Recent trends show digital devices utilized with increasing frequency in most crimes committed. Investigating crime involving these devices is labor-intensive for the practitioner applying digital forensics tools that present possible evidence with results displayed in tabular lists for manual review. This research investigates how enhanced digital forensics tool interface visualization techniques can be shown to improve the investigator's cognitive capacities to discover criminal evidence more efficiently. This paper presents visualization graphs and contrasts their properties with the outputs of The Sleuth Kit (TSK) digital forensic program. Exhibited is the textual-based interface proving the effectiveness of enhanced data presentation. Further demonstrated is the potential of the computer interface to present to the digital forensic practitioner an abstract, graphic view of an entire dataset of computer files. Enhanced interface design of digital forensic tools means more rapidly linking suspicious evidence to a perpetrator. Introduced in this study is a mixed methodology of ethnography and cognitive load measures. Ethnographically defined tasks developed from the interviews of digital forensics subject matter experts (SME) shape the context for cognitive measures. Cognitive load testing of digital forensics first-responders utilizing both a textual-based and visualized-based application established a quantitative mean of the mental workload during operation of the applications under test. A t-test correlating the dependent samples' mean tested for the null hypothesis of less than a significant value between the applications' comparative workloads of the operators. Results of the study indicate a significant value, affirming the hypothesis that a visualized application would reduce the cognitive workload of the first-responder analyst. With the supported hypothesis, this work contributes to the body of knowledge by validating a method of measurement and by providing empirical evidence that the use of the visualized digital forensics interface will provide a more efficient performance by the analyst, saving labor costs and compressing time required for the discovery phase of a digital investigation.

Encephalogram (EEG) devices are one of the active research areas in human-computer interaction (HCI). They provide a unique brain-machine interface (BMI) for interacting with a growing number of applications. EEG devices interface with computational systems, including traditional desktop computers and more recently mobile devices. These computational systems can be targeted by malicious users. There is clearly an opportunity to leverage EEG capabilities for increasing the efficiency of access control mechanisms, which are the first line of defense in any computational system. Access control mechanisms rely on a number of authenticators, including “what you know”, “what you have”, and “what you are”. The “what you are” authenticator, formally known as a biometrics authenticator, is increasingly gaining acceptance. It uses an individual’s unique features such as fingerprints and facial images to properly authenticate users. An emerging approach in physiological biometrics is cognitive biometrics, which measures brain’s response to stimuli. These stimuli can be measured by a number of devices, including EEG systems. This work shows an approach to authenticate users interacting with their computational devices through the use of EEG devices. The results demonstrate the feasibility of using a unique hard-to-forge trait as an absolute biometrics authenticator by exploiting the signals generated by different areas of the brain when exposed to visual stimuli. The outcome of this research highlights the importance of the prefrontal cortex and temporal lobes to capture unique responses to images that trigger emotional responses. Additionally, the utilization of logarithmic band power processing combined with LDA as the machine learning algorithm provides higher accuracy when compared against common spatial patterns or windowed means processing in combination with GMM and SVM machine learning algorithms. These results continue to validate the value of logarithmic band power processing and LDA when applied to oscillatory processes.

This thesis presents a series of studies to explore and understand the design of eyes-free interfaces for mobile devices. The motivation is to devise a holistic design concept that is based on the WIMP paradigm and is adapted to the requirements of mobile user interaction. It is proposed that audio is a very efficient and effective modality for use in an eyes-free mobile interface. Methods to transfer the WIMP paradigm to eyes-free interfaces are proposed and evaluated. Guidelines for the implementation of the paradigm are given and – by means of an example – a holistic design concept is proposed. This thesis begins with an introduction to and critical reflection of re- currently important themes and research methods from the disciplines of psychoacoustics, psychology, and presence research. An overview of related work is given, paying particular attention to the use of interface metaphors in mobile eyes-free interfaces. The notion of distance is discussed as a method to prioritise, structure, and manage attention in eyes-free interfaces. Practical issues arising from sources becoming inaudible with increasing distance can be addressed by proposing a method modeled on echo location. This method was compared to verbally coded distance information and proved useful for identifying the closest of several objects, while verbally coded distance infor- mation was found to be more efficient for identifying the precise distance of an object. The knowledge gained from the study can contribute to improv- ing other applications, such as GPS based navigation. Furthermore, the issue of gaining an overview of accessible objects by means of sound was exam- ined. The results showed that a minimum of 200 ms between adjacent sound samples should be adhered to. Based on these findings, both earcons and synthesized speech are recommendable, although speech has the advantage of being more flexible and easier to learn. Monophonic reproduction yields comparable results to spatial reproduction. However, spatial reproduction has the additional benefit of indicating an item’s position. These results are transferable and generally relevant for the use of audio in HCI. Tactile interaction techniques were explored as a means to interact with an auditory interface and were found to be both effective and enjoyable. One of the more general observations was that 2D and 3D gestures were intuitively used by participants, who transferred their knowledge of established gestures to auditory interfaces. It was also found that participants often used 2D ges- tures to select an item and proceeded to manipulate it with a 3D gesture. The results suggest the use of a small gesture set with reversible gestures for do/undo-type actions, which was further explored in a follow up study. It could be shown that simple 3D gestures are a viable way of manipulating spatialized sound sources in a complex 3D auditory display. While the main contribution of this thesis lies in the area of HCI, pre- viously unresearched issues from adjacent disciplines that impact the user experience of auditory interfaces have been addressed. It was found that regular, predictable movement patterns in 3D audio spaces cause symptoms of simulator sickness. However, these were found to be minor and only oc- curred under extreme conditions. Additionally, the influence of the audio reproduction method on the perception of presence, social presence, and realism was examined. It was found that both stereophonic and binaural reproduction have advantages over monophonic sound reproduction: stereo- phonic sound increases the perception of social presence while binaural sound increases the feeling of being present in a virtual environment. The results are important contributions insofar as one of the main applications of mobile devices is voice based communication; it is reasonable to assume that there will be an increase in real-time voice based social and cooperative networking applications. This thesis concludes with a conceptual design of a system called “Foogue”, which uses the results of the previous experiments as the basis of an eyes-free interface that utilizes spatial audio and gesture input.

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Despite two decades of empirical studies focusing on programmers and the problems with programming, usability of textual programming languages is still hard to achieve. Its younger relation, visual programming languages (VPLs) also share the same problem of poor usability. This research explores and investigates the usability issues relating to VPLs in order to suggest a set of design principles that emphasise usability. The approach adopted focuses on issues arising from the interaction and communication between the human (programmers), the computer (user interface), and the program. Being exploratory in nature, this PhD reviews the literature as a starting point for stimulating and developing research questions and hypotheses that experimental studies were conducted to investigate. However, the literature alone cannot provide a fully comprehensive list of possible usability problems in VPLs so that design principles can be confidently recommended. A commercial VPL was, therefore, holistically evaluated and a comprehensive list of usability problems was obtained from the research. Six empirical studies employing both quantitative and qualitative methodology were undertaken as dictated by the nature of the research. Five of these were controlled experiments and one was qualitative-naturalistic. The experiments studied the effect of a programming paradigm and of representation of program flow on novices' performances. The results indicated superiority of control-flow programs in relation to data-flow programs; a control-flow preference among novices; and in addition that directional representation does not affect performance while traversal direction does - due to cognitive demands imposed upon programmers. Results of the qualitative study included a list of 145 usability problems and these were further categorised into ten problem areas. These findings were integrated with other analytical work based upon the review of the literature in a structured fashion to form a checklist and a set of design principles for VPLs that are empirically grounded and evaluated against existing research in the literature. Furthermore, an extended framework for Cognitive Dimensions of Notations is also discussed and proposed as an evaluation method for diagrammatic VPLs on the basis of the qualitative study. The above consists of the major findings and deliverables of this research. Nevertheless, there are several other findings identified on the basis of the substantial amount of data obtained in the series of experiments carried out, which have made a novel contribution to knowledge in the fields of Human-Computer Interaction, Psychology of Programming, and Visual Programming Languages.

The main objective of the research described in this thesis was to investigate and understand the origins of culturally-determined usability problems in the context of Human Computer Interaction (HCI) to develop a method for treating this issue, when designing systems intended to be shared by culturally-heterogeneous user groups, such as Computer Supported Co-operative Work (CSCW) systems and the Internet. The resulting approach supports HCI designers by providing an alternative to internationalisation and localisation guidelines, which are inappropriate for tackling culturally-determined usability problems in the context of shared-systems. The research also sought to apply and test the developed approach in order to assess its efficacy and to modify or improve it accordingly.

Visualization tools are frequently used to help people understand everyday data in their lives. One such example is visualization in behaviour feedback tools. Behaviour feedback tools are used to try to help people improve their health or personal well-being or to carry out sound environmental sustainability practices. However, understanding and reasoning about personal data (e.g., pedometer counts, blood pressure readings or home electricity consumption) or gaining a deeper understanding of one's current practices and learning how to make a change can be challenging when using data alone. My literature review of this field showed that two of the main challenges in actual practice are providing a context in which to reason about the data and reducing the cost of maintenance to fit those tools into everyday life routines. Thus, I propose to integrate time-varying feedback data within a personal digital calendar. This combination of calendar and feedback data can provide contextual information to interpret data and make the data accessible in an attentionally ambient way that is suitable for maintaining awareness. I propose that the familiarity and common practice of using digital calendars can minimize the cost of learning and maintenance for people and easily fit into one's daily life routines. The viability of this approach was confirmed in my quantitative lab experiments. The results showed that visualization of feedback data integrated on a digital calendar is comprehensible, and it does not interfere with regular calendar use with proper visual encodings. After confirming the viability of my proposal, I implemented the on-calendar visualization as a web application that was synchronized with Google Calendar API and a real-time feedback data stream. To further investigate this approach in a real life situation, I deployed the application in the field for longitudinal field studies: two case studies as pilot deployment and an eight-week field study. Results showed that people liked the idea of integrating feedback data into their personal digital calendars. It required a low cost in learning and maintenance. The calendar events provided rich context for people to visualize and reason about their feedback data. The design enabled people to quickly identify and explain repeated patterns and anomalies. Meanwhile, I found that people's existing information use habits (in this case, how they use digital calendars) can highly influence the effectiveness of the feedback design. Moreover, I derived a feedback model that identifies basic components in feedback design and illustrates the role of feedback tools. With that I articulated possible design barriers that could prevent ongoing use of feedback tools. Reflecting on the effects of the on-calendar design approach, I discussed design implications inspired by this work. This work introduces a reflective approach in feedback design that can easily fit into people's existing information ecosystem (specifically, a personal digital calendar in this work). The main contributions of this thesis are: the first systematic literature review of personal visualization design used in everyday life; the design and implementation of an on-calendar design that integrates feedback data on people's personal digital calendars to provide context for reasoning and support easy access for ongoing use; the extended definition of ambience from spatial location to attentional demand; a viability study to confirm the on-calendar design approach; longitudinal studies to investigate the effects of the on-calendar design approach and the feedback model of design mechanism to inspect ongoing factors in feedback designs. / Graduate / 0984, 0384 / dhuangca@gmail.com

This study presents a way to design a visualization method in a geographic information system for complex electronic warfare assessment. Enhanced usability was in focus and the work covers important factors and challenges when evaluating usability during the development process in a complex domain.   Electronic warfare is an important part of each country’s defence. Assessing Electronic Warfare capabilities in real war zones is normally impossible, making simulations and visualizations important parts of the process. The field of visualization covers visual techniques for presenting large data sets in ways that provide insight to the user. In a visualization, an enhanced usability is achieved with a user-centered interface. Developing a visualization towards usability has its challenges, to develop it in a complex domain with few domain experts as users is even more challenging.   The study used an iterative method with three iterations of implementation and evaluation, applying an approach adapted for experts working in a complex domain. When designing a visualization for a complex domain, the most important factors during the design process are to understand how the users work in the system and to make the visualization simple and over-intuitive.   The last user testing indicated that the users were able to draw conclusions about high-level conceptual goals based on the visual representation as well as to use the GUI to interact with the system. The result of this study is a visualization method for radar propagation with local refractive index, together with a process that can be used to design and evaluate a visualization method towards usability in a complex domain.

Nowadays, increasing numbers of people do travel research on their smartphones. More precisely, digital maps provide locational information, which is important during the planning process. However, smartphones are restricted by their small screen size, resulting in fragmented information delivery; also, the design of digital maps lacks features. The aims of this study are to investigate users’ travel-planning behavior on smartphones, identify the pain points and missing contexts when using digital maps on smartphones, and provide design guidelines for future digital map design. The study was done by conducting a travel-planning activity and a codesign workshop to bring users into the design process, promote in-depth discussion, and explore a new design possibility for digital maps with users. The results showed that people’s goals when planning travel include reducing their workload, improving effectiveness, and ensuring flexibility. People use digital maps to support not only information searching but also information compiling, including saving locations and routes. In addition, several difficulties have been pointed out: cross-platform planning, information hierarchy, and retrieval on digital maps.

<p>The studio model of education incorporated in to many design-oriented HCI programs in the past two decades brings a number of objectives to programs implementing it. One objective is the building of a “bridge” between pedagogy and practice, preparing students for the differing realities between academia, and the constraints imposed in an organizational setting. The bridge also encourages the development of a student’s design philosophy, allowing them to acknowledge and understand their conceptions of design which influence decisions in project-processes, and the projected communities they may navigate towards in practice. This study addresses the dimensions of design philosophy held by students educated in these programs, and how such philosophies are engaged and shaped further in practice. Through a qualitative interview approach, this study presents 9 dimensions of design philosophy through the accounts of 10 students and practitioners, reflecting on their education and practice. Using existing work studying the flow of competence between practitioners and organizations, the discussion of the dimensions presented provides four ways in which the philosophies of practitioners may encounter tensions in practice. This research proposes future work on how the studio model in HCI pedagogy may better prepare students for enacting their philosophies, and further reflecting on the shaping of that philosophy through felt contrasts between education and practice. </p>