On the face of it, toys really should not be creepy at all. Most folks would probably agree that playthings for children should, on average, be cute and inoffensive. However, toymakers also have to deal with the unfortunate reality that the items they make tend to be human or humanoid forms and, as it turns out, people have a weird aversion to this concept.

This is generally referred to as the uncanny valley, where “mostly” human figures make people nervous. We tend to be able to relate more to forms and figures that resemble us, but as these figures get closer and closer to perfectly resembling humans, there is a “drop,” or a valley which suddenly creates some revulsion.

Some have, rather sensationally, suggested that this powerful aversion to “almost human” figures is some evolutionary response to alien doppelgangers. However, there is a significantly more logical explanation. It's the same reason rotten food, maggots and skeletons all, generally cause some degree of fear and disgust: being around dead things can be dangerous, and a corpse is perfectly in line with something “almost human.”

In toys, the uncanny valley tends to show up most often in hyper realistic baby dolls. While it might not be as common of a toy anymore, there was a period of time when dollmakers were going through a sort of arms race to produce baby dolls. This included features like crying until it was “fed,” the ability to urinate and dynamic sounds, from sleeping to laughter.

At a young age, this might all seem quite cool but as an adult, a very lifelike toy making noises and sometimes even “reacting” to movement and light (these sorts of features also exist) are probably the inspiration for horror movies about dolls and toys coming to life.