Outdoor recreation improves quality of life for individuals with tetraplegia, however providing safe opportunities to engage in these sports has many challenges. We describe the iterative design and field evaluation of Tetra-Ski, a novel power-assisted ski chair. Users control Tetra-Ski with a joystick or Sip-and-Puff controller either independently or collaboratively with a tethered skier through our novel shared-control scheme. We also developed a training simulator to help prepare users prior to their skiing experience. A field study with eight participants and interviews with three trainers who used Tetra-Ski showed that Tetra-Ski is usable, enjoyable, and that the experience has a positive psychosocial effect on users. Furthermore, the shared-control scheme developed for Tetra-Ski proved crucial for supporting the unique abilities of different users, suggesting that a shared-control approach could enable broader access to less-dependent forms of outdoor recreation in the future.

Wireless implantable medical devices (IMDs) are cyber-physical systems that deliver life-saving treatments to cardiac patients with dangerous heart conditions. Current access control models for these systems are insufficient; more security is necessary. In response to this problem, the technical security community has investigated new directions for improving security on these resource-constrained devices. Defenses, however, must not only be technically secure; in order to be deployable, defenses must be designed to work within the needs and constraints of their relevant application spaces. Designing for an application space---particularly a specialized one---requires a deep understanding of the stakeholders, their values, and the contexts of technology usage. Grounding our work in value sensitive design (VSD), we collaborated as an interdisciplinary team to conduct three workshops with medical providers for the purpose of gathering their values and perspectives. The structure of our workshop builds on known workshop structures within the human-computer interaction (HCI) community, and the number of participants in our workshops (N=24) is compatible with current practices for inductive, exploratory studies. We present results on: what the participants find important with respect to providing care and performing their jobs; their reactions to potential security system concepts; and their views on what security system properties should be sought or avoided due to side effects within the context of their work practice. We synthesize these results, use the results to articulate design considerations for future technical security systems, and suggest directions for further research. Our research not only provides a contribution to security research for an important class of cyber-physical systems (IMDs); it also provides an example of leveraging techniques from other communities to better explore the landscape of security designs for technologies.

Augmented reality (AR) devices are poised to enter the market. It is unclear how the properties of these devices will affect individuals' privacy. In this study, we investigate the privacy perspectives of individuals when they are bystanders around AR devices. We conducted 12 field sessions in cafés and interviewed 31 bystanders regarding their reactions to a co-located AR device. Participants were predominantly split between having indifferent and negative reactions to the device. Participants who expressed that AR devices change the bystander experience attributed this difference to subtleness, ease of recording, and the technology's lack of prevalence. Additionally, participants surfaced a variety of factors that make recording more or less acceptable, including what they are doing when the recording is being taken. Participants expressed interest in being asked permission before being recorded and in recording-blocking devices. We use the interview results to guide an exploration of design directions for privacy-mediating technologies.

We scoped, designed, produced, and evaluated the effectiveness of a recreational tabletop card game created to raise awareness of and alter perceptions regarding-computer security. We discuss our process, the challenges that arose, and the decisions we made to address those challenges. As of May 2013, we have shipped approximately 800 free copies to 150 educators. We analyze and report on feedback from 22 of these educators about their experiences using Control-Alt-Hack with over 450 students in classroom and non-classroom contexts. The responses from the 14 educators who reported on their use of the game in a classroom context variously indicated that: their students' awareness of computer security as a complex and interesting field was increased (11/14); they would use the game again in their classroom (10/14); and they would recommend the game to others (13/14). Of note, 2 of the 14 classroom educators reported that they would not have otherwise covered the material. Additionally, we present results from user studies with 11 individuals and find that their responses indicate that 8 of the 11 had an increased awareness of computer security or a changed perception; furthermore, all of our intended goals are touched upon in their responses.

In this poster, we present Control-Alt-Hack": White Hat Hacking for Fun and Profit--a card game for computer security outreach and education. A general lack of awareness about computer security contributes to the insecurity of new consumer technologies. We seek to increase people's prioritization of computer security and their understanding of the variety of attacks and technologies that can be vulnerable to compromise. We work towards this goal via a recreational tabletop card game where people play as white hat hackers, using their characters' skills to perform a variety of hacking Missions. We licensed a game mechanic from a hobbyist game company, worked with graphic designers and illustrators, and rewrote card text to make the game about working as a computer security professional. Visit www.controlalthack.com for supplementary educational materials and to request free educator copies.

