Fast text-entry on miniature mobile devices

Abstract As mobile messaging devices are becoming smaller, for example wristwatches with Internet connectivity, there is less space for keys. Researchers have experimented with 3-key text input devices and come up with designs allowing text to be entered with as little as 4.23 keystrokes per character, but the strategies are hard to use. This paper demonstrates a dictionary-enhanced technique, which allows text to be entered using 2.16 keystroke per character. Four approaches are investigated — a ring-based method, a two-level tree-based method, a multi-tap method and a one-stroke method. Experiments are used to evaluate the usability of the approaches and the results confirm that there is a trade-off between usability and number of keystrokes per characters. The results show that the multi-ring approach requires less concentration from the user than previous strategies while text is entered with just 3.2 keystrokes per character.