2017

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https://diglib.eg.org/handle/10.2312/2631227

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Browsing 2017 by Subject "body ownership"

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    The Impact of Virtual Embodiment on Perception, Attitudes, and Behaviour
    (TDX (Tesis Doctorals en Xarxa), 2017-04-26) Banakou, Domna
    Over the past two decades extensive research in experimental psychology, cognitive neuroscience, and virtual reality has provided evidence for the malleability of our brain's body representation. It has been shown that a person's body can be substituted by a life-sized artificial one, resulting in a perceptual illusion of body ownership over the fake body. Interestingly, several studies have shown that when people are virtually represented with a body different to their own, they exhibit behaviours associated with attributes pertaining to that body. In the research described here we exploited Immersive Virtual Reality to induce body ownership illusions over distinct virtual bodies. We examined how an altered self-representation can influence one's self-perception, perception of the environment, and implicit biases. To this end, we carried out two experimental studies to investigate embodiment of adults in a child virtual body, and a different race virtual body. Moreover, we tested whether it is possible to induce illusory agency over specific actions that are not carried out by the participants themselves. In the Virtual Child Body study, we embodied adults both as a 4-year-old child, and as an adult scaled-down to the same height as the child. The results showed that embodiment in the child body led to a significant overestimation of object sizes, which was approximately double the overestimation of those embodied in the adult body. Moreover, embodiment in the child resulted in changes in implicit attitudes about the self towards being child-like. These findings were diminished under asynchronous visuomotor correlations, providing further proof for the importance of visuomotor contingencies in producing body ownership illusions. Our findings extend and enrich previous research, yielding additional evidence of the malleability of our body representation. In the Racial Bias study, we aimed to explore how the type of body can influence racial discrimination, by embodying white people in a black virtual body. Previous research has shown that this type of embodiment can lead to a reduction of implicit racial bias, but its long-term effects were unknown. Here we tested whether this reduction in implicit bias can (a) be replicated, (b) it can last for at least one week, and (c) it is enhanced by multiple exposures. Participants were immersed in a virtual scenario between one and three times, each separated by two days, and implicit bias was measured one week before their first exposure, and one week after their last. The results showed that implicit bias decreased more for those with the black virtual body than the white, even a week after their virtual exposure, and irrespective of the number of exposures. In the Illusory Speaking study, we explored the possibility of inducing illusory agency over an action that participants did not carry out themselves. We describe a set of experiments, where under appropriate sensorimotor contingencies, we induce a subjective illusion of agency over the participants' speaking virtual body, as if they had been themselves speaking. When participants were asked to speak after this exposure, they shifted the fundamental frequency of their utterances towards that of the stimulus voice of the virtual body. We argue that these findings can be reconciled with current theories of agency, provided that the critical role of both ownership and actual agency over the virtual body are taken into account. Overall, our studies expand previous evidence for the malleability of our body representation, demonstrating how it is possible to induce ownership illusions over a child body, a different race body, or even a speaking body. Notably, we provide evidence of how body ownership and agency over the virtual body result in powerful, lasting changes in perceptual and cognitive processing, having the potential of compelling applications in psychology and neuroscience.