This is Scientific American 60 Second Science.

I'm Christopher Intagiyata.

Just as we humans understand the shape of our surroundings

by how light reflects off objects, bats use reflections of sounds they produce instead, what's called

echo location. But despite their excellent sensing abilities, one type of obstacle vexes the

animals, smooth vertical surfaces, like windows.

Because windows reflect almost all the bats calls away from the bats at an angle,

creating the illusion of empty space.

To better understand it, you can actually use a visual analogy.

Stephen Greif, a sensory ecologist at the Max Plank Institute for Ornithology.

Imagine standing in a dark room, he says, beside a mirror.

And that if you take a flashlight into your hand and shine it from the side onto this mirror,

you would see that all the light is being reflected away.

You would see it on the other side of the wall. So even

visually this would look to you like it's there's a hole in the wall. There's nothing

coming back from this place. Light wouldn't come back to you unless you aim to

the flashlight more or less perpendicular to the mirror.

And same for bats and their calls.

This perceptual glitch meant that in lab tests,

90% of the bats banged into a smooth vertical surface.

And by the way, the researchers say that none were hurt.

But here's the interesting bit.

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