People use social-photography services to tell stories about themselves and to solicit responses from viewers. State of the-art services concentrate on textual comments, "Like" buttons, or similar means for viewers to give explicit feedback, but they overlook other, non-textual means. This paper investigates how emotion responses--as video clips captured by the front camera of a cell phone and used as tags for the individual photo viewed--can enhance photo-sharing experiences for close-knit groups. Our exploration was carried out with a mobile social-photography service called Social Camera. Four user groups (N=19) used the application for two to four weeks. The study's results support the value of using front-camera video recordings to glean emotion response. It supports lightweight phatic social interactions not possible with comments and "Like" buttons. Most users kept sharing emotion responses throughout the study. They typically shared the responses right after they saw a just taken photo received from a remote partner. They used the responses to share their current contexts with others just as much as to convey nuanced feelings about a photo. We discuss the implications for future design and research.

Accessing social networking services is one key user activity on mobile devices. To characterize this experience, we conduct a user study with active users of mobile social networking services in South Korea. In the study, we interviewed 12 users and asked them to keep a diary for a week. The study shows awareness, social connection, and diversion as the key motivations for mobile access to social networking services. The users seldom resort to these services to fulfill curiosity about arbitrary questions or to seek information for productivity purposes, which they do with other mobile Internet services. The study reveals cross-medium alerts as a common trigger for mobile social networking sessions. We discuss implications of this user study for future work to promote mobile access to social networking services.

Mobile social network aggregators, such as Motoblur and Windows Phone 7 People Hub, emerge as a common tool to access online social networking services on mobile devices. There are limited user studies, however, about how people use and perceive these aggregators. In this study, I explore this research field by deploying an innovative mobile social network aggregator named Linked Internet UI, or LinkedUI. It deeply integrates social networking services into the mobile device user interface and recommends new content that is likely to be interesting to the user. The main research question is that of how people use and perceive these designs, and what user practices these designs enable. The supporting research emphasis is on exploring how we apply user-centered design in the era of online social networking services.

Some mobile devices automatically fetch content from social networking services and integrate it into the device user interface. In this paper, we explore how people consume integrated social networking services in a field study with an innovative aggregator named Linked Internet UI Concept, or LinkedUI. Twenty users completed the field study. We logged their activities and performed user interviews. The study reveals two main use cases: habitual checking where users frequently glanced at the integrated services at short intervals; and serendipitous content discovery where they come across some content when performing other tasks. The study also reveals that the users only attended to a small proportion of the full content set, such as content recently published and content from selected contacts. This indicates the user need of quick access to relevant content.

This article explores how people perceive interactive activities in order to inform navigation history design on mobile devices. Following event segmentation method, 12 participants were asked to break 6 episodes of mobile interaction into segments, organize the segments, and identify those deemed representative. Three findings emerged. First, when making sense of mobile interaction, users concentrate on the content objects on which actions are performed. This indicates the value of content-centric designs in navigation history and other mobile user interface designs. The content objects are data objects and their collections meaningful to the person dealing with it, for example, photos, messages, or albums. Second, users tend to employ two-level hierarchies in grouping segments, and use the similarity in content objects and applications as a reference. They deem the segments as representative where objects are created or changed, or where sharing or querying acts take place. These findings indicate how a navigation history design should organize and prioritize mobile interaction events. Finally, event perception shows relatively low interparticipant consensus, which indicates that navigation history designs have to accommodate large individual differences.

This paper presents the Linked Internet UI Concept, or LinkedUI for short, as a holistic user interface concept to facilitate social interaction on mobile devices. It aggregates social events from social networking services and communication channels and uses hypertext navigation for presentation and interaction. We describe the concept design principles, highlights of the design, and the prototype implementation. We conducted a user study to compare LinkedUI with the benchmark of web applications running in a web browser to follow their friends' activities in Twitter and Flickr and two other optional services on mobile devices. The study results reveal that the users performed tasks faster in LinkedUI and also liked it more than the benchmark. These findings support the design principles of LinkedUI in facilitating social interaction via mobile devices.

This paper describes a series of user studies on how people use the Web via mobile devices. The data primarily comes from contextual inquiries with 47 participants between 2004 and 2007, and is complemented with a phone log analysis of 577 panelists in 2007. We report four key contextual factors in using the Web on mobile devices and propose mobile Web activity taxonomy. The framework contains three user activity categories identical to previous stationary Web studies: information seeking, communication, and transaction, and a new category: personal space extension. The new category refers to the practice that people put their content on the Web for personal access, therefore extending their personal information space.

Handwriting recognition (HWR) input method has been considered to be one of the most usable text entry methods for handheld devices, especially for languages with large and complicated character sets such as Chinese. The paper studies stroke break times within handwritten characters and presents a new method for setting HWR timeout by examining the break time distributions. For multi-stroke character HWR input, a timeout is widely used as a segmentation technique to initiate the recognition process. In this paper, we examine the largest stroke break time in each character and explore the relationship between break time distribution and optimal HWR timeout. The study used Chinese as test material and the test independent variables were writing condition (input box, full screen) and user's posture while they were writing (hold device in hand, keep device on table). The main findings are: (1) the stroke break times are similar in full screen and input box conditions, though the users tend to write larger characters in full screen condition. (2) The stroke break times fit into a tight distribution. It is feasible to estimate optimal HWR timeout by studying stoke break time distribution. A nonparametric histogram method was used to model the stroke break distributions and it showed that typical Chinese HWR default timeouts are around 99% percentile in the distribution. (3) Differences in HWR stroke break distributions are very significant between individual users. The stroke break time analysis can also be applied to design HWR timeout customization scale.