Sears, A., Revis, D., Swatski, S., Crittenden, R., Shneiderman, B. (April 1991)
This study investigated the effect keyboard size has on typing speed and error rates for touchscreen keyboards. Four keyboard sizes were investigated ranging from 24.5 cm to 6.8 cm wide (23% larger to 64% smaller than standard keyboards). Results indic ate that novices can type approximately 9 words per minute (WPM) on the smallest keyboard and 20 WPM on the largest. Users with moderate experience with the keyboards improved to 21 WPM on the smallest keyboard and 32 WPM on the largest. These results i ndicate that although slower, very small touchscreen keyboards are possible and can be used for limited data entry when the presence of a regular keyboard is not practical. Results also indicate the increased importance of experience on these smaller key boards. Possible research directions are suggested.