La ilusión de poseer tres brazos/ L'illusion de posséder trois bras (anglais-ingles)

... represents a major advance because it challenges the traditional view of the gross morphology of the human body as a fundamental constraint on what we can come to experience as our physical self, by showing that the body representation can easily be updated to incorporate an additional limb.

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0017208