Publication statistics

Pub. period:2005-2012
Pub. count:11
Number of co-authors:22


Number of publications with 3 favourite co-authors:

Ravin Balakrishnan:4
Shumin Zhai:3
Barton A. Smith:2



Productive colleagues

Xiaojun Bi's 3 most productive colleagues in number of publications:

Ravin Balakrishnan:108
Shumin Zhai:67
Ken Hinckley:54

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Xiaojun Bi


Publications by Xiaojun Bi (bibliography)

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Bi, Xiaojun, Smith, Barton A. and Zhai, Shumin (2012): Multilingual Touchscreen Keyboard Design and Optimization. In Eminds International Journal of Human Computer Interaction, 27 (4) pp. 352-382. Available online

A keyboard design, once adopted, tends to have a long-lasting 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 QWERTY's for all of the five languages. In comparison to QWERTY's 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 Fitts's 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.

© All rights reserved Bi et al. and/or Universidad de Oviedo

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Bi, Xiaojun, Chelba, Ciprian, Ouyang, Tom, Partridge, Kurt and Zhai, Shumin (2012): Bimanual gesture keyboard. In: Proceedings of the 2012 ACM Symposium on User Interface Software and Technology 2012. pp. 137-146. Available online

Gesture keyboards represent an increasingly popular way to input text on mobile devices today. However, current gesture keyboards are exclusively unimanual. To take advantage of the capability of modern multi-touch screens, we created a novel bimanual gesture text entry system, extending the gesture keyboard paradigm from one finger to multiple fingers. To address the complexity of recognizing bimanual gesture, we designed and implemented two related interaction methods, finger-release and space-required, both based on a new multi-stroke gesture recognition algorithm. A formal experiment showed that bimanual gesture behaviors were easy to learn. They improved comfort and reduced the physical demand relative to unimanual gestures on tablets. The results indicated that these new gesture keyboards were valuable complements to unimanual gesture and regular typing keyboards.

© All rights reserved Bi et al. and/or ACM Press

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Xin, Yizhong, Bi, Xiaojun and Ren, Xiangshi (2011): Acquiring and pointing: an empirical study of pen-tilt-based interaction. In: Proceedings of ACM CHI 2011 Conference on Human Factors in Computing Systems 2011. pp. 849-858. Available online

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.

© All rights reserved Xin et al. and/or their publisher

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Bi, Xiaojun, Grossman, Tovi, Matejka, Justin and Fitzmaurice, George (2011): Magic desk: bringing multi-touch surfaces into desktop work. In: Proceedings of ACM CHI 2011 Conference on Human Factors in Computing Systems 2011. pp. 2511-2520. Available online

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.

© All rights reserved Bi et al. and/or their publisher

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Scott, James, Izadi, Shahram, Rezai, Leila Sadat, Ruszkowski, Dominika, Bi, Xiaojun and Balakrishnan, Ravin (2010): RearType: text entry using keys on the back of a device. In: Proceedings of 12th Conference on Human-computer interaction with mobile devices and services 2010. pp. 171-180. Available online

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 hour's training, RearType typing speed was an average 15 WPM, and was not statistically different to a touchscreen keyboard.

© All rights reserved Scott et al. and/or their publisher

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Bi, Xiaojun, Bae, Seok-Hyung and Balakrishnan, Ravin (2010): Effects of interior bezels of tiled-monitor large displays on visual search, tunnel steering, and target selection. In: Proceedings of ACM CHI 2010 Conference on Human Factors in Computing Systems 2010. pp. 65-74. Available online

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 interior bezels affect user behaviors, and suggest guidelines for effectively using tiled-monitor large displays and designing user interfaces suited to them.

© All rights reserved Bi et al. and/or their publisher

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Bi, Xiaojun, Smith, Barton A. and Zhai, Shumin (2010): Quasi-qwerty soft keyboard optimization. In: Proceedings of ACM CHI 2010 Conference on Human Factors in Computing Systems 2010. pp. 283-286. Available online

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 user's 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.

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Bi, Xiaojun and Balakrishnan, Ravin (2009): Comparing usage of a large high-resolution display to single or dual desktop displays for daily work. In: Proceedings of ACM CHI 2009 Conference on Human Factors in Computing Systems 2009. pp. 1005-1014. Available online

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 more immersive 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.

© All rights reserved Bi and Balakrishnan and/or ACM Press

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Bi, Xiaojun, Moscovich, Tomer, Ramos, Gonzalo, Balakrishnan, Ravin and Hinckley, Ken (2008): An exploration of pen rolling for pen-based interaction. In: Cousins, Steve B. and Beaudouin-Lafon, Michel (eds.) Proceedings of the 21st Annual ACM Symposium on User Interface Software and Technology October 19-22, 2008, Monterey, CA, USA. pp. 191-200. Available online

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Bi, Xiaojun, Shi, Yuanchun and Chen, Xiaojie (2006): uPen: A Smart Pen-liked Device for Facilitating Interaction on Large Displays. In: First IEEE International Workshop on Horizontal Interactive Human-Computer Systems Tabletop 2006 5-7 January, 2006, Adelaide, Australia. pp. 160-168. Available online

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Bi, Xiaojun, Shi, Yuanchun, Chen, Xiaojie and Xiang, Peifeng (2005): uPen: laser-based, personalized, multi-user interaction on large displays. In: Zhang, Hongjiang, Chua, Tat-Seng, Steinmetz, Ralf, Kankanhalli, Mohan S. and Wilcox, Lynn (eds.) Proceedings of the 13th ACM International Conference on Multimedia November 6-11, 2005, Singapore. pp. 1049-1050. Available online

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