The uncanny valley makes sense to most of us, but is still largely unexplained, at least by science.
From the cognitive science perspective:
"If you look humanlike but your motion is jerky or you can't make proper eye contact, those are the things that make them uncanny," Saygin told InnovationNewsDaily. "I think the key is that when you make appearances humanlike, you raise expectations for the brain. When those expectations are not met, then you have the problem in the brain."
Mori's metaphor might not work beyond the heuristic level, at least for these scientists:
All Too Human Saygin and fellow researchers don't think the phenomenon follows the valley metaphor exactly. Instead, they suggest the uncanny valley sensation arises when an artificial figure looks or behaves real enough to trigger a mental switchover - the viewer's brain suddenly begins to consider the figure as a possible human. The artificial figure almost inevitably fails such close inspection.
(thanks to Ed Webb and all other friends of Infocult)