The Science Of Scary: 10 Reasons Why You Love Being Scared

4. The Uncanny Valley

There are lots of different types of fear - gross-out, horror, terror - but the one that's most difficult to get a handle on is "creepy".

"Creepy" is a quality of unease that we just can't quite put our fingers on. When something gives you the creeps, as opposed to being out-and-out scary it's a feeling that something is "wrong" as opposed to "dangerous" and will often fall into the uncanny valley.

The uncanny valley is a theory in aesthetics, and often robotics, that describes the feelings of revulsion and creepiness elicited by objects that look almost, but not quite, like natural beings.

The "valley" is the swift drop in acceptability of an object's appearance as it approaches "lifelike". A teddy is cute, because it doesn't really look like anything other than a teddy. Give that teddy a set of human teeth and all of a sudden it's something that slithered out of your nightmares. This is the same thing that makes lifelike robots so fricking creepy.

The uncanny valley response may be rooted in our ingrained fears of death, disease and disfigurement (or perhaps of the robot uprising). We don't like the pallid, impassive faces of androids because they look so much like the face of a corpse.

It may also be because these objects violate some or all of the usual cues we use to interact with other humans. Because they're so lifelike, our brains treat them, not as objects that look a bit like humans, but as humans that are not behaving in a way that we would expect, the cognitive dissonance of this situation gives us the creeps.

In short, the reason why a little girl in a nightdress scuttling around like a crab is so scary, is because she just scuttled into the uncanny valley.