I remember making an excursion as a child to the Australian Museum with my parents. There must have been an exhibition on everyday life, or city living, or some such thing, for in one darkened room we came across a life-sized tableau of a family in their living room. Here were a wax mother and father, their two waxen offspring, a sofa, bookshelves and a TV. Always fascinated by mannequins, I walked right up to them for a closer look, and, in an early experience of the uncanny valley, got a real shock.
Whoever had sculpted the faces had obviously not done so with close scrutiny (let alone aesthetics) in mind. The entire family looked like Freddy Krueger, apart from Mum, who in her straw-like wig also bore a passing resemblance to Worzel Gummidge. She bared her teeth at me in a sinister grin. For several nights following that visit the Krueger family haunted me, and I still have quite a clear image of Mum in my mind.
Uncanny valley is a theory devised by Japanese roboticist Masahiro Mori to explain a perceived drop in positive reaction when someone is presented with the appearance of realistic, but not quite convincing, humanity.
This is a good example.