Improving Novice Performance on the Twiddler One–Handed Chording Keyboard

The Twiddler one–handed chording keyboard offers rapid mobile text entry on a keypad similar to that of a standard mobile telephone. Previously we found that novice users could be trained to type 47 words per minute (wpm) while one participant reached 67 wpm. Here, we present an evaluation designed to examine which combination of two typing aids helps novice Twiddler typists the most. Specifically, we examine the effects of a phrase set designed for the Twiddler and the manipulation of an on–screen keymap representation. Sixty participants were divided across 6 conditions and typed for two 20 minute sessions. We found that, where there is an effect, using our ordered phrase set aids novice Twiddler typists’ typing rate, error rate and mental workload. Highlighting our on–screen representation helps typing speed, accuracy, and reduces workload.