"Mori's hypothesis states that as a robot is made more humanlike in its appearance and motion, the emotional response from a human being to the robot will become increasingly positive and empathic, until a point is reached beyond which the response quickly becomes that of strong repulsion. However, as the appearance and motion continue to become less distinguishable from a human being, the emotional response becomes positive once more and approaches human-to-human empathy levels.
This area of repulsive response aroused by a robot with appearance and motion between a "barely-human" and "fully human" entity is called the uncanny valley. The name captures the idea that a robot which is "almost human" will seem overly "strange" to a human being and thus will fail to evoke the empathetic response required for productive human-robot interaction."
Apparently, this isn't really embraced as legitimate scientific theory, and I can appreciate that, but man, it sure feels true. If you look at this graph, you see what the dip in the valley equates to - a corpse and a zombie. Wow, that really says it all. It sort of explains our obsession (or mine at least) with zombie movies.
Zombies are the versions of us without the free will - I don't think there's anything more terrifying than seeing something human-like on auto-pilot (while trying to devour my flesh). This is probably what freaks me out about religious zealots, it really seems like no one's behind the wheel, making the decisions (while trying to devour my flesh).
Maybe they're not all bad...