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Tuesday, August 13, 2013

Regaining childhood with virtual reality

Variations of the rubber hand illusion have been used in a range of different experiments. But can you use it to give someone a complete body make over? Domna Banakou, Raphaela Groten and Mel Slater from the University of Barcelona show that you can. They used immersive virtual reality (IVR) to turn adults into children.

The authors used IVR to convince 30 adults that they had the body of either a four year old child or of an adult that was scaled down to child-size. Half the time, the virtual body moved synchronously with the volunteer’s body, increasing the illusion of having ownership of that body. In other cases, the virtual body’s movements were disconnected from that of the test subject. You can see an example below:

Okay, that didn't look all that convincing. But I'm sure it's different when you're wearing the suit yourself. And in fact, participants did claim to feel personal ownership of their virtual bodies. This was equally true whether that virtual body was that of a child or a tiny adult. However, they overestimated the size of objects (as indicated by holding their hands apart a corresponding distance) more when embodying children’s bodies than when their virtual bodies were small adults. Remember both bodies were the same size, they just had different proportions. 

Subjects were also quicker to associate themselves with child-like qualities when they embodied the four year old body, based on implicit association tests. Thus, not only did the participants perceive their environment as if they were really small children, they even reacted like children. 

These perceptions disappeared when the movements of the virtual body were asynchronous from the subject’s body. In those experiments, the child’s body and the small adult body were equivalent.

It’s amazing how much we rely on external clues to figure out not only our place in the world, but who we are. For better or worse, people really can be tricked into thinking they’re someone else. This may bode well for humans when we start installing our brains into robot bodies. 

Domna Banakou, Raphaela Groten, & Mel Slater (2013). Illusory ownership of a virtual child body causes overestimation of object sizes and implicit attitude changes Proceedings of the National Academy of Sciences of the United States of America DOI: 10.1073/pnas.1306779110.