A paper that was published in the December issue of Psychological Science has attracted some attention recently because of some of its potential implications, namely that living in urban environments can harm our cognitive control. It's an intriguing idea, and there is some experimental support for it, but right now, the theory behind the work appears to have some inconsistencies with other recent results.

The basic idea is derived from the fact that the brain has two forms of attention. The first is a bottom-up process, in which low-level, subconscious parts of the brain identify something worthy of attention and alert the conscious portions. The alternate, top-down version (often termed "executive") kicks in when the conscious part of the brain decides to pay attention to something, and directs sensory resources to do so.

According to the theory, which its proponents term "attention restoration theory," or ART, this latter form of attention is mentally taxing. People can only maintain focus for a finite amount of time before exhausting their mental resources and finding themselves in need of a recharge, the restoration portion of ART. That restoration comes from the mental equivalent of peace and quiet—periods of time when the bottom-up portion of things is not demanding that the conscious part of the brain decide whether something is worth further attention.

Thinking better?

Supposedly, natural environments help enable that restoration process. They contain information that the unconscious portions of the brain are better able to deal with, allowing it to leave the conscious portion undisturbed. Urban environments, in contrast, contain a host of potential distractions, which keeps the brain too busy to recover. The paper focuses on testing this contention via two different experimental setups.

In the first, the authors had their subjects perform a mentally taxing task: listen to a string of digits, and then repeat the string in reverse. After a bit more than a half-hour of this, the subjects were sent on a walk, half through the campus arboretum, the other half through downtown. Their performance on a similar digit reversal task was then measured; those who had walked among the trees outperformed the subjects who went through town, a result that held up when the same subjects were invited back a week later to perform the opposite walk.

In a second test, the walk was replaced by pictures of natural and urban areas, and the test of attention skills was switched to the ANT suite, which includes tests that distinguish between both bottom-up and top-down attention. The tests indicated that, while bottom-up skills were indifferent to the type of picture viewed, those who saw nature scenes had better performance in the tests of executive attention.

Now, it would be easy—and stupid—to view this as indicating that an urban environment damages the brain (which, obviously, means someone has done so). If ten minutes of looking at pictures could have a restorative effect, then it's possible that simply choosing your computer's desktop background could potentially counteract any urban-generated issues. A lot of settings also don't fall neatly into a urban/natural category. The view from the home office here is dominated by water and an island with a mixture of trees and soccer fields—with a suspension bridge and the FDR drive in the background. What exactly am I getting out of that?

The ART proposal also doesn't seem to be thoroughly integrated with a lot of the rest of psychology. For starters, they equate visual and audio attention in their exercises (the digit task is audible, while the subjects looked at pictures). The test then focused, at least in part, on the working memory needed to reverse digits. I say "in part" because working memory seems to hold fewer items than the number of digits used in many tests. Finally, there's data indicating that components of natural scenes actually grab more of a share of conscious attention than the inanimate objects that populate urban scenery, possibly as a result of the fact that we evolved where natural objects were all that mattered.

As someone who gets a lot out of the time I spend in scenic places, there's little doubt in my mind that natural scenery can be beneficial to one's mental state. But there's a big gap between that and the ART model, which proposes some very specific cause-and-effect relationships.

Psychological Science, 2008. DOI: 10.1111/j.1467-9280.2008.02225.x

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