Plaisant, C., Sears, A. (Sept. 1991)
In cases when only limited alphanumeric data must be entered, or when layout, labeling, or size may be changed, traditional keyboards may not be optimal. A series of experiments has demonstrated the usability of touchscreen keyboards. We give a summary of the existing data concerning the usability of touchscreen keyboards including typing rates for experts and novices on keyboards of various sizes. We also report on a recent study done with representative users. Results indicate that typing rates inc rease rapidly reaching peak performance after only 25 minutes of use. Practical suggestions for the design of such a keyboard are also presented.