One person in ten is thought to have undergone an out-of-body experience during their life. Such events, where a person observes him- or herself as if from outside of the physical body, are often associated with traumatic experiences or with situations where brain function is compromised, such as epilepsy or stroke.

Dr Henrik Ehrsson, then working at the Wellcome Trust Centre for Neuroimaging in London, used a video system to re-create out-of-body experiences in the lab. Subjects watched head-mounted screens that showed them a live film of the back of their body, from the perspective of someone sitting behind them.

The researchers then used two plastic rods to simultaneously touch the subject's real chest (which was out of view of the camera) and the chest of the illusory body, moving this second rod towards where the illusory chest would be located, just below the camera's view. This triggered an out-of-body experience in the subjects, who reported that they had experienced sitting behind their own body.

When the illusory body was placed under threat, the participants' physiological responses (skin perspiration) showed that they perceived this threat as real.

Researchers hope that this kind of experiment will help to uncover the mechanisms behind why we associate our sense of 'self' so closely with our physical bodies.

This research was funded in part by the Wellcome Trust.

Image credit: Digital artwork exploring identity by Shelley James, Wellcome Images

External links

• Ehrsson HH. The experimental induction of out-of-body experiences. Science 2007;317(5841):1048.