This is what we found on Wikipedia regarding the Uncanny Valley:

The uncanny valley (Japanese: 不気味の谷, Hepburn: bukimi no tani) effect is a hypothesized psychological and aesthetic relation between an object's degree of resemblance to a human being and the emotional response to the object. Examples of the phenomenon exist among robotics, 3D computer animations and lifelike dolls. The increasing prevalence of digital technologies (e.g., virtual reality, augmented reality, and photorealistic computer animation) has propagated discussions and citations of the "valley"; such conversation has enhanced the construct's verisimilitude. The uncanny valley hypothesis predicts that an entity appearing almost human will risk eliciting eerie feelings in viewers.