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

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.

Authors:

• Kai-Chieh Lin
• Chih-Fu Wu
• Hsiang Ling Hsu
• Yung-Hsiang Tu
• Chia-Chen Wu

Keywords:

• Input performance
• mobile device
• slim keyboard
• tactile feedback.

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.