Theses and Dissertations from UMD
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New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM
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Item Egocentric Vision in Assistive Technologies For and By the Blind(2022) Lee, Kyungjun; Kacorri, Hernisa; Computer Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Visual information in our surroundings, such as everyday objects and passersby, is often inaccessible to people who are blind. Cameras that leverage egocentric vision, in an attempt to approximate the visual field of the camera wearer, hold great promise for making the visual world more accessible for this population. Typically, such applications rely on pre-trained computer vision models and thus are limited. Moreover, as with any AI system that augments sensory abilities, conversations around ethical implications and privacy concerns lie at the core of their design and regulation. However, early efforts tend to decouple perspectives, considering only either those of the blind users or potential bystanders. In this dissertation, we revisit egocentric vision for the blind. Through a holistic approach, we examine the following dimensions: type of application (objects and passersby), camera form factor (handheld and wearable), user’s role (a passive consumer and an active director of technology), and privacy concerns (from both end-users and bystanders). Specifically, we propose to design egocentric vision models that capture blind users’ intent and are fine-tuned by the user in the context of object recognition. We seek to explore societal issues that AI-powered cameras may lead to, considering perspectives from both blind users and nearby people whose faces or objects might be captured by the cameras. Last, we investigate interactions and perceptions across different camera form factors to reveal design implications for future work.Item Revealing Perceptual Proxies in Comparative Data Visualization(2021) Ondov, Brian David; Elmqvist, Niklas; Computer Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Data Visualization has long been shaped by empirical evidence of the efficacies of different encodings, such as length, position, or area, in conveying quantities. Less is known, however, about what may affect comparison of multiple data series, which generally involves extraction of higher-order values, such as means, ranges, and correlations. In this work, we investigate such factors and the underlying visual processes that may account for them. We begin with a case study motivating the research, in which we modify Krona, a Bioinformatics visualization system, to support several types of comparison. Next, we empirically examine the influence of “arrangement”—that is, whether charts are shown side-by-side, stacked vertically, overlaid, etc.—on comparative tasks, in a series of psychophysical experiments. The results suggest a complex interaction of factors, with different comparative arrangements providing benefits for different combinations of tasks and encodings. For example, overlaid charts make detecting differences easier but comparing means or ranges more difficult. While these results offer some guidance to designers, the number of interactions makes it infeasible to provide broad rankings of arrangements, as has been done previously for encodings. Our subsequent efforts thus work toward understanding the visual processes that underlie the extraction of statistical summaries needed for comparison. It has recently been proposed that simpler shortcuts, called Perceptual Proxies, are used by the visual system to estimate these values. We investigate proxies for bar charts in experiments using an “adversarial” framework, in which the ranking of two charts along a task metric (e.g. mean) is opposite their ranking along a proxy metric (e.g. convex hull area). The strongest evidence we find is for use of a “centroid” proxy to estimate means in bar charts. Finally, we attempt to use using human-guided optimization to construct charts de novo, without assuming specific proxies. This work contributes both to perceptual psychology, by offering evidence for underlying visual processes that may be involved in the interpretation of comparative visualizations, and to data visualization, by providing new research methods and straightforward design guidance on how best to lay out charts to support certain tasks.Item DESIGNING AND IMPLEMENTING ACCESSIBLE WEARABLE INTERACTIONS FOR PEOPLE WITH MOTOR IMPAIRMENTS(2018) Malu, Meethu; Findlater, Leah; Computer Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Emerging wearable technologies like fitness bands, smartwatches, and head-mounted displays (HMDs) are entering the mainstream market. Unlike smartphones and tablets, these wearables, worn on the body or clothing, are always available and have the potential to provide quick access to information [7]. For instance, HMDs can provide relatively hands-free interaction compared to smartphones, and smartwatches and activity trackers can collect continuous health and fitness-related information of their wearer. However, there are over 20 million people in the U.S. with upper body motor impairments [133], who may not be able to gain from the potential benefits of these wearables. For example, the small interaction spaces of smartwatches may present accessibility challenges. Yet, few studies have explored the potential impacts or evaluated the accessibility of these wearables or investigated ways to design accessible wearable interactions for people with motor impairments. To inform the design of future wearable technologies, my dissertation investigates three threads of research: (1) assessing the accessibility of wearable technologies like HMDs, smartwatches and fitness trackers; (2) understanding the potential impacts of sharing automatically tracked fitness-related information for people with mobility impairments; and (3) implementing and evaluating accessible interactions for HMDs and smartwatches. As part of my first research thread, I conducted two formative studies investigating the accessibility of HMDs and fitness trackers and found that people with motor impairments experienced accessibility challenges like problematic form factors, irrelevant data tracking and difficulty with existing input. For my second research thread, I investigated the potential impacts of sharing automatically tracked data from fitness trackers with peers with similar impairments and therapists and presented design opportunities to build tools to support sharing. Towards my third research thread, I addressed the earlier issues identified with HMD accessibility