There's a cool piece on the Psychology Today blog that answers the eternal question: Why we are afraid of zombies?

MD Stephen Schlozman says that it centers around pattern recognition and how humans use this process.

A two-year-old can tell you a dog is a dog because it looks like a dog, even if she is being shown a toy poodle and a mastiff. These are adaptive responses that help us to quickly size up a given situation and to draw conclusions around how best to proceed. Mind you, this tendency is also the source of prejudice. Someone might expect that a man in a dark alley intends to take your wallet, and yet he might think the same of you. We make up our minds quickly in part because the drive to categorize and classify declares itself early and profoundly so we can get by in the world largely on autopilot.

The problem with zombies (and ostensibly, other things that we fear) is that zombies break the pattern. It's the familiar becoming increasingly unfamiliar.

That guy is staggering, so perhaps he is drunk. But wait! That kid is also staggering, and kids don't get drunk. And that woman is staggering; when was the last time I saw three staggerers at the same time? Things are not fitting into my usual patterns. I do not recognize this pattern, and I am therefore forced to switch off automatic and to perilously fly manually. Most of the time we're flying by instrument, but not now. Now, we need to look around.

Unfortunately, this doesn't explain the unrelenting horror that is Kim Kardashian.