Going, Going ... Up a Hill

The great Yankee slugger Mickey Mantle, when asked about his uncanny ability to blast home runs, famously replied: “I never really could explain it. I just saw the ball as big as a grapefruit.” It’s not surprising really that the Hall-of-Famer couldn’t explain his experience in the batter’s box. What he was describing was one of the fundamental mysteries of human perception, one that has intrigued psychologists for more than half a century.

Psychologist Dennis Proffitt took The Mick’s comment and ran with it. A perception expert at the University of Virginia, Proffitt wondered if other, lesser athletes had similar experiences. So he went to a local softball game, and at the end of the game he asked the players to estimate the size of the ball. The bigger they perceived the ball to be, the higher their batting average, and vice versa.

What this small study suggests, according to Proffitt, is that human perception is much more complex than simple vision. It includes vision—what’s actually recorded on the retina—but the brain mixes that imagery with all sorts of mental and emotional baggage. For poor hitters, the ball is perceived as tiny and distant because it is “out of reach”—beyond their ability to connect with it, emotionally and actually.

Ultimately, Proffitt believes, such perceptual “errors” may be beneficial. Indeed, a distorted view of our surroundings may be crucial to the way we navigate through a dangerous world. Proffitt and his colleagues have run a whole battery of experiments to demonstrate this idea, none having to do with baseball, all reported in the journal Perspectives on Psychological Science. In one series of experiments, they had students stand at the bottom of various hills and estimate the angle of the slope. They were very bad at this. For example, state law in Virginia prohibits any roads with a grade greater than 9 degrees; the students consistently estimated steep roads to be 25 degrees or more.

This universal tendency to distort steepness can probably be traced back to our ancient ancestors, who constantly had to conserve energy. They did this in part by choosing to (or choosing not to) climb a particular hill. This wasn’t a conscious calculation, of course; they didn’t estimate each hill’s slope in degrees and weigh it against their stamina. But that’s in effect what they were doing day in and day out on an unconscious level. And what we still do today. Proffitt showed this in several experiments: He deliberately fatigued some participants (by having them jog); he made others wear a heavy backpack; he compared fit and unfit students; and he observed the elderly and frail. In every case, the participants' fatigue (real or anticipated) made them overestimate the slope of the hill in front of them.

And it’s not just energy. Proffitt also had participants stand on the top of a 30 degree hill. That’s a very steep hill, almost impossible to descend without falling. He found that people consistently saw the hill as steeper when they were at the top of it than when they were at the bottom. Why? Probably an ingrained fear of falling, Proffitt speculates. The top of a 30 degree hill is a dangerous place, he notes. People likely see steep hills as even steeper because part of the mind is imagining a skull-cracking injury—or death.

Happily, all of these calculations take place instantaneously outside our awareness. Imagine trying to get through a day if you had to considers risks and benefits of every footstep. As Proffitt says, “A principal function of perception is to defend people from having to think.” Or as another famous Yankee, Yogi Berra, once quipped: “You can’t think and hit at the same time.”

For more insights into human nature, visit the Association for Psychological Science website at www.psychologicalscience.org.