Designing for Hand Ownership in Interaction with Virtual and Augmented Reality

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This thesis explores the body ownership illusion during interaction in virtual
and augmented reality; in particular, how the body ownership illusion can
be leveraged to overcome the limitations of our physical bodies and to create
more efficient and engaging interactions. Body ownership is the feeling that
we inhabit a physical body through which we experience and interact with the
world. The conviction that your physical hand is, in fact, your own hand is
an example of body ownership. Under certain conditions, this feeling can also
be elicited by an artificial body or body part (e.g., a rubber hand or virtual
hand), which is then known as the body ownership illusion.
The research questions presented in this thesis were explored with two independent
prototypes: the first consisting of an augmented reality system
and the second providing a virtual reality experience. The state-of-the-art for
immersive virtual reality involves interaction with the virtual world through
controllers which we perceive as tools hovering in mid-air. We cannot see our
hands gripping these tools, nor do we have any other indicators of our body
in our peripheral vision or through the presence of shadows. This ghostly,
body-less state is unnatural, and a constant reminder that the world we see
around us is not real. Our sense of presence is limited if we do not have a
body that inhabits part of the environment we perceive. In augmented reality
applications on the other hand, we typically perceive our own body as part of
the real world and can sometimes use our physical hands to manipulate virtual
content. However, in contrast to virtual hands, our physical hands cannot
be flexibly adapted for a specific task (e.g., to extend our reach). Hence, I
explored how we can create a virtual body representation to which the user
feels strongly connected through the body ownership illusion. I argue that
this inherently changes the quality of the interaction; while traditionally the
screen forms a clear boundary between the real and the virtual world, the
illusion of owning a virtual body moves this border into our own minds. In
other words, a virtual body representation may seem just as real to us as our
physical bodies.
The findings presented in this thesis show that we can control an unnaturally
long virtual arm that we perceive as part of our body. Furthermore, we can
feel body ownership of a virtual hand that appears to be reaching towards
an overhead target, while our physical hand rests comfortably at waist-level.
We may even feel body ownership of a very unrealistic, disconnected virtual
hand, if it follows our movements naturally. The results thus indicate that
our mental body representation may be more malleable than was previously
believed. Consequently, while most approaches to interaction design attempt
to modify the virtual world or tools with which we interact, we can instead
augment the body we interact through - or at least our mental image thereof.
Original languageEnglish
Place of publicationAarhus
PublisherAarhus Universitet
Number of pages193
Publication statusPublished - 29 Oct 2018

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