In this research I investigate the design and use of virtual avatars (full body representations of the user) among older adults over 65 years old. This research seeks to understand the avatar's designs made by older adults in relation to the ageing body; and how the use of these self-representations impact older adults' experience when socializing online. This thesis firstly uses an exploratory approach to understand the current use of online self-representations among older adults, then design workshops to comprehend older adults' visual choices in relation to the design of humanoid avatars and finally a long-term user study where participants use and reiterate avatar designs through multiple virtual reality social sessions. This research will contribute to the understanding of how older adults use self-representations to connect with others in online environments while providing insights of how to expand character creation interfaces to cater visual preferences of those in older age.

The growth of commercial VR technology has fueled an interest in user embodiment, where a graphical representation of the user, a virtual avatar, enables a more immersive experience and richer interaction. Recent research suggests that older adults are increasingly playing digital games. These factors, combined with the rapidly ageing population, means it is vital that avatar creation software responds to the needs of older adults. Our study seeks to address these needs, by better understanding older adult opinions about virtual avatars that are photorealistic, i.e. bearing likeness to their physical appearances. In our exploratory study, we interviewed six older adults aged between 70 and 80 years and asked them to evaluate 18 photorealistic avatars created with three different commercial avatar creation tools. Results showed that participants were not satisfied with their custom-made avatars due to them missing characteristic features. The results also showed that there was major consensus towards using photorealistic avatars across a range of virtual environments.

Often, when analyzing the behaviour of systems modelled as context-free languages, we wish to know if two languages overlap. To this end, we present a class of semi-decision procedures for regular separability of context-free languages, based on counter-example guided abstraction refinement. We propose two effective instances of this approach, one that is complete but relatively expensive, and one that is inexpensive and sound, but for which we do not have a completeness proof. The complete method will prove disjointness whenever the input languages are regularly separable. Both methods will terminate whenever the input languages overlap. We provide an experimental evaluation of these procedures, and demonstrate their practicality on a range of verification and language-theoretic instances.

Virtual Avatars can bring opportunities for enjoyment, social participation and exploration of identities. However, the configuration of avatar creation software may marginalise some groups of users due to them reinforcing social stereotypes that privilege youth and beauty, rather than representing the broader variety of human identities. Older adults are one group who may be disadvantaged with respect to avatars as avatar studies have typically focused on younger users. Considering that older populations are growing and that their participation in virtual environments is increasing, it is timely to investigate older adults' preferences in relation to avatars. We conducted a study with 23 participants (70+ years old) to understand the representational requirements of older adults when creating a humanoid virtual avatar. Our findings demonstrate that older adults are negotiating ageing stereotypes when creating a virtual body. These negotiations of body appearances range from: the Actual Avatar that by mirroring the self suggests an acceptance of the ageing body; the Vibrant Avatar that is idealising the physical condition of the self; the Other Avatar, that aims to explore other identities; and the Companion Avatar that creates another persona as company. These findings highlight that older adults have specific representational requirements when designing virtual avatars.

Older adults are increasingly engaging in online activities, including games, with other people. Many online environments require the user to create some form of self-representation, ranging from a simple user name through to a full body avatar. These self-representations not only enable access to online activities, but also provide an opportunity for expressing both the real and ideal identity. We wanted to better understand the impacts of later life on the construction of self-representations when playing online games. Our study used gameplay observations and semi-structured interviews with 10 older adult gamers aged from 65 to 95 years. We found they designed their player self-representations to project aspects of their lost (former) self and to embrace their present older selves. This engagement with self-representations as a form of self-expression suggests that designers need to consider older gamers, and their diverse preferences, when creating tools for customizable self-representations in online games.

Gender equity is an issue of increasing importance in the technology industry generally and HCI specifically. Women are historically underrepresented at all levels, but moreso in senior roles; conversely visible senior women increase female participation generally. In this paper we present the first scientometric analysis of OzCHI examining the interaction between gender and role seniority, showing that overall female representation is quite good, but we need to be cautious to preserve it. This is the first analysis of this type to examine the issue of gender in any HCI venue.

