本研究探討手指在筆記型電腦觸控板上的移動行為，並據此設計觸控板之最佳動態控制顯示增量(CD gain)值，依據手指在觸控板上的速度變化量對觸控板的CD gain值進行動態調整可以讓使用者兼顧移動績效與達到較平滑順暢的移動。
本研究募集了40位使用者參與本次實驗，實驗於筆記型電腦上以費茲點擊作業，分別在不同的7組動態CD gain條件下，對不同目標物大小(10及70 pixel)、距離(100及650 pixel)以及角度(0°、90°、180°、270°)下進行，收集移動時間、移動次數、錯誤率及主觀問卷評比來進行後續的分析。
實驗結果顯示，這七組不同的CD gain顯著影響移動時間及移動次數。而在移動時間、移動次數、喜好程度、細部微調及速度感受統計下，我們可知使用者移動過程中，較不喜歡速度一下就切換太高的檔次，在手指加速至50 dot/12.5ms前，韌體準備切換至高速狀態時，建議CD gain以不超過2.5為原則。而本研究除了在探討使用者於觸控板上之使用經驗與行為並量化外，在動態gain值設定上，提供較佳的設計建議與驗證。

The touchpad is commonly known as a pointing device and is a predominant pointing technology for notebook computers. This study examined the effects of Control Display Gain change on the performance of the Fitts’ task . Subjective questionnaires were used to understand participants’ response in control adjustment and satisfaction under different CD gains.
40 participants were requested to use the touchpad with 7 different dynamic gains. The Fitts’ task was performed with 2 levels of distance (100,650 pixel), 2 levels of target width (10, 70 pixel), and 4 directions (0°, 90°, 180°, and 270°). The dependent variables were movement time, movement count, error rate in the Fitts’ task , and subjective rating of the questionnaire.
The result showed that the CD gain significantly affects movement time and movement count. The results of movement time, movement count, preference, detailed adjustment, and subjective feeling of velocity , show that when users used the finger to move on touchpad, they tended not to convert to high speed immediately. Therefore, we suggest the CD gain not to exceed 2.5, before the finger was accelerated to 50 dot/12.5ms, while the firmware of the touchpad is changing into high gain. Output of this study is the exploration of user experience in touchpad usage and behavior; also the value set in the dynamic gain that providing better advice and design verification.

1. Accot, J., and Zhai, S. (2003). Refining Fitts' law models for bivariate pointing. SIGCHI. April 5-10.
2. Akamatsu, M., MacKenzie, I. S. (2002). Changes in Applied Force to a Touchpad during Pointing Tasks. International Journal of Industrial Ergonomics 29, 171-182.
3. Arnaut, L. Y., and Greenstein, J. S. (1986). Optimizing the touch tablet: the effects of control-display gain and method of cursor control. Human Factors, 28 (6), 717-726.
4. Blanch, R., Guiard, Y., Beaudouin-Lafon, M., 2004. Semantic pointing: improving target acquisition with control-display ratio adaptation. Proceedings of the ACM CHI Conference on Human Factors in Computing Systems, pp. 519–525.
5. Casiez, G., Vogel, D., Balakrishnan, R., and Cockburn, A. (2008). The Impact of Control Display Gain on User Performance in Pointing Task. Human-Computer Interaction 23, 213-250.
6. Cockburn, A., Firth, A., 2003. Improving the acquisition of small targets. Proceedings of the British HCI Conference, pp. 181–196.
7. Douglas, S.A., Kirkpatrick, A.E., and MacKenzie, I.S.(1999). Testing pointing device performance and user assessment with the ISO 9241, Part 9 standard. In: ACM Conference in Human Factors in Computing Systems e CHI ’99, New York.
8. Fitts, P. M. (1954). The Information Capacity of the Human Motor System in Controlling the Amplitude of Movement. Journal of Experimental Psychology 47 (6), 381-391.
