OUT-OF-BODY IN VIRTUAL REALITY
Can you imagine becoming convinced that a pink, rubber hand is your own? Unlikely as it seems, this is the famous ‘rubber hand illusion’. The person’s own hand, lying next to a rubber hand, is concealed from view by a screen. If both hands are stroked simultaneously, people start to feel the touch as though it is on the rubber hand.
Bigna Lenggenhager, at the University of Zurich, has managed to create a ‘whole body illusion’ using virtual reality. She places a camera two metres behind a participant and gives them a head-mounted display to wear, so they are looking at their own back. When the experimenter gently strokes the participant’s back, they can watch as well as feel it. Gradually the sensation shifts towards the virtual body.
In Sweden, neuroscientist Henrik Ehrsson uses a different method to create a similar effect. A camera is again positioned two metres behind a participant, but this time their chest is stroked in synchrony with a stick moving up and down in front of the cameras. With this method, people feel they have moved backwards towards the cameras. These may just be tricks but their effect can be profound. When the illusion is strong, body temperature drops, pain is felt less intensely, and threatening the real body with a knife produces a weaker reaction. The illusions have been induced inside an fMRI scanner, revealing that changes in activity in the brain’s temporoparietal junction reflect changes in self-location. These illusions are not the same as full OBEs, yet they reveal how our sense of being inside our own body can be manipulated. And this may explain how we can sometimes be convinced that we are outside our body.
“It may turn out that OBEs are linked with the important social skill of being able to understand someone else’s perspective”
group of patients with schizophrenia to a control group and although the schizophrenics reported more bizarre experiences of various kinds, the two groups included the same number of OBErs.
A more positive way to understand OBEs fuels a recent debate between those who think they represent a failure and others who say they reveal a skill. The earliest psychological theories suggested that imagery might be the relevant skill but many experiments showed no obvious differences in richness or vividness of imagery. Some small differences were found in the ability to switch viewpoints, for example between imagining a scene from eye level or from a bird’s eye view, and OBErs were found more often to dream in bird’s eye view. These were clues leading to recent research showing the relevance of what is called ‘perspective taking’. This is the ability to see things from someone else’s point of view and is related to empathy. Interestingly, this ability also depends on areas of the brain close to the TPJ. So it may turn out that OBEs, far from being a failure, are linked with the important social skill of being able to understand someone else’s perspective.
It is still early days for serious OBE research but now it has begun we may find that an experience that was once dismissed as fantasy and ignored by mainstream science is now contributing to our understanding of consciousness and the nature of self.
LEFT: Experiments with cameras and headsets have allowed scientists to manipulate our sense of location
RIGHT: The brain’s temporoparietal junction (highlighted with a black circle) is the region that seems to be associated with OBEs