Proximate mobile devices that are aware of their orientation relative to one another can support novel and natural forms of interaction. In this paper, we present a method to determine the relative orientation of proximate mobile devices using only the backside camera. We implemented this method as a service called Orienteer, which provides mobile device with the orientation of other proximate mobile devices. We demonstrate that orientation information can be used to enable novel and natural interactions by developing two applications that allow the user to push content in the direction of another device to share it and point the device toward another to filter content based on the device's owner. An informal evaluation revealed that interactions built upon orientation information can be natural and compelling to users, but developers and designers need to carefully consider how orientation should be applied effectively.

An essential aspect of learning a second language is the acquisition of vocabulary. However, acquiring vocabulary is often a protracted process that requires repeated and spaced exposure; which can be difficult to accommodate given the busyness of daily living. In this paper, we explore if a learner can implicitly acquire second language vocabulary through her explicit interactions with her mobile phone (e.g., navigating multiple home screens) using an interface we developed called Vocabulary Wallpaper. In addition, we examine if the type of vocabulary this technique exposes to the learner, whether it is contextually relevant or contextually-independent will influence the learner's rate of vocabulary acquisition. The results of our study show participants were able to use Vocabulary Wallpaper to increase the number of second language vocabulary that they can recognize and recall and their rate of vocabulary acquisition was significantly greater when presented with a contextually relevant vocabulary than a contextually-independent vocabulary.

People often complete tasks and to-dos not only for themselves but also for others in their household. In this work, we examine how household members share and accomplish errands both individually and together. We conducted a three-week diary study with eight households to understand the types of errands that family members and roommates share with each other. We explore their motivations for offering and requesting help to complete their errands and the variety of methods for doing so. Our findings reveal when participants sometimes face challenges completing their errands, and how household members request and receive help. We learned that the cooperative performance of errands is typically dependent on household members' location, availability, and capability. Using these findings, we discuss design opportunities for cooperative errands sharing systems that can assist households.

A rich cognitive map of a space can enhance the individual's experience within the space. However, cognitive maps develop gradually through repeated experience; and because of this, on-demand mobile search services (e.g., Google Maps, Yelp) are often used to compensate for missing knowledge. In this work, we developed and evaluated a context-aware place discovery application called Opportunities Exist to assist in the acquisition of spatial knowledge and meaning. The application differs from traditional search in that places are discovered using an activity (e.g., drink coffee, sit in the sun) and the discovery process runs continuously, maintaining a history of places the user can perform her activities as she goes about her day. We conducted a 4-week deployment in two North American cities. The results show that users were able to discover new places to perform their activities in familiar spaces and learned to associate new activities with familiar places. In addition, participants leveraged the application to perform activities opportunistically, and used continuous place discovery as an opportunistic reminder of routines they wanted to break out of or resume.

Accessing the advanced functions of a mobile phone is not a trivial task for users with visual impairments. They rely on screen readers and voice commands to discover and execute functions. In mobile situations, however, screen readers are not ideal because users may depend on their hearing for safety, and voice commands are difficult for a system to recognize in noisy environments. In this paper, we extend Virtual Shelves--an interaction technique that leverages proprioception to access application shortcuts--for visually impaired users. We measured the directional accuracy of visually impaired participants and found that they were less accurate than people with vision. We then built a functional prototype that uses an accelerometer and a gyroscope to sense its position and orientation. Finally, we evaluated the interaction and prototype by allowing participants to customize the placement of seven shortcuts within 15 regions. Participants were able to access shortcuts in their personal layout with 88.3% accuracy in an average of 1.74 seconds.

Posing a question to an online question and answer community does not guarantee a response. Significant prior work has explored and identified members' motivations for contributing to communities of collective action (e.g., Yahoo! Answers); in contrast it is not well understood why members choose to not answer a question they have already read. To explore this issue, we surveyed 135 active members of Yahoo! Answers. We show that top and regular contributors experience the same reasons to not answer a question: subject nature and composition of the question; perception of how the questioner will receive, interpret and react to their response; and a belief that their response will lose its meaning and get lost in the crowd if too many responses have already been given. Informed by our results, we discuss opportunities to improve the efficacy of the question and answer process, and to encourage greater contributions through improved design.

Community-authored content, such as location specific reviews, offers a wealth of information about virtually every imaginable location today. In this work, we process Yelp's community-authored reviews to identify a set of potential activities that are supported by the location reviewed. Using 14 test locations we show that the majority of the 40 most common results per location (determined by verb-noun pair frequency) are actual activities supported by their respective locations, achieving a mean precision of up to 79.3%. Although the number of reviews authored for a location has a strong influence on precision, we are able to achieve a precision up to 29.5% when processing only the first 50 reviews, increasing to 45.7% and 57.3% for the first 100 and 200 reviews, respectively. In addition, we present two context-aware services that leverage location-based activity information on a city scale that is accessible through a Web service we developed supporting multiple cities in North America.

Home networks are common but notoriously difficult to setup and maintain. The difficulty users experience in setting up and maintaining their home network is problematic because of the numerous security threats that can exploit poorly configured and maintained network security. Because there is little empirical data to characterize the usability problems associated with the adoption of wireless network security, we surveyed primary caretakers and users of 20 home networks, examining their perceptions and usage of the security features available to them. We found that users did not understand the difference between access control lists and encryption, and that devices fail to properly notify users of weak security configuration choices. To address these issues, we designed and evaluated a novel wireless router configuration wizard that encouraged strong security choices by improving the network configuration steps. We found that security choices made by users of our wizard resulted in stronger security practices when compared to the wizard from a leading equipment manufacturer.

