Nature at a Glance

Imagine that you arrive by bus at a vacation spot you’ve never been to before. You get out and look around. What do you notice at first glance? Well, you can’t miss the large lake right in front of you; should be some good water skiing there. There’s a snow-capped mountain rising in the distance, and a copse of hemlock trees just to the left. The lodging must be in that chalet down to the right. The screened porch looks inviting, and the weather’s perfect.

Now imagine you’re a criminal on the lam, and you step off the same bus. What do you see? Well mostly you see a vast open space. Other than that small stand of trees, there is very little place to hide. You feel exposed, vulnerable. The water is simply an obstacle between you and freedom in that mountain beyond. Is there a path? You notice a man-made structure, always a threat. At least it’s not cold.

Same landscape, yet two very different perceptions. And this is not a matter of interpretation or judgment; a glance is way too rapid for that. It’s what the vacationer and the criminal actually see. That’s because even something as basic as vision is intimately rooted in our fears and in our ancient strategies for survival. Our brains evolved when there were threats everywhere, so we are highly tuned to extract the most meaningful information with even the first fleeting glance. A long lingering glance might prove fatal. The escaped convict (like our ancient ancestors) doesn’t have the luxury of noticing details like hemlocks and verandas or even lakes and mountains. The need and desire for safety trumps all other detail in the mind’s eye.

We all have a bit of the escaped convict’s vigilance deep-wired into our neurons. At least that’s the theory, which a pair of MIT scientists decided to test in the lab. Psychologists Michelle Greene and Aude Oliva wanted to explore how we see the natural world in the split second of a first encounter. What information is so essential and so privileged that it’s processed instantaneously? And what’s mere gilding that can be added later, as we continue to scope out the new territory?

The psychologists had volunteers look at hundreds of color photographs of various natural scenes, and very rapidly categorize them. Sometimes they were asked to categorize the landscapes according to common physical features like oceans and forests and fields and rivers. Other times they classified the landscapes according to fundamental survival features—ease of navigation, openness, naturalness and temperature. The researchers timed how long it took the volunteers to categorize each vista, down to the millisecond.

It’s remarkable how fast the mind “sees” what it needs to see. As reported in the March issue of the journal Psychological Science, the survival features were processed almost instantaneously—as quickly as 19 milliseconds, much faster than a finger snap. The common geographical features were also processed quickly—but almost as an afterthought compared to the automatic perception of things like open space and escape routes. This makes sense, since categories like mountain and lake came much later to humans, as the slow and analytic mind evolved.

The brain was at its fastest when categorizing landscapes simply as natural, as opposed to manmade. Eons of evolution appear to have linked the brain intimately to the natural world—but not yet to the civilized world, which still requires some (relatively) slower analysis to comprehend. This raises the intriguing possibility that we can know a landscape is natural even before we “see” the mountains and meadows and waterfalls that give it its nature.

For more insights into the quirks of human nature, visit “We’re Only Human” at www.psychologicalscience.org/onlyhuman. Excerpts from the blog also appear regularly in the magazine Scientific American Mind and at http://www.sciam.com/.