A nature trail leads away from the campgrounds in the center of Reston, Virginia's Lake Fairfax Park. (Fritz Hahn/The Washington Post)

Human beings love being outside — an estimated 8 billion visits are made annually to natural protected areas, a number that's larger than the total world population.

But could spending time in natural scenery also have larger implications for how we behave politically, or how we treat one another?

A new study suggests the answer is yes.

The paper, just out in the Journal of Environmental Psychology, is by psychologist John M. Zelenski and several other colleagues from Carleton University in Ottawa, Canada. In the study, the researchers wanted to test the idea that there's a link between actually experiencing the natural world, and behaving in a sustainable way. "We hypothesize that participants exposed to nature will make more cooperative, and thus sustainable, choices," they wrote.

How do you study this idea? The research design was a series of experiments with college undergraduates, who, in the first of three studies, were asked to watch a 12 minute video. In some cases, it was a nature video — BBC's "Planet Earth," no less. In others, it was a documentary about New York City's impressive — but also quintessentially urban — architecture.

Then the subjects played a game that the researchers called a "fish-themed commons dilemma." In the game, a group of people decide how many fish to catch over the course of a number of "seasons." Players receive 10 cents per fish caught (but it costs 5 cents to travel out to sea to catch them); the ocean initially contains 50 fish; and over seasons, fish regenerate at a fixed rate.

The participants were playing against other simulated fishermen who had been programmed to "behave relatively cooperatively," rather than greedily (i.e., catching too many fish to maximize their profits, but ultimately crashing the fishery).

The results showed, sure enough, that those who had watched the nature video "harvested significantly fewer fish per season." And moreover, the virtual oceans in which they fished supported sustainable fishing for longer. In contrast, those who watched the architecture video harvested more fish early on, going for the money.

"By season 15, 49.09% of the architecture condition's oceans went extinct, compared to 28.57% in the Planet Earth condition," wrote the authors.

In several subsequent studies, meanwhile, the researchers modified the experimental conditions in order to test the strength of the results, a common practice in psychology studies. Thus, in another study, three different nature videos now showed a forest, a pack of wolves hunting, and a destructive flood. The architecture videos, meanwhile, showed an exciting Las Vegas scene and an old rundown house. Thus, people saw both pleasant and unpleasant images of nature and a built environment.

Even so, the nature focused videos once again had the effect of "producing more pro-social responses" in the fishing game. "These effects do not depend on nature's pleasantness," noted the authors.

So why does viewing nature — as opposed to something constructed by humans — seem to have this effect? The authors say they don't know the exact mechanism, though they speculate that it has something to do with "shifting people's preferences from immediate gratification to larger but more distant payoffs."

The study also evokes E.O. Wilson's well-known biophilia hypothesis, which suggests that we have an evolutionary yearning to be in natural environments and among other creatures due simply to where we ultimately come from, back in deep time. The idea here, wrote the authors, is that "we evolved in natural environments and, thus, they still support optimal human functioning."

If nature exposure works to change our behavior and make us more cooperative, there could be considerable implications for environmental campaigns. Thus, the authors suggest that climate change advocates might consider using nature-focused messages, rather than economic or national security framings, to advance their cause. After all, global warming is ultimately an issue of the people of the world dumping too much of their waste into the atmospheric commons, and thus far failing to cooperate adequately on strategies for reduction.

The overall results, the paper concluded, also "suggest that societies might consider investing more in nature."