This refers to the feeling of revulsion that many human beings feel when they interact with humanoid robots that are designed to closely resemble them. The feeling of unease is linked to the unrealistic nature of such robots which fail to perfectly ape the physical and behavioural characteristics of human beings. It is believed that the revulsion may be a natural reaction of the human brain in order to avoid unsuitable mates. Robots that can look and behave perfectly like human beings, however, may not cause unsettling feelings in human beings that interact with them. The idea was proposed in a 1970 article by Japanese roboticist Masahiro Mori.