While computers causing chaos is a common social trope, nearly the entirety of the history of computing is dedicated to generating order. Typical interactive information retrieval tasks ask computers to support the traversal and exploration of large, complex information spaces. The implicit assumption is that they are to support users in simplifying the complexity (i.e. in creating order from chaos). But for some types of task, particularly those that involve the creative application or synthesis of knowledge or the creation of new knowledge, this assumption may be incorrect. It is increasingly evident that perfect order-and the systems we create with it-support highly-structured information tasks well, but provide poor support for less-structured tasks. We need digital information environments that help create a little more chaos from order to spark creative thinking and knowledge creation. This paper argues for the need for information systems that offer what we term 'bounded chaos', and offers research directions that may support the creation of such interfaces.

There has been considerable hype about filter bubbles and echo chambers influencing the views of information consumers. The fear is that these technologies are undermining democracy by swaying opinion and creating an uninformed, polarised populace. The literature in this space is mostly techno-centric, addressing the impact of technology. In contrast, our work is the first research in the information interaction field to examine changing viewpoints from a human-centric perspective. It provides a new understanding of view change and how we might support informed, autonomous view change behaviour. We interviewed 18 participants about a self-identified change of view, and the information touchpoints they engaged with along the way. In this paper we present the information types and sources that informed changes of viewpoint, and the ways in which our participants interacted with that information. We describe our findings in the context of the techno-centric literature and suggest principles for designing digital information environments that support user autonomy and reflection in viewpoint formation.

Existing research into serendipitous information encountering has focused on how people stumble upon information, rather than how they create value from the information encountered. This online diary study with follow-up interviews provides an enriched understanding of the subjective value of information encounters and the motivators, barriers and actions involved in creating value from them. We leverage our findings to generate design suggestions for digital information tools aimed at assisting in creating value from encountered information.

Libraries increasingly offer much of their collection online, rendering it invisible or unavailable to readers who, for reasons of information experience, prefer to browse the shelves. Although the evidence that shelf browsing is an important part of information behavior is increasing, information browsing as a behavior is somewhat of a black box (in contrast to web browsing, which is relatively well understood). It seems likely from early work that browsing is not, in fact, a monolithic behavior, but rather a set of behaviors and goals. The typologies presented in these works, however, are of a too high level to offer much insight into what support is needed for successful online browsing. In contrast, a recent spate of speculative browsing technologies meet some browsing needs, but offer little theoretical understanding of how systems support browsing. The major contribution of this article is a new typology of library browsing behavior based on recent observations of browsing behavior in libraries. The secondary contribution is an understanding of the interface features that would support these types of information browsers in an online environment.

Group A Streptococcus (GAS) skin infections are caused by a diverse array of strain types and are highly prevalent in disadvantaged populations. The role of strain-specific immunity in preventing GAS infections is poorly understood, representing a critical knowledge gap in vaccine development. A recent GAS murine challenge study showed evidence that sterilising strain-specific and enduring immunity required two skin infections by the same GAS strain within three weeks. This mechanism of developing enduring immunity may be a significant impediment to the accumulation of immunity in populations. We used an agent-based mathematical model of GAS transmission to investigate the epidemiological consequences of enduring strain-specific immunity developing only after two infections with the same strain within a specified interval. Accounting for uncertainty when correlating murine timeframes to humans, we varied this maximum inter-infection interval from 3 to 420 weeks to assess its impact on prevalence and strain diversity, and considered additional scenarios where no maximum inter-infection interval was specified. Model outputs were compared with longitudinal GAS surveillance observations from northern Australia, a region with endemic infection. We also assessed the likely impact of a targeted strain-specific multivalent vaccine in this context. Our model produced patterns of transmission consistent with observations when the maximum inter-infection interval for developing enduring immunity was 19 weeks. Our vaccine analysis suggests that the leading multivalent GAS vaccine may have limited impact on the prevalence of GAS in populations in northern Australia if strain-specific immunity requires repeated episodes of infection. Our results suggest that observed GAS epidemiology from disease endemic settings is consistent with enduring strain-specific immunity being dependent on repeated infections with the same strain, and provide additional motivation for relevant human studies to confirm the human immune response to GAS skin infection.