A theory called the "uncanny valley" says we tend to feel attracted to inanimate objects with human traits, the way a teddy bear or a rag doll seems cute.
Our affection grows as an object looks more human. But if it looks too human, we suddenly become repulsed.
Instead of seeing what's similar, we notice the flaws — and the motionless eyes or awkward movements suddenly make us uncomfortable.
This explains The Polar Express and, more recently, the failure of Mars Needs Moms.
Judge for yourself:
Yeah, that's kind of creepy.