User performance on typing tasks involving reduced-size, touch screen keyboards

The prospect of using a touch screen to interact with navigation displays led us to develop and evaluate three reduced-size, touch screen keyboards. One keyboard had a standard QWERTY layout; another had a modified QWERTY layout with keys aligned in a matrix; the third had a matrix of keys arranged in alphabetical order. Twenty adults varying in age and typing ability participated in the evaluation. Test results showed that subjects typed 25-26% faster on the QWERTY keyboards than on the alphabetical keyboard. The difference in typing speed between the two QWERTY keyboards was not significant. Additionally, differences in error rates among the three keyboards were not significantly different. Eleven out of 20 subjects preferred the standard QWERTY keyboard; 6 preferred the modified QWERTY keyboard; 3 preferred the alphabetical keyboard. These test results suggest that a reduced-size keyboard should employ a standard QWERTY key arrangement to achieve maximum usability.