Xiaojun Bi

Comparing usage of a large high-resolution display to single or dual desktop displays for daily work

With the ever increasing amount of digital information, users desire more screen real estate to process their daily computing work, and might well benefit from using a wall-size large high-resolution display instead of a desktop one. Unfortunately, we know very little about users behaviors when using such a display for daily computing. We present a week-long study that investigates large display use in a personal desktop computing context by comparing it with single and dual desktop monitor use. Results show users unanimous preference for using a large display: it facilitates multi-window and rich information tasks, enhances users awareness of peripheral applications, and offers a moreimmersive experience. Further, the data reveals distinct usage patterns in partitioning screen real estate and managing windows on a large display. Detailed analysis of these results provides insights into designing interaction techniques and window management systems more suited to a large display.

An exploration of pen rolling for pen-based interaction

Current pen input mainly utilizes the position of the pen tip, and occasionally, a button press. Other possible device parameters, such as rolling the pen around its longitudinal axis, are rarely used. We explore pen rolling as a supporting input modality for pen-based interaction. Through two studies, we are able to determine 1) the parameters that separate intentional pen rolling for the purpose of interaction from incidental pen rolling caused by regular writing and drawing, and 2) the parameter range within which accurate and timely intentional pen rolling interactions can occur. Building on our experimental results, we present an exploration of the design space of rolling-based interaction techniques, which showcase three scenarios where pen rolling interactions can be useful: enhanced stimulus-response compatibility in rotation tasks [7], multi-parameter input, and simplified mode selection.

Quasi-qwerty soft keyboard optimization

It has been well understood that optimized soft keyboard layouts improve motor movement efficiency over the standard Qwerty layouts, but have the drawback of long initial visual search time for novice users. To ease the initial searching time on optimized soft keyboards, we explored Quasi-Qwerty optimization so that the resulting layouts are close to Qwerty. Our results show that a middle ground between the optimized but new, and the familiar (Qwerty) but inefficient does exist. We show that by allowing letters to move at most one step (key) away from their original positions on Qwerty in an optimization process, one can achieve about half of what free optimization could gain in movement efficiency. An experiment shows that due to users familiarity with Qwerty, a layout with quasi Qwerty optimization could significantly reduce novice users visual search time to a level between those of Qwerty and a freely optimized layout. The results in this work provide designers with a new quantitative understanding of the soft keyboard design space.

Magic desk: bringing multi-touch surfaces into desktop work

Despite the prominence of multi-touch technologies, there has been little work investigating its integration into the desktop environment. Bringing multi-touch into desktop computing would give users an additional input channel to leverage, enriching the current interaction paradigm dominated by a mouse and keyboard. We provide two main contributions in this domain. First, we describe the results from a study we performed, which systematically evaluates the various potential regions within the traditional desktop configuration that could become multi-touch enabled. The study sheds light on good or bad regions for multi-touch, and also the type of input most appropriate for each of these regions. Second, guided by the results from our study, we explore the design space of multi-touch-integrated desktop experiences. A set of new interaction techniques are coherently integrated into a desktop prototype, called Magic Desk, demonstrating potential uses for multi-touch enabled desktop configurations.

RearType: text entry using keys on the back of a device

RearType is a text input system for mobile devices such as Tablet PCs, using normal keyboard keys but on the reverse side of the device. The standard QWERTY layout is split and rotated so that hands gripping the device from either side have the usual keys under the fingers. This frees up the front of the device, maximizing the use of the display for visual output, eliminating the need for an onscreen keyboard and the resulting hand occlusion, and providing tactile and multi-finger text entry - with potential for knowledge transfer from QWERTY. Using a prototype implementation which includes software visualization of the keys to assist with learning, we conducted a study to explore the initial learning curve for RearType. With one hours training, RearType typing speed was an average 15 WPM, and was not statistically different to a touchscreen keyboard.

