The Tapwriter
The Tapwriter keyboard is a text entry interface that is optimized for fast typing with a single pointer such as a finger, pen, computer mouse, or eye gaze. It is suitable for very small displays such as seen on cellphones, palmtops, and wearable computers (e.g., a form-factor like a wristwatch), as well as for handicapped-access devices.
Background & Objective: With the rise of internet connectivity, it will be necessary to provide some means of text entry for small computing platforms such as cell-phones. Our goal is to design a text-entry interface that maximizes the speed of hunt-and-peck typing but minimizes real estate.
Technical Discussion: English text contains roughly 1 bit of information per character; if asked to predict the next character in a text, you can use the context (spelling, grammar, meaning) to whittle down the alphabet to an average of 2 or 3 possible completions. The Tapwriter uses machine learning methods to reduce typing to a choice between two or three alternatives. These are highlighted, as shown in the picture ("n" and "r" are highlighted after the user has written "eve"). The user can then make a choice with a pointer or a small number of buttons. Â Â Because the layout is unfamiliar, variable length Markov models are used to predict what the user will type next. The choices are highlighted to lead the eye to them, to reduce hunting time. The predictions are correct 76% of the time for normal English text. Novice users can write 40-80 characters per minute with the Tapwriter, as fast as expert typists can write using the familiar layout of the QWERTY keyboard on a pen-based device such as a PalmPilot. With practice one can tap-type faster than 140 characters/minute, roughly half the speed of touch-typing. The Tapwriter can also suggest completions of words (shown in white to the right of the cursor), based on the user's habitual language.
Technology Areas:
Artificial Intelligence
Off the Desktