Rubber arm
As well as creating a sensation that a missing limb is present, the human brain can be fooled into thinking that an inanimate object is part of the body. If a subject's hand is hidden and a rubber hand placed in view, simultaneously stroking the hidden hand and the rubber hand conjures up a sense that the rubber hand is part of the body.
What's more, threatening the rubber hand - with a sharp implement - elicits a feeling of anxiety and a desire to move the hand away from the threat. The results suggest that artificial limbs could be made to feel as if they were a genuine part of the body, providing input beyond simple propioceptor-like positional information or a sense of touch. This feeling of ownership is also linked to activity in the interoceptive areas of the brain.
Researchers have also managed to take this a step further and create an illusion that a subject's entire body is located elsewhere - a true 'out of body' experience. In one experiment, subjects were given a video headset so that they could see a view of their back. An experimenter rubbed their chests with a rod, but subjects could only see a rod situated behind them. This created the illusion that they were situated behind their own body - they could even see themselves yet had no sense that their body was actually 'them'.
Image: Artificial arm; Wellcome Images