Children’s Embodiment of Virtual Avatars and The Developing Structural Body Image

Abstract

This thesis presents two strands of work to investigate how children understand their own bodies. First, we investigate the sense of embodiment – the feeling of owning and controlling one’s own body. This can be experimentally tested in a paradigm known as the full-body illusion, which uses immersive virtual reality avatars with motion-tracked full-body motor control to trigger a salient feeling of embodiment over an avatar. Using this, previous studies have manipulated the visual form of virtual avatars to study the role of body form in embodiment. Second, we measure structural body representation with a body-part-location pointing task, with which previous research has revealed that adults’ representations are subject to error and distortion. Using virtual embodiment and structural body representation tasks with the same participants, we ask how these constructs develop alone and interactively in the developing child – for whom they are made incredibly complex by constant sensorimotor growth and change. Specifically, in 5- to 10-year-old children we measure children’s ownership and agency responses to four avatars with systematically manipulated structural and material form; and have children point to a series of body part locations to assess their structural representation. We find that children have strict limits on their embodiment of distorted avatars, and are able to selectively embody some material and/or structural distortions more than others; as well as that avatar form can influence changes in children’s exploratory motor behaviour. Children also possess striking distortions in the accuracy of their perceived body part lengths and widths across numerous torso, upper, and lower body locations – with shoulder width error significantly decreasing with age. However, structural body representation error does not determine avatar embodiment, which is better predicted by a measure of how functionally useful children feel the avatar is. The findings of this project imply that children aged 5-10 years possess a complex embodiment system that is somewhat nuanced in its response to subtle changes in material and structural avatar form, but is ultimately under strictly controlled limits; and that this develops distinctly to children’s structural whole-body representations, which are greatly distorted in their accuracy and have much development left to occur beyond 10 years old.