REBOOTING PERCEPTION
Slater defines consequences of ‘body ownership’ in VR
BY JULIETTE LORD
their own by participants, with significant What constitutes the body and where applications in VR (Virtual Reality) training, limb prosthetics, and entertainment.” it begins and ends may seem obvious. MANIERA discussed with one of the However over the last 25 years research authors, Mel Slater, what the consequencsuggests the brain can be convinced that stimuli applied to something “outside” the es of “body ownership illusions” actually are. body is actually felt by the body itself. Firstly, what do we mean when we This theory was tested in the so called refer to a virtual body? In the research, a ‘Rubber Hand’ experiment conducted virtual body is one that is seen to replace initially in 1998 by Matthew Botvinick the real body. Wearing a wide field-ofand Jonathan Cohen. When a person’s view head mounted display through real hand is placed out of view and a viswhich you see virtual scenes in stereo, the ible fake hand is repeatedly stroked and image is updated to see the correct part tapped in synchrony with the unseen of the scene when you turn your head, in hand, subjects report a strong sense in the same way when we turn our head in which the fake hand is experienced as real life new parts of the scene come into part of their own body. Further studies view, and other parts of the scene go out arrive at similar conclusions but using a of view. When you look down at your virtual environment, instead of a rubber real life body in virtual reality, the same hand. One such study Towards a Digital situation can be programmed so that a Body: The Virtual Arm Illusion Slater, virtual body can be displayed where the Perez-Marcos, Ehrsson and Sanchezreal body is located. In addition, a motion Vives (2008) concluded self-representacapture suit is worn so that the computer tion and body images problems can be program can continuously update the transformed. posture of your virtual body to make it “Virtual reality offers the possibility for a highly flexible approach to the prob- match that of your real body. So in real time, as you move, the virtual body can lem of body image and self- representabe programmed to move the same. tion, and the conditions under which it “These two features, seeing the vircan be transformed,” the report stated. tual body as you would your real body ... “For the future our work also suggests and making the virtual body’s movement that people can have their ‘self ’ enter the match your real movements can give a virtual domain in a genuine sense of the very strong perceptual illusion that it is word, and not just metaphorically as in your body,” Slater said. “Of course you current day computer games and online know it isn’t, but I’m talking about a fast communities. In combination with BCI brain response, that quickly generates the (Brain Computer Interface) we envisage illusion that the virtual body you see must a functioning virtual body that is felt as
78 | MANIERA | mymaniera.com JULY 2013