head back indoors.

 

“At the end of the day, we come out in nature not because the science says it does something to us, but because of how it makes us feel.”

 

A few months after our Utah trip, Strayer’s team sent me the results of my EEG test. The colorful graph charted the power of my brain waves at a range of frequencies and compared them with samples from the two groups that had stayed in the city. My theta signals were indeed lower than theirs; the soft fascination of the San Juan River had apparently quieted my prefrontal cortex, at least for a while.

 

So far, says Strayer, the results are consistent with his hypothesis. But even if the study bears it out, it won’t offer anything like a full explanation of the brain-on-nature experience. Something mysterious will always remain, Strayer says, and maybe that’s as it should be. “At the end of the day,” he says, “we come out in nature not because the science says it does something to us, but because of how it makes us feel.”

 

Abridged from an article by Florence Williams, originally published:

https://www.nationalgeographic.com/magazine/2016/01/call-to-wild/


 

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