A Study on the Effect of Design Factors of Slim Keyboard’s Tactile Feedback

Authors: Kai-Chieh Lin, Chih-Fu Wu, Hsiang Ling Hsu, Yung-Hsiang Tu, Chia-Chen Wu

Abstract:

With the rapid development of computer technology, the design of computers and keyboards moves towards a trend of slimness. The change of mobile input devices directly influences users’ behavior. Although multi-touch applications allow entering texts through a virtual keyboard, the performance, feedback, and comfortableness of the technology is inferior to traditional keyboard, and while manufacturers launch mobile touch keyboards and projection keyboards, the performance has not been satisfying. Therefore, this study discussed the design factors of slim pressure-sensitive keyboards. The factors were evaluated with an objective (accuracy and speed) and a subjective evaluation (operability, recognition, feedback, and difficulty) depending on the shape (circle, rectangle, and L-shaped), thickness (flat, 3mm, and 6mm), and force (35±10g, 60±10g, and 85±10g) of the keyboard. Moreover, MANOVA and Taguchi methods (regarding signal-to-noise ratios) were conducted to find the optimal level of each design factor. The research participants, by their typing speed (30 words/ minute), were divided in two groups. Considering the multitude of variables and levels, the experiments were implemented using the fractional factorial design. A representative model of the research samples were established for input task testing. The findings of this study showed that participants with low typing speed primarily relied on vision to recognize the keys, and those with high typing speed relied on tactile feedback that was affected by the thickness and force of the keys. In the objective and subjective evaluation, a combination of keyboard design factors that might result in higher performance and satisfaction was identified (L-shaped, 3mm, and 60±10g) as the optimal combination. The learning curve was analyzed to make a comparison with a traditional standard keyboard to investigate the influence of user experience on keyboard operation. The research results indicated the optimal combination provided input performance to inferior to a standard keyboard. The results could serve as a reference for the development of related products in industry and for applying comprehensively to touch devices and input interfaces which are interacted with people.

Keywords: Input performance, mobile device, slim keyboard, tactile feedback.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1112147

References:

