A psychophysical comparison of two stylus-driven soft keyboards

Abstract

This study compared text entry performance of two stylus-driven soft keyboards for use in hand-held computing devices: the QWERTY and the T9. Participants transcribed text presented on a computer screen into a personal digital assistant (PDA) using a stylus and one of these two keyboards. We introduced a new psychophysical technique for measuring transcription rate that provides a composite measure of speed and accuracy. Using this technique, we calculated the maximum transcription rate for each keyboard. The results show that transcription rates were higher for the QWERTY keyboard than for the T9, despite the T9 keyboard's apparent superior physical characteristics. An ancillary experiment demonstrated that the poorer performance of the T9 layout may have resulted from an increase in visual scanning time due to perceptual grouping of the letters on the keys. Together these findings imply that the QWERTY keyboard layout remains the most effective of the currently available designs for stylus tapping on soft keyboards.