1 Two Characters per Stroke - A Novel Pen-Based Text Input Technique Natalie Jhaveri New Interaction Techniques 2003 Department of Computer and Information Sciences University of Tampere, Finland

2 Research Problem Designers have applied the pen technique for hand-held devices in the same way that we use a mouse: tap = click. They overlooked the two disticive actions of a pen (i.e. stylus): touch down and lift. These actions together constitute a stroke. In fact, drawing a stroke is a fast and natural gesture 1 in handwriting, which is of course the source of the pen as a utensil for input. To determine whether the Two Characters per Stroke technique could be: a) useful and b) faster than the conventional one character per tap technique for pen-based text entry.

3 Background Quikwriting Quikwriting: Continuous Stylus-based Text Entry 2 stylus never needs to be lifted from the surface user never needs to stop moving the stylus

4 Background (contd) T-cube T-cube: A fast, self- disclosing pen-based alphabet 3 Allows the user to encode each character as a short flicking gesture in one of 8 possible directions, from one of 9 locations. Figure: T-Cube pie menu structure 2nd level menu [7]

5 Background (contd) MessageEase To enter text on MessagEase for Palm Pilot use a single tap for the most frequent letters and a single drag for all other letters, numbers, and special characters.

6 Objectives & Research Methods And empirical study will be carried out whereby tests use a fully- functional version of each of the two stylus-based text entry techniques: 1) the Two Characters per Stroke technique 2) the conventional one character per tap technique Although, the ultimate objective is to compare the typing speed (in wpm) of the two techniques, the text-entry errors will also be taken into account when analyzing the results.

7 Schedule ActivityTimeResults Preliminary workWeek 6 - 9Research model and design Usability TestingWeeks Data Data AnalysisWeeks Results of usability testing Writing project reportWeek 15First draft of paper Revising paperWeek 17Final paper

8 The Specifics of the Two Characters per Stroke technique Each key on the traditional QWERTY keyboard layout is augmented with an additional 8 characters. In this way users can select a certain key and also a secondary character when lifting the pen, thereby selecting 2 charactesr in one stroke. The same set of most frequent characters is available from each key. (This is more obvious with the Finnish layout - vowels only : a e i o u ä ö) In this technique, the secondary characters are hidden and therefore, none of the keyboard is ever hidden from the users view. Furthermore, the keyboard never visibly changes from the conventional QWERTY keyboard layout (thereby avoiding distraction).

9 The Specifics of the Two Characters per Stroke technique

10 Experimental Setup 8 subjects Each subject completes a given phrase with each technique on the Compaq iPAC Pocket PC Each subject completes: 8 trials with the Two Characters per Stroke technique 2 trials with the conventional single tap technique This difference is done intentionally to account for the learning-effect Each subject is given a 10 minute learning period with the new technique

11 Summary of Expected Results Stylus text entry model: The model predicts a typing rate of 8.9 wpm for novices unfamiliar with the QWERTY keyboard, and 30.1 wpm for experts. 4 It is hypothesized, that after the initial learning curve is surpassed, this new technique will be faster than the more traditional method. However, it is also expected that this technique will also be accompanied with increased typing errors.

12 References 1. Geissler, J. Gedrics: the next generation of icons. Proceedings of the 5th International Conference on Human–Computer Interaction (INTERACT95), Lillehammer, Norway, June 27–29, 1995, pp. 73– K. Perlin. Quikwriting: Continuous stylus-based text entry. In Proc. of UIST '98. ACM, November D.Venolia and F.Neiburg. T-cube: Afast, self-disclosing pen-based alphabet. In Proc. of CHI 94, pages 265–270. SIGCHI, ACM, Soukoreff, R. W. & MacKenzie, I. S. (1995). Theoretical upper and lower bounds on typing speed using a stylus and soft keyboard. Behaviour & Information Technology, 14, MacKenzie, I. S., Zhang, S. X., & Soukoreff, R. W. (1999). Text entry using soft keyboards. Behaviour & Information Technology, 18, Aoki, P. M., Hurst, A. and Woodruff, A. (2001). Tap Tips: Lightweight Discovery of Touchscreen Targets. CHI 2001, Seattle. 7. MacKenzie, I. S., and Soukoreff, R. W. Text entry for mobile computing: Models and methods, theory and practice, Human-Computer Interaction (2002), [to appear].