[1] comScore, “TabLens: Today’s U.S. tablet owner revealed,” Retrieved from http://www.comscore.com/Insights/Press_Releases/2012/8/comScore_T abLens-Today_s_US_Tablet_Owner_Revealed, 2012.
[2] Sears, A. & Shneiderman, B., “High precision touchscreens: design strategies and comparisons with a mouse,” International Journal of Man-Machine Studies, vol. 34, no. 4, pp. 593-613, 1991.
[3] Wigdor, D. & Wixon, D., Brave NUI world: Designing natural user interfaces, Morgan-Kaufmann, Burlington, MA. 2011.
[4] Varcholik, P. D., Laviola Jr. J. J., & Hughes C. E., “Establishing a baseline for text entry for a multi-touch virtual keyboard,” International Journal of Human-Computer Studies, vol. 70, pp. 657-672, 2012.
[5] Fu, C. W., Goh, W. B. & Ng, J. A., “Multi-touch techniques for exploring large-scale 3D astrophysical simulations,” Proceedings of the 28th International Conference on Human Factors in Computing Systems, ACM, Atlanta, Georgia, USA, 2010.
[6] Google, “Tablet Survey March 2011,” Retrieved from http://services.google.com/fh/files/blogs/AdMob%20-%20Tablet%20Su rvey.pdf, 2011.
[7] Müller, H., Gove, J., & Webb, J., “Understanding tablet use: A multi-method exploration,” Proceedings of the 14th international conference on human-computer interaction with mobile devices and services, 2012, pp. 1-10, ACM.
[8] MacKenzie, I.S., Zhang, S.X., & Soukoreff, R.W., “Text entry using soft keyboards,” Behaviour and Information Technology, vol. 18, no. 4, pp. 235–244, 1999.
[9] Wu, C. F., Lien, C. M., & Kuo, F. C., “Performance study of the tangible keyboard and touch keyboard operation,” International Journal of Kansei Information, vol. 4, no. 1, pp. 21-28, 2013.
[10] MacKenzie, I.S., Nonnecke, B., McQueen, C., Riddersma, S., & Meltz, M., “Alphanumeric entry on pen-based computers,” International Journal of Human-Computer Studies, vol. 41, pp. 775–792, 1994.
[11] MacKenzie, I.S., & Zhang, S.X., “An empirical investigation of the novice experience with soft keyboards,” Behaviour and Information Technology, vol. 20, no. 6, pp. 411–418, 2001.
[12] MacKenzie, I.S., & Soukoreff, R.W., “Text entry for mobile computing: models and methods, theory and practice,” Human–Computer Interaction, vol. 17, no. 2 and no. 3, pp. 147–198, 2002a.
[13] MacKenzie, I.S., & Soukoreff, R.W., “A model of two-thumb text entry,” Graphics Interface, pp. 117–124, 2002b.
[14] MacKenzie, I.S., & Soukoreff, R.W., “Phrase sets for evaluating text entry techniques,” CHI ’03 extended abstracts on human factors in computing systems, ACM, Ft. Lauderdale, Florida, USA, 2003.
[15] Okayasu, K., Iwanaga, K., Harada, H., & Katsuura, T., “Interface design using tactile detection: Key shapes as input devices,” Proceedings of the Annual Conference of JSSD, vol. 45, 1998, pp. 122-123.
[16] Deininger, R. L., “Human factors engineering studies of the design and use of pushbutton telephone sets,” The Bell Systems Technical Journal, vol. 39, pp. 995-1012, 1960.
[17] Kinkead, R. D. & Gonzalez, B. K., Human factors design recommendations for touch-operated keyboards - final report (Document 12091-FR), Minneapolis, MN: Honeywell, Inc., 1969.
[18] Lai, C. C. & Wu, C. F., “Display and device size effects on the usability of mini-notebooks (netbooks)/ ultraportables as small form-factor Mobile PCs,” Applied Ergonomics, vol. 45, no. 4, pp. 1-10, 2014.
[19] 3G Technology Inc., “Principles of slim keyboard design,” Retrieved from http://www.3gi.com.tw/about.asp, 2013.
[20] Box, G. E., & Wilson, K. B., “On the experimental attainment of optimum conditions,” Journal of the Royal Statistical Society, Series B (Methodological), vol. 13, no. 1, pp. 1-45, 1951.
[21] Burdick, R. K., Borror, C. M., & Montgomery, D. C., Design and analysis of Gauge R and R studies: making decisions with confidence intervals in random and mixed ANOVA models, 2005, ch. 17, SIAM.
[22] Wobbrock, J. O., Measures of text entry performance, 2007, pp. 47-74, San Francisco: Morgan Kaufmann.
[23] Cohen, K. M., “Human Factors and Behavioral Science: Membrane keyboards and human performance,” The Bell System Technical Journal, vol. 62, no. 6, pp. 1733-1749, 1982.
[24] Pollard, D. & Cooper, M. B., “The effect of feedback on keying performance,” Applied Ergonomics, vol. 10, no.4, pp. 194-200, 1979.
[25] Pereira, A., Lee, D. L., Sadeeshkumar, H., Laroche, C., Odell, D., Rempel, D., “The effect of keyboard key spacing on typing speed, error, usability, and biomechanics: part 1,” Human Factors: The Journal of the Human Factors and Ergonomics Society, vol. 55, no. 3, pp. 557-566, 2013.
[26] Loricchio, D., “Key force and typing performance,” Proceedings of the Human Factors Society 36th Annual Meeting, 1992, pp. 281-282, Santa Monica, CA: Human Factors Society.
[27] Akagi, K., “A computer keyboard key feel study in performance and preference,” Proceedings of the Human Factors Society 36th Annual Meeting, 1992, pp. 523-527. Santa Monica, CA: Human Factors Society.
[28] Lewis, J. R., Potosnak, K. M., & Magyar, R. L., Handbook of human-computer interaction (2nd edition), 1997, pp. 1285-1315.