by building custom wearable touchpads to control a commercial HMD. Next, I explored the touchscreen and non-touchscreen areas (bezel, wristband and user’s body) of smartwatches for accessible interaction. And, lastly, I built and compared bezel input with touchscreen input for accessible smartwatch interaction. The techniques implemented and evaluated in this dissertation will enable more equitable and independent use of wearable technologies for people with motor impairments.Item The Cost of Turning Heads - The Design and Evaluation of Vocabulary Prompts on a Head-Worn Display to Support Persons with Aphasia in Conversation(2015) Williams, Kristin; Findlater, Leah; Geography/Library & Information Systems; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Symbol-based dictionaries could provide persons with aphasia a resource for finding needed words, but they can detract from conversation. This research explores the potential of head-worn displays (HWDs) to provide glanceable vocabulary support that is unobtrusive and always-available. Two formative studies explored the benefits and challenges of using a HWD, and evaluated a proof-of-concept prototype in both lab and field settings. These studies showed that a HWD may allow wearers to maintain focus on the conversation, reduce reliance on external support (e.g., paper and pen, or people), and minimize the visibility of support by others. A third study compared use of a HWD to a smartphone, and found preliminary evidence that the HWD may offer a better overall experience with assistive vocabulary and may better support the wearer in advancing through conversation. These studies should motivate further investigation of head-worn conversational support.Item Pixel: A Tool for Creative Design with Physical Materials and Computation(2015) Gubbels, Michael; Froehlich, Jon E; History/Library & Information Systems; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Creating information systems that sense and respond to the physical environment is a complex activity, requiring technical skills from disparate areas of practice, such as computer programming and electronic circuitry. Although recent tools have lowered barriers to creating such systems, they tend to be too technical and constraining for creating systems to be a feasible everyday activity. These tools often rely on traditional interaction techniques and draw makers’ attention away from the system being built, thereby limiting makers’ physical movement, removing systems from their use context, and preventing contextualized experimentation with system designs. This thesis explores techniques for designing tools with support for making systems a more feasible everyday activity. I present the novel design and evaluation of such a tool called Pixel designed to let makers use intuitive knowledge derived from experience with the physical world, rather than technical expertise, in creating custom information systems in the course of everyday life.Item Crowdsourcing decision support: frugal human computation for efficient decision input acquisition(2014) Quinn, Alexander James; Bederson, Benjamin B; Computer Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)When faced with data-intensive decision problems, individuals, businesses, and governmental decision-makers must balance trade-offs between optimality and the high cost of conducting a thorough decision process. The unprecedented availability of information online has created opportunities to make well-informed, near-optimal decisions more efficiently. A key challenge that remains is the difficulty of efficiently gathering the requisite details in a form suitable for making the decision. Human computation and social media have opened new avenues for gathering relevant information or opinions in support of a decision-making process. It is now possible to coordinate paid web workers from online labor markets such as Amazon Mechanical Turk and others in a distributed search party for the needed information. However, the strategies that individuals employ when confronted with too much information--satisficing, information foraging, etc.--are more difficult to apply with a large, distributed group. Consequently, current distributed approaches are inherently wasteful of human time and effort. This dissertation offers a method for coordinating workers to efficiently enter the inputs for spreadsheet decision models. As a basis for developing and understanding the idea, I developed AskSheet, a system that uses decision models represented as spreadsheets. The user provides a spreadsheet model of a decision, the formulas of which are analyzed to calculate the value of information for each of the decision inputs. With that, it is able to prioritize the inputs and make the decision input acquisition process more frugal. In doing so, it trades machine capacity for analyzing the model for a reduction in the cost and burden to the humans providing the needed information.Item ACCESSIBILITY IN CONTEXT: UNDERSTANDING THE TRULY MOBILE EXPERIENCE OF USERS WITH MOTOR IMPAIRMENTS(2014) Naftali, Maia; Findlater, Leah; History/Library & Information Systems; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Touchscreen smartphones are becoming broadly adopted by the US population. Ensuring that these devices are accessible for people with disabilities is critical for equal access. For people with motor impairments, the vast majority of studies on touchscreen mobile accessibility have taken place in the laboratory. These studies show that while touchscreen input offers advantages, such as requiring less strength than physical buttons, it also presents accessibility challenges, such as the difficulty of tapping on small targets or making multitouch gestures. However, because of the focus on controlled lab settings, past work does not provide an understanding of contextual factors that impact smartphone use in everyday life, and the activities these devices enable for people with motor impairments. To investigate these issues, this thesis research includes two studies, first, an in-person study with four participants with motor impairments that included diary entries and an observational session, and, secondarily, an online survey with nine respondents. Using case study analysis for the in-person participants, we found that mobile devices have the potential to help motor-impaired users reduce the physical effort required for everyday tasks (e.g., turning on a TV, checking transit accessibility in advance), that challenges in touchscreen input still exist, and that the impact of situational impairments to this population can be impeding. The online