A research, recently published on the journal Proceedings of the National Academy of Sciences, suggests that a correlate of a body-ownership illusion is that the virtual type of body carries with it a set of temporary changes in perception and behaviours that are appropriate to that type of body. The research has been carried out by Domma Banakou, Raphaela Groten and Mel Slater, experts from the Experimental Virtual Environments Lab for Neuroscience and Technology (Event Lab) at the Faculty of Psychology of the UB.
An illusory sensation of ownership over a surrogate limb or whole body can be induced through specific forms of multisensory stimulation, such as synchronous visual-tactile tapping on the hidden real and visible rubber hand in the phenomenon so-called 'rubber hand illusion'. Such methods have been used to induce ownership over a manikin and a virtual body that substitute the real body, as seen from first-person perspective, through a head-mounted display. However, the perceptual and behavioural consequences of such transformed body ownership have hardly been explored.
Researchers developed two experiments. In the first one, immersive virtual reality was used to embody 30 adults as 4-year-old children (condition C), and as an adult body scaled to the same height as the child (condition A), experienced from the first-person perspective, and with virtual and real body movements synchronized. The result was a strong body-ownership illusion equally for C and A. Moreover, there was an overestimation of the sizes of objects compared with a non-embodied baseline, which was significantly greater for C compared with A. An implicit association test showed that C resulted in significantly faster reaction times for the classification of self with child-like compared with adult-like attributes.
In the second experiment, extended to 16 new participants, he ownership illusion was extinguished by using visuomotor asynchrony, with all else equal. The size-estimation and implicit association test differences between C and A were also extinguished.
Both experiments confirm that altered bodily self-representation can have a spontaneous and significant influence on aspects of perception and behaviour. It has been shown that IVR supports global scaling of sizes, where the brain automatically adjusts for the overall size of one's avatar, which is in line with past studies. Most importantly, our system can reproduce the experience of the world "as a child experiences it," and not only as a simple linear transformation of size.
Furthermore, a demonstration that avatars can change perception of our selves has great potential in various applications and for the interaction between participants. Finally, and importantly, it is worth pointing out that as we choose our self-representations in virtual reality settings, our behaviours may be shaped accordingly; it is therefore not only the influence that users exert on avatars, but essentially the impact of avatars on their users and how they can shape their attitudes.
- D. Banakou, R. Groten, M. Slater. Illusory ownership of a virtual child body causes overestimation of object sizes and implicit attitude changes. Proceedings of the National Academy of Sciences, 2013; DOI: 10.1073/pnas.1306779110
Cite This Page: