Yesterday I had a good discussion with Xavier Décoret (from INRIA-ARTIS) about the Uncanny Valley phenomenon. It's a a concept coined by japanese roboticist Doctor Masahiro Mori well described in this paper: The Uncanny Valley: Why are monster-movie zombies so horrifying and talking animals so fascinating? by Dave Bryant:

Though originally intended to provide an insight into human psychological reaction to robotic design, the concept expressed by this phrase is equally applicable to interactions with nearly any nonhuman entity. Stated simply, the idea is that if one were to plot emotional response against similarity to human appearance and movement, the curve is not a sure, steady upward trend. Instead, there is a peak shortly before one reaches a completely human “look” . . . but then a deep chasm plunges below neutrality into a strongly negative response before rebounding to a second peak where resemblance to humanity is complete.

This chasm—the uncanny valley of Doctor Mori’s thesis—represents the point at which a person observing the creature or object in question sees something that is nearly human, but just enough off-kilter to seem eerie or disquieting.

More about it:

Mori, Masahiro (1970). Bukimi no tani [the uncanny valley]. Energy, 7, 33–35.
Mori, Masahiro (1982). The Buddha in the Robot. Charles E. Tuttle Co.

This has also been studies in cognitive sciences: MacDorman, Karl F. (2005). Androids as an experimental apparatus: Why is there an uncanny valley and can we exploit it? , in Proceedings of CogSci-2005 Workshop: Toward Social Mechanisms of Android Science, 106-118.

Why do I blog this? This phenomenon is very interesting in terms of the consequences for practitioners like interaction designers and is a pertinent example of how some cognitive aspects could impact design.