survey results confirm these findings, for example, highlighting the difficulty of text input, particularly when users are out and mobile rather than at home. Based on these findings, future research should focus on the enhancement of current touchscreen input, exploring the potential of wearable devices for mobile accessibility, and designing more applications and services to improve access to physical world.Item COMPARING SMALL GRAPHS: HOW DISTANCE, ORIENTATION, AND ALIGNMENT AFFECT THE COMPARABILITY OF SMALL MULTIPLE BAR GRAPHS(2012) Smith, Benjamin Keniray; Norman, Kent L; Neuroscience and Cognitive Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Small multiples play a vital and growing role in the display of complex information. They are particularly useful for depicting spatiotemporal data, for which more traditional graphs and maps are inadequate. However, the scientific investigation of the usefulness of small multiples has been limited and often misdirected. In five experiments, small bar graphs are used to investigate several factors that could influence the comparability of the small graphs that comprise a small multiples graph. These factors include the distance between the graphs, the alignment of the graphs, the orientation of the bars, the length of the bars, and whether the graphs contain a single bar or multiple bars. In all cases, the most important factor affecting the comparability of the graphs was the difference in lengths, or difference in the increase of lengths, that the participants were asked to compare. The effects of distance were greater when the bars were closer to each other than when they were farther apart, suggesting that the bars are Title of Dissertation: COMPARING SMALL GRAPHS: HOW DISTANCE, ORIENTATION, AND ALIGNMENT AFFECT THE COMPARABILITY OF SMALL MULTIPLE BAR GRAPHS Benjamin Keniray Smith, Doctor of Philosophy, 2012 Dissertation Directed By: Professor Kent L. Norman, Department of Psychology compared using central vision. For pairs of graphs with a single bar each, comparability decreased as the distance between the graphs increased, although this effect was more prominent measured by accuracy than response time. Graph arrangements with horizontal alignments and vertical orientations were more comparable, although these effects were more subtle than the distance effects. For pairs of graphs with two bars each, the distance between the graphs had no effect on the accuracy of the comparison, and only a slight effect on the response time. Alignment and orientation had no effect on the comparability of graphs with two lines. The similarity of the lines in each graph, including but not limited to the critical length increase, significantly affected the comparability of the graphs. Part of a graph difficulty principle for small multiple graphs is offered as advice for graph creators.Item Web Navigation Strategy and Performance(2007-05-06) Campbell, Susan Grace; Norman, Kent L; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The task of web navigation, or finding information on the World Wide Web, appears to depend on spatial cognition and problem solving. Spatial visualization ability is commonly considered to determine efficiency of performance on web search and navigation tasks. In order to investigate the mechanism for this improved efficiency, we developed two conceptual models of the relationship between strategy choice and spatial visualization ability. We found mixed results in three experiments. Of the first two, one suggested that spatial visualization ability predicts performance on web navigation tasks, and one suggested that there was no relationship. In both of these experiments, we also found that web navigation task performance was heavily dependent on strategy. The third experiment showed a relationship between strategy choice and performance as well as between spatial visualization ability and performance, but it did not suggest that spatial visualization ability determines strategy choice.Item Supporting Exploratory Web Search With Meaningful and Stable Categorized Overviews(2006-04-28) Kules, Bill; Shneiderman, Ben; Computer Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This dissertation investigates the use of categorized overviews of web search results, based on meaningful and stable categories, to support exploratory search. When searching in digital libraries and on the Web, users are challenged by the lack of effective overviews. Adding categorized overviews to search results can provide substantial benefits when searchers need to explore, understand, and assess their results. When information needs are evolving or imprecise, categorized overviews can stimulate relevant ideas, provoke illuminating questions, and guide searchers to useful information they might not otherwise find. When searchers need to gather information from multiple perspectives or sources, categorized overviews can make those aspects visible for interactive filtering and exploration. However, they add visual complexity to the interface and increase the number of tactical decisions to be made while examining search results. Two formative studies (N=18 and N=12) investigated how searchers use categorized overviews in the domain of U.S. government web search. A third study (N=24) evaluated categorized overviews of general web search results based on thematic, geographic, and government categories. Participants conducted four exploratory searches during a two hour session to generate ideas for newspaper articles about specified topics. Results confirmed positive findings from the formative studies, showing that subjects explored deeper while feeling more organized and satisfied, but did not find objective differences in the outcomes of the search task. Results indicated that searchers use categorized overviews based on thematic, geographic, and organizational categories to guide the next steps in their searches. This dissertation identifies lightweight search actions and tactics made possible by adding a categorized overview to a list of web search results. It describes a design space for categorized overviews of search results, and presents a novel application of the brushing and linking technique to enrich search result interfaces with lightweight interactions. It proposes a set of principles, refined by the studies, for the design of exploratory search interfaces, including "Organize overviews around meaningful categories," "Clarify and visualize category structure," and "Tightly couple category labels to search result list." These contributions will be useful to web search researchers and designers, information architects and web developers.