Remember the uncanny valley
? Monkey's have it too:
New findings published in PNAS this September are putting some long-overdue experimental rigor behind the uncanny valley. Last spring at Princeton’s Neuroscience Institute, Asif Ghazanfar developed a computer model of a macaque monkey designed to interact with real macaques. But the monkeys weren’t fooled. Further testing revealed that, much to Ghazanfar’s surprise, his model was eliciting an uncanny valley response from the monkeys. It was the first time scientists had ever observed such a response in a non-human species.The article
is a pretty good history of the notion of the uncanny valley and various explanations for it. I didn't know Freud wrote about the uncanny, but it's not surprising.