Uncanny valley
The uncanny valley describes an emotional relationship between a human being and a robot or simulation with regard to aesthetics and likeability. It refers to the unsettled feeling many people encounter when seeing a human-like figure with a certain degree of realism.
More plainly, as human simulation begins to look more like actual people, there is a point where their appearance quickly turns from favorable to revulsive. It should be noted that animation (movement) of any kind amplifies this response.
The uncanny valley is experienced in many areas, including 3-D animation, toys, robotics, and animatronics.
Uncanny valley explained
The following graph is a visual example of the uncanny valley. Moving left to right, a certain degree of realism is pleasing to most individuals as it adds relatability to an inhuman figure. However, past a certain point, there is a steep dropoff where robots become "uncomfortably" realistic. This uneasiness is usually calmed once the figure reaches a point where it's indistinguishable from a person, hence the "valley" part of the term.
