SSS 2011-02-16（在线收听）

This is Scientific American's 60-Second Science. I'm Karen Hopkin. This will just take a minute.

Stand at the bottom of a big hill and you can exhaust yourself just thinking about climbing it. But a new study suggests it's not as bad as it looks. Because people tend to overestimate the steepness of slopes, and not because we're lazy.

Psychologists have long assumed that our misperception of slope was biased by fatigue or even fear of falling. If we see going up or down a hill as difficult, our perception could be influenced by our point of view.

But researchers at Ohio State University have found it isn't so. The scientists asked 200 passersby to estimate the angle of a set of stairs, and another 200 to do the same for an escalator—which, of course, requires no effort to ascend. In each case, half the subjects looked from the bottom and half from the top.

The results: viewers consistently overestimated the slant of each slope by about 20 degrees. The work appears in the journal Psychological Science.

The researchers are not sure what drives this angular disparity. Perhaps it's because our visual system evolved to be overly sensitive to even slight departures from the horizontal, to help keep us upright. Because 'not falling down' is the first step to making it up that hill.

Thanks for the minute. For Scientific American's 60-Second Science, I'm Karen Hopkin.