Graffiti vs. unistrokes: an empirical comparison

ABSTRACT

Unistrokes and Graffiti are stylus-based text entry techniques. While Unistrokes is recognized in academia, Graffiti is commercially prevalent in PDAs. Though numerous studies have investigated the usability of Graffiti, none exists to compare its long-term performance with that of Unistrokes. This paper presents a longitudinal study comparing entry speed, correction rate, stroke duration, and preparation (i.e., inter-stroke) time of these two techniques. Over twenty fifteen-phrase sessions, performance increased from 4.0 wpm to 11.4 wpm for Graffiti and from 4.1 wpm to 15.8 wpm for Unistrokes. Correction rates were high for both techniques. However, rates for Graffiti remained relatively consistent at 26%, while those for Unistrokes decreased from 43% to 16%.

REFERENCES

• 1: Xiang Cao , Shumin Zhai, Modeling human performance of pen stroke gestures, Proceedings of the SIGCHI conference on Human factors in computing systems, April 28-May 03, 2007, San Jose, California, USA [doi>10.1145/1240624.1240850]
• 2: David Goldberg , Cate Richardson, Touch-typing with a stylus, Proceedings of the INTERACT '93 and CHI '93 conference on Human factors in computing systems, p.80-87, April 24-29, 1993, Amsterdam, The Netherlands [doi>10.1145/169059.169093]
• 3: I. Scott MacKenzie , Javier Chen , Aleks Oniszczak, Unipad: single stroke text entry with language-based acceleration, Proceedings of the 4th Nordic conference on Human-computer interaction: changing roles, p.78-85, October 14-18, 2006, Oslo, Norway [doi>10.1145/1182475.1182484]
• 4: I. Scott MacKenzie , R. William Soukoreff, Phrase sets for evaluating text entry techniques, CHI '03 extended abstracts on Human factors in computing systems, April 05-10, 2003, Ft. Lauderdale, Florida, USA [doi>10.1145/765891.765971]
• 5: MacKenzie, I. S. and Soukoreff, R. W. Text entry for mobile computing: Models and methods, theory and practice. In MacKenzie, I. S. ed., Human-computer interaction (2002), 147--198.
• 6: I. Scott MacKenzie , Shawn X. Zhang, The immediate usability of graffiti, Proceedings of the conference on Graphics interface '97, p.129-137, May 1997, Kelowna, British Columbia, Canada
• 7: Stroop, J. R. Studies of interference in serial verbal reactions. Journal of Experimental Psychology, 18. 643--662.
• 8: Yamada, H. A historical study of typewriters and typing methods: From the position of planning japanese parallels. Journal of Information Processing, 2 (4). 175--202.

INDEX TERMS

Primary Classification:
  H. Information Systems
  H.5 INFORMATION INTERFACES AND PRESENTATION (I.7)
      H.5.2 User Interfaces (D.2.2, H.1.2, I.3.6)
          Subjects: Evaluation/methodology

General Terms:
Human Factors, Performance

Keywords:
empirical study, graffiti, stylus, text entry, unistrokes