Sigmund Freud came up with the idea of the uncanny in 1919. The uncanny is a specific emotion of fear we experience, when something isn’t quite as it should be. Freud especially talked about the uncanny in relation to animate objects.
In 1970, roboticist Mori warned that robots could indeed also provoke these negative feelings of unease, if they appeared too human. Based on these findings, Mori introduced the theory of the uncanny valley, depicting a drop of attraction towards the animate object, after it achieved human features. This unsettling feeling will – according to Mori – only disappear when the robot is completely indistinguishable to a human being.