The impact of encumbrance on mobile interactions

Part 1: Long and Short Papers (Continued); International audience; This paper investigates the effects of encumbrance (holding different types of objects while using mobile devices) to understand the interaction difficulties that it causes. An experiment was conducted where participants performed a target acquisition task on a touchscreen mobile phone while carrying different types of bags and boxes. Mobility was also evaluated since people carry items from one place to another. Motion capture hardware was used to track hand and arm postures to examine how holding the different types of objects caused excessive movement and instability therefore resulting in performance to decline. The results showed encumbrance and mobility caused target accuracy to decrease although input while holding the box under the non-dominant arm was more accurate and exerted quicker targeting times than holding no objects. Encumbrance affected the dominant hand more than the non-dominant hand as targeting error significantly increased and caused greater hand instability. The issues caused by encumbrance suggest the topic requires more attention from researchers and users would benefit greatly if better interaction techniques and applications are developed to counteract the problems. Document type: Part of book or chapter of boo

Doctor of Philosophy

dissertationOfficial policy narratives in the juvenile-justice system have historically vacillated between orientations to punish and rehabilitate. Yet research suggests that despite dramatic policy changes, the primary narrative of the juvenile-justice system is one of continuity. This dissertation examines how day-to-day interactions between youth and staff in a juvenile secure-care setting express public policy in ways that account for slippage between official articulations and their implemented versions. Using policy documents along with field research that includes ethnographic observations, indepth interviews, and case file reviews, this study both investigates the local setting as a site of politics and reaches across levels of analysis to offer recommendations for juvenile-justice policy implementation and service-delivery practice. It identifies insights into how policy and practice affect conceptions of identity at personal and collective levels. In secure care, interactions between youth and staff occur in an environment that is highly disparate in terms of power and yet is still one of mutual influence. Interactions have important consequences for policy, treatment services, and identity. They affect both youth-identity formation â€" a central part of the adolescent-development project â€" and staff professional identity. The quality of interactions in secure care can affect program outcomes, including youth openness to treatment, legal socialization, and recidivism. Further, I show staff behaviors and professional identities to be at risk due to the contagious influence of youth street mentalities. Key recommendations seek to enhance developmentally-appropriate and evidence-based efforts to treat delinquency, including: 1) the fostering of a productive pluralism in secure care; 2) the incorporation of procedural-justice approaches to improve the quality of interactions at multiple organizational levels; and 3) the import of a critical consonance between what we teach youth and how we teach them

Sensor-based user interface concepts for continuous, around-device and gestural interaction on mobile devices

A generally observable trend of the past 10 years is that the amount of sensors embedded in mobile devices such as smart phones and tablets is rising steadily. Arguably, the available sensors are mostly underutilized by existing mobile user interfaces. In this dissertation, we explore sensor-based user interface concepts for mobile devices with the goal of making better use of the available sensing capabilities on mobile devices as well as gaining insights on the types of sensor technologies that could be added to future mobile devices. We are particularly interested how novel sensor technologies could be used to implement novel and engaging mobile user interface concepts. We explore three particular areas of interest for research into sensor-based user interface concepts for mobile devices: continuous interaction, around-device interaction and motion gestures. For continuous interaction, we explore the use of dynamic state-space systems to implement user interfaces based on a constant sensor data stream. In particular, we examine zoom automation in tilt-based map scrolling interfaces. We show that although fully automatic zooming is desirable in certain situations, adding a manual override capability of the zoom level (Semi-Automatic Zooming) will increase the usability of such a system, as shown through a decrease in task completion times and improved user ratings of user study. The presented work on continuous interaction also highlights how the sensors embedded in current mobile devices can be used to support complex interaction tasks. We go on to introduce the concept of Around-Device Interaction (ADI). By extending the interactive area of the mobile device to its entire surface and the physical volume surrounding it we aim to show how the expressivity and possibilities of mobile input can be improved this way. We derive a design space for ADI and evaluate three prototypes in this context. HoverFlow is a prototype allowing coarse hand gesture recognition around a mobile device using only a simple set of sensors. PalmSpace a prototype exploring the use of depth cameras on mobile devices to track the user's hands in direct manipulation interfaces through spatial gestures. Lastly, the iPhone Sandwich is a prototype supporting dual-sided pressure-sensitive multi-touch interaction. Through the results of user studies, we show that ADI can lead to improved usability for mobile user interfaces. Furthermore, the work on ADI contributes suggestions for the types of sensors could be incorporated in future mobile devices to expand the input capabilities of those devices. In order to broaden the scope of uses for mobile accelerometer and gyroscope data, we conducted research on motion gesture recognition. With the aim of supporting practitioners and researchers in integrating motion gestures into their user interfaces at early development stages, we developed two motion gesture recognition algorithms, the $3 Gesture Recognizer and Protractor 3D that are easy to incorporate into existing projects, have good recognition rates and require a low amount of training data. To exemplify an application area for motion gestures, we present the results of a study on the feasibility and usability of gesture-based authentication. With the goal of making it easier to connect meaningful functionality with gesture-based input, we developed Mayhem, a graphical end-user programming tool for users without prior programming skills. Mayhem can be used to for rapid prototyping of mobile gestural user interfaces. The main contribution of this dissertation is the development of a number of novel user interface concepts for sensor-based interaction. They will help developers of mobile user interfaces make better use of the existing sensory capabilities of mobile devices. Furthermore, manufacturers of mobile device hardware obtain suggestions for the types of novel sensor technologies that are needed in order to expand the input capabilities of mobile devices. This allows the implementation of future mobile user interfaces with increased input capabilities, more expressiveness and improved usability

HandSight: A Touch-Based Wearable System to Increase Information Accessibility for People with Visual Impairments

Many activities of daily living such as getting dressed, preparing food, wayfinding, or shopping rely heavily on visual information, and the inability to access that information can negatively impact the quality of life for people with vision impairments. While numerous researchers have explored solutions for assisting with visual tasks that can be performed at a distance, such as identifying landmarks for navigation or recognizing people and objects, few have attempted to provide access to nearby visual information through touch. Touch is a highly attuned means of acquiring tactile and spatial information, especially for people with vision impairments. By supporting touch-based access to information, we may help users to better understand how a surface appears (e.g., document layout, clothing patterns), thereby improving the quality of life. To address this gap in research, this dissertation explores methods to augment a visually impaired user’s sense of touch with interactive, real-time computer vision to access information about the physical world. These explorations span three application areas: reading and exploring printed documents, controlling mobile devices, and identifying colors and visual textures. At the core of each application is a system called HandSight that uses wearable cameras and other sensors to detect touch events and identify surface content beneath the user’s finger. To create HandSight, we designed and implemented the physical hardware, developed signal processing and computer vision algorithms, and designed real-time feedback that enables users to interpret visual or digital content. We involve visually impaired users throughout the design and development process, conducting several user studies to assess usability and robustness and to improve our prototype designs. The contributions of this dissertation include: (i) developing and iteratively refining HandSight, a novel wearable system to assist visually impaired users in their daily lives; (ii) evaluating HandSight across a diverse set of tasks, and identifying tradeoffs of a finger-worn approach in terms of physical design, algorithmic complexity and robustness, and usability; and (iii) identifying broader design implications for future wearable systems and for the fields of accessibility, computer vision, augmented and virtual reality, and human-computer interaction

Social Connection in the City: Representations and Motivations

A longstanding sociological tradition conceives of city life as profoundly alienating and insular (Durkheim, 1897; Simmel, 1903). As UK cities continue to grow this could be detrimental for city dwellers as a vast amount of evidence underpins the notion that connecting with others is crucial for wellbeing (Aked, 2011). Although the link between social connectedness and wellbeing is well established, less is known about how connecting with different types of social ties is represented by lay people and what motivates this desire to connect. Using Social Representations Theory and Mattering theory, the aim is to examine the content and the underlying structure that shapes common-sense thinking about social connectedness in the contemporary British city and understand the social psychological complexities that shape motivations for connecting with others. To do this, three studies were conducted using the Grid Elaboration Method (GEM) (Joffe and Elsey, 2014), a novel free association and interview technique. All studies were conducted in Britain’s two largest cities, London and Birmingham. In Study 1, city-dwellers’ aspirations were examined to look at the importance of social connectedness compared to other aspirations. Thematic analysis of 96 interviews revealed that social connectedness is the most prevalent aspiration and includes connection with ‘strong ties’, such as friends and family, and ‘weak ties’, such as strangers and acquaintances at work, in the community and the city at-large. In Study 2 and Study 3, a deeper exploration of connectedness with friends and weak ties was conducted. Building on the first study, thematic analysis of the interviews from 52 city dwellers revealed that thinking about social connection is shaped by the ‘self/other’ thema, is motivated by a desire to ‘matter’ and shaped by city contextual factors such as time and technology. This work makes a unique contribution to the study of social connectedness in the city and could be applied to create more effective wellbeing interventions and policies