Knowledge-based authentication systems generally rely upon users' explicit recollection of passwords, facts, or personal preferences. These systems impose a cognitive burden that often results in forgotten secrets or secrets with poor entropy. We propose an authentication system that instead draws on implicit memory - that is, the unconscious encoding and usage of information. In such a system, a user is initially presented with images of common objects in a casual familiarization task. When the user later authenticates, she is asked to perform a task involving a set of degraded images, some of which are based upon the images in the familiarization task. The prior exposure to those images influences the user's responses in the task, thereby eliciting authentication information. We ran a user study to investigate the plausibility of our system design. Our results suggest that implicit memory has potential as a basis for low-cognitive-overhead, high-stability, knowledge-based authentication.

Implantable medical devices (IMDs) improve patients' quality of life and help sustain their lives. In this study, we explore patient views and values regarding their devices to inform the design of computer security for wireless IMDs. We interviewed 13 individuals with implanted cardiac devices. Key questions concerned the evaluation of 8 mockups of IMD security systems. Our results suggest that some systems that are technically viable are nonetheless undesirable to patients. Patients called out a number of values that affected their attitudes towards the systems, including perceived security, safety, freedom from unwanted cultural and historical associations, and self-image. In our analysis, we extend the Value Sensitive Design value dams and flows technique in order to suggest multiple, complementary systems; in our discussion, we highlight some of the usability, regulatory, and economic complexities that arise from offering multiple options. We conclude by offering design guidelines for future security systems for IMDs.

Future homes will be populated with large numbers of robots with diverse functionalities, ranging from chore robots to elder care robots to entertainment robots. While household robots will offer numerous benefits, they also have the potential to introduce new security and privacy vulnerabilities into the home. Our research consists of three parts. First, to serve as a foundation for our study, we experimentally analyze three of today's household robots for security and privacy vulnerabilities: the WowWee Rovio, the Erector Spykee, and the WowWee RoboSapien V2. Second, we synthesize the results of our experimental analyses and identify key lessons and challenges for securing future household robots. Finally, we use our experiments and lessons learned to construct a set of design questions aimed at facilitating the future development of household robots that are secure and preserve their users' privacy.

Peer review is widely recognized for advancing student learning, in particular for developing reflective processes like critical thinking. The classroom is ripe for peer review because the subject matter is fresh and in-depth interactivity is possible. Yet the limited time available in class conflicts with peer review's deliberative nature. We hypothesize that peer review -- at least the initial stages of it -- can be supported in the classroom with tools for facilitating the rapid identification of interesting issues for discussion. The potential benefits of such a tool include: furthering the student-focus of in-class active learning activities, further implanting critical analysis skills through frequent in-class use, supporting immediate feedback, and enabling comparison of student and instructor-modeled critical analysis.This paper explores tool support for in-class lightweight preliminary peer-review (LPPR): peer review that is instigated in the classroom, but does not necessarily end there. We proposed that students classify peer solutions in 4 dimensions: correctness, comprehension (e.g., "do I understand this solution"), worthiness for discussion, and similarity to the evaluator's own solution. We designed an LPPR extension to Ubiquitous Presenter, and then conducted an exploratory study in a mock classroom setting. We found that LPPR can quickly identify a subset of student solutions that warrant immediate discussion, and that modest amounts of reflection arise from the LPPR process.

Research has shown that educational technology can broaden and enhance the use of active learning in large classrooms. An educational technology platform often relies on students to bring laptops or specialized wireless devices like clickers to interact through the system. Mobile phones are an attractive alternative, as most students already possess them, they have more capabilities than dedicated clickers, and yet are small enough to minimize interference with note taking on a classroom desk.This paper presents the design and use of a mobile phone extension to Ubiquitous Presenter, which allows students to submit solutions to active learning exercises in the form of text or photo messages. In an exploratory study, students found that text messaging worked well for exercises with multiple choice or short answers. Entering symbols common to computer science was difficult. Many problems were more suitable to photo messaging of a handwritten answer, although image quality must be managed. The phone's small size left space for the use of a notebook. The students had concerns about the message charges that would accrue in use. In conclusion, we offer recommendations to instructors and system designers interested in leveraging mobile phones to increase communication in the classroom.

Experimentation has shown that in-class educational technologies, by permitting anonymous, authored participation, can dramatically alter student communications in the classroom. Now, the appearance of dual pen-and-keyboard computing devices in the university classroom, notably Tablet PCs, motivates thinking critically about how different expressive modalities could improve in-class student problem -solving and communication.This paper describes the use of Ubiquitous Presenter 2.0 in a study to discover the driving issues of multimodality for both in-class technologies and student exercises. This paper sensitizes instructors to the issues of modality and makes specific recommendations for application design. We find that the choice of modality is not merely one of efficiency or naturalness, but is loaded with numerous personal, social, and material considerations. Although use of the pen (over typed text) is generally preferred, we find that choice itself is critical to encouraging student creativity, collaboration, and communication.