Effects of interior bezels of tiled-monitor large displays on visual search, tunnel steering, and target selection

Tiled-monitor large displays are widely used in various application domains. However, how their interior bezels affect user performance and behavior has not been fully understood. We conducted three controlled experiments to investigate effects of tiled-monitor interior bezels on visual search, straight-tunnel steering, and target selection tasks. The conclusions of our paper are: 1) interior bezels do not affect visual search time nor error rate; however, splitting objects across bezels is detrimental to search accuracy, 2) interior bezels are detrimental to straight-tunnel steering, but not to target selection. In addition, we discuss how inte-rior bezels affect user behaviors, and suggest guidelines for effectively using tiled-monitor large displays and designing user interfaces suited to them.

Multilingual Touchscreen Keyboard Design and Optimization

A keyboard design, once adopted, tends to have a longlasting and worldwide impact on daily user experience. There is a substantial body of research on touch-screen stylus keyboard optimization. Most of it has focused on English only. Applying rigorous mathematical optimization methods and addressing diacritic character design issues, this article expands this body of work to French, Spanish, German, and Chinese. More important and counter to the intuition that optimization by nature is necessarily specific to each language, this article demonstrates that it is possible to find common layouts that are highly optimized across multiple languages for stylus (or single finger) typing. We first obtained a layout that is highly optimized for both English and French input. We then obtained a layout that is optimized for English, French, Spanish, German, and Chinese pinyin simultaneously, reducing its stylus travel distance to about half of QWERTYs for all of the five languages. In comparison to QWERTYs 3.31, 3.51, 3.7, 3.26, and 3.85 keys of movement for English, French, Spanish, German, and Chinese, respectively, the optimized multilingual layout has an average travel distance of 1.88, 1.86, 1.91, 1.77, and 1.68 keys, correspondingly. Applying Fittss law with parameters validated by a word tapping experiment, we show that these multilingual keyboards also significantly reduce text input time for multiple languages over the standard QWERTY for experienced users. In comparison to layouts individually optimized for each language, which are also obtained in this article, simultaneously optimizing for multiple languages caused only a minor performance degradation for each language. This surprising result could help to reduce the burden of multilingual users having to switch and learn new layouts for different languages. In addition, we also present and analyze multiple ways of incorporating diacritic characters on multilingual keyboards. Taken together, the present work provides a quantitative foundation for the understanding and designing of multilingual touch-screen keyboards.

Informal information gathering techniques for active reading

GatherReader is a prototype e-reader with both pen and multi-touch input that illustrates several interesting design trade-offs to fluidly interleave content consumption behaviors (reading and flipping through pages) with information gathering and informal organization activities geared to active reading tasks. These choices include (1) relaxed precision for casual specification of scope; (2) multiple object collection via a visual clipboard; (3) flexible workflow via deferred action; and (4) complementary use of pen+touch. Our design affords active reading by limiting the transaction costs for secondary subtasks, while keeping users in the flow of the primary task of reading itself.

Acquiring and pointing: an empirical study of pen-tilt-based interaction

Research literature has shown that pen tilt is a promising input modality in pen-based interaction. However, the human capability to control pen tilt has not been fully evaluated. This paper systematically investigates the human ability to perform discrete target selection tasks by varying the stylus tilt angle through two controlled experiments: pen tilt target acquiring (Experiment 1) and tilt pointing (Experiment 2). Results revealed a decreasing power relationship between angular width and selection time in Experiment 1. The results of Experiment 2 confirmed that pen tilt pointing can be modeled by Fitts law. Based on our quantitative analysis, we discuss the human ability to control pen tilt and the implications of pen tilt use. We also propose a taxonomy of pen tilt based interaction techniques and showcase a series of possible pen tilt technique designs.

Natural use profiles for the pen: an empirical exploration of pressure, tilt, and azimuth

Inherent pen input modalities such as tip pressure, tilt and azimuth (PTA) have been extensively used as additional input channels in pen-based interactions. We conducted a study to investigate the natural use profiles of PTA, which describes the features of PTA in the course of normal pen use such as writing and drawing. First, the study reveals the ranges of PTA in normal pen use, which can distinguish pen events accidently occurring in normal drawing and writing from those used for mode switch. The natural use profiles also show that azimuth is least likely to cause false pen mode switching while tip pressure is most likely to cause false pen mode switching. Second, the study reveals correlations among various modalities, indicating that pressure plus azimuth is superior to other pairs for dual-modality control.