9. Gan, K-C., & Hoffmann, E. R. (1988). Geometrical conditions for ballistic and visually controlled movements. Ergonomics, 31, 829-839.
10. Hertzum, M., Hornbaek, K. (2005). TouchGrid: Touchpad Pointing by Recursively Mapping Taps to Smaller Display Recognition. Behaviour & Information Technology, vol 24, no 5, 337-346.
11. ISO 9241-11. (1998). Ergonomic requirements for office work with visual display terminals (VDT)s-Part 11 Guidance on usability, ISO 9241-11.
12. Jagacinski, R. J., Repperger, D. W., Moran, M. S., Ward, S. L., & Glass, B. (1980a). Fitts' law and the microstructure of rapid discrete movements.Journal of Experimental Psychology: Human Perception and Performance, 6, 309-320.
13. Jellinek H. D and Card, S. K. (1990). Powermice and User Performance. Proceedings of the CHI’s 90 Conference on Human Factors in Computing Systems. New York: ACM.
14. Johnsgard, T. (1994). Fitts’ Law with a Virtual Reality Glove and a Mouse: Effects of Gain. Graphics Interface 1994.
15. Johnson, P. E., Dropkin, J. J., Hews, J. & Remple, D. (1993). Office ergonomics: motion analysis of computer mouse usage. American Industrial Hygiene Conference and Exposition, 12-13.
16. Lee, Y. H., Wu, S. K., and Liu, Y. P. (2010). Performance of Remote Target Acquisition Hand Movements in a 3D environment, Human Movement Sciences, (SCI) (in reviewing).
17. MacKenzie, I. S. (1989). A note on the information-theoretic basis for Fitts' law. Journal of Motor Behavior, 21, 323-330.
18. MacKenzie, I., S. (1992). Fitts' law as a research and design tool in human-computer interaction. Human-Computer Interaction, 7:91-139.
19. MacKenzie, I. S. and Riddersma, S. (1994): Effects of Output Display and Control-Display Gain on Human Performance in Interactive Systems. In Behaviour and Information Technology, 13 (5) pp. 328-337.
20. MacNeill, D., Blickenstorfer, C. H. (1996). Trackpads: Alternative Input Technologies. Pen Computing 3, 42-45.
21. MacKenzie and Oniszczak. (1998). A Comparison of Three Selection Techniques for Touchpad. Proceedings of the CHI '98 Conference on Human Factors in Computing Systems, pp. 336-343 New York: ACM.
22. Puspasari, M. A. and Lee, Y. H. (2011). Factors Affecting Performance of Target Acquisition Task in Touchpad. Taiwan: National Taiwan University of Science and Technology.
23. Nielsen, J. (1993). Usability Engineering. Boston, Academic Press.
24. Sandfeld, J. and B.R. Jensen. (2005). Effect of computer mouse gain and visual demand on mouse clicking performance and muscle activation in a young and elderly group of experienced computer users, Applied Ergonomics, 36(5):547-555. September 2005, Pages 547-555.
25. Smyrnis, N., Evdokimidis, I., Constantinidis, T.S., Kastrinakis, G. (2000). Speed-accuracy trade-off in the performance of pointing movements in different directions in two-dimensional space. Experimental Brain Research, 134, 21–31.
26. Thompson, S.G., McConnell, D. S., Slocum, J. S., Bohan, M. (2007). Kinematic Analysis of Multiple Constraints on a Pointing Task. Human Movement Science 26, 11-26.
27. Walker, N., & Catrambone, R. (1993). Aggregation bias and the use of regression in evaluation models of human performance. Human Factors, 35, 397-411.
28. Whisenand, T.G. and Emurian, H.H. (1999). Analysis of cursor movement with a
mouse. Computers in Human Behavior, 15, 85-103.
29. Worden, A., Walker, N., Bharat, K. and Hudson, S. (1997). Making computers easier for older adults to use: area cursors and sticky icons. Proceedings of the ACM CHI Conference on Human Factors in Computing Systems, pp. 266–271.