Visually demanding interfaces on a mobile phone can diminish the user experience by monopolizing the user's attention when they are focusing on another task and impede accessibility for visually impaired users. Because mobile devices are often located in pockets when users are mobile, explicit foot movements can be defined as eyes-and-hands-free input gestures for interacting with the device. In this work, we study the human capability associated with performing foot-based interactions which involve lifting and rotation of the foot when pivoting on the toe and heel. Building upon these results, we then developed a system to learn and recognize foot gestures using a single commodity mobile phone placed in the user's pocket or in a holster on their hip. Our system uses acceleration data recorded by a built-in accelerometer on the mobile device and a machine learning approach to recognizing gestures. Through a lab study, we demonstrate that our system can classify ten different foot gestures at approximately 86% accuracy.

Large information displays are common in public and semi-public spaces but still require rapid and lightweight ways for users to interact with them. We present BlueTone, a framework for developing large display applications which will interpret and react to dual-tone multi-frequency sounds transmitted from mobile phones paired with the display using the Bluetooth headset profile. BlueTone enables text entry, cursor manipulation and menu selection without requiring the installation of any special software on a user's mobile phone.

Triggering shortcuts or actions on a mobile device often requires a long sequence of key presses. Because the functions of buttons are highly dependent on the current application's context, users are required to look at the display during interaction, even in many mobile situations when eyes-free interactions may be preferable. We present Virtual Shelves, a technique to trigger programmable shortcuts that leverages the user's spatial awareness and kinesthetic memory. With Virtual Shelves, the user triggers shortcuts by orienting a spatially-aware mobile device within the circular hemisphere in front of her. This space is segmented into definable and selectable regions along the phi and theta planes. We show that users can accurately point to 7 regions on the theta and 4 regions on the phi plane using only their kinesthetic memory. Building upon these results, we then evaluate a proof-of-concept prototype of the Virtual Shelves using a Nokia N93. The results show that Virtual Shelves is faster than the N93's native interface for common mobile phone tasks.

The number of computing devices that people use is growing. To gain a better understanding of why and how people use multiple devices, we interviewed 27 people from academia and industry. From these interviews we distill four primary findings. First, associating a user's activities with a particular device is problematic for multiple device users because many activities span multiple devices. Second, device use varies by user and circumstance; users assign different roles to devices both by choice and by constraint. Third, users in industry want to separate work and personal activities across work and personal devices, but they have difficulty doing so in practice Finally, users employ a variety of techniques for accessing information across devices, but there is room for improvement: participants reported managing information across their devices as the most challenging aspect of using multiple devices. We suggest opportunities to improve the user experience by focusing on the user rather than the applications and devices; making devices aware of their roles; and providing lighter-weight methods for transferring information, including synchronization services that engender more trust from users.

A person often has highly context-sensitive information needs that require assistance from individuals in their social network. However, a person's social network is often not broad enough to include the right people in the right situations or circumstances who can satisfy the needs. The ability to satisfy context-sensitive information needs depends on a person's ability to seek the answers from appropriate individuals, who must then provide a response in a timely manner. To gain an understanding of how to better support the sharing of information, we conducted a four-week diary study examining 20 people's perceived daily information needs and sharing desires. We provide a structured framework for understanding the types of information people need and discuss when and how people are able to satisfy their needs. Using these findings, we discuss research and design opportunities for addressing the shortcomings of the existing information sources by connecting information altruists with an audience by leveraging weak ties through situation and circumstance, and providing a timely asynchronous connection to these sources.

In this paper, we explore the use of an interaction technique called sequential segmentation to support target selection for mobile devices. Sequential segmentation iteratively partitions an information space into selectable regions and subsequent sub-regions where each region/sub-region is labeled (1--9) and is mapped to the corresponding key on the mobile device's numeric keypad. We conducted a study comparing the sequential technique to the directional pad for target selection. The results show that the directional pad is significantly faster than sequential for selecting targets that require three or less interactions with the directional pad. However, sequential is significantly faster than the directional pad for targets that require five or more interactions with the directional pad. User feedback shows a preference for sequential and that it is perceived easier to use than the directional pad.

The effectiveness of interaction with mobile devices can be impacted by handedness; however, support for handedness in the interface is rarely provided. The goal of this article is to demonstrate that handedness is a significant interface consideration that should not be overlooked. Four studies were conducted to explore left‐handed user interaction with right‐ or left‐aligned scrollbars on personal digital assistants. Analysis of the data shows that left‐handed users are able to select targets significantly faster using a left‐aligned scrollbar when compared to a right‐aligned scrollbar. User feedback also indicated that a left‐aligned scrollbar was preferred by left‐handed users and provided more natural interaction.

In this paper, we present a field study comparing software-based navigation techniques (scrollbars, tap-and-drag, and touch-n-go) on mobile devices. In particular, we were interested in exploring the efficiency and user preference of these navigation techniques for different levels of mobility (sitting, walking, and standing) in a naturalistic environment. Results show that while there was no significant difference in performance between tap-and-drag and touch-n-go, both techniques significantly outperformed scrollbars for simple, multi-directional navigation tasks. In addition, the users preferred the touch-n-go technique over the other two methods. The results also revealed that users' interactions and preferences differed between the levels of mobility.

Emerging technologies such as location-awareness devices have the potential to significantly impact users’ social coordination, particularly while rendezvousing. It is important that we explore how new technologies influence social behaviours and communication in order to realize their full potential. This paper presents a field study investigating the use of mobile location-aware devices for rendezvous activities. Participants took part in one of three mobile device conditions (a mobile phone, a location-aware handheld, or both a mobile phone and a location-aware handheld) and completed three rendezvousing scenarios. The results reveal key differences in communication patterns between the mediums, as well as the potential strengths and limitations of location-aware devices for social coordination. The paper concludes with a discussion of relevant design issues drawn from observations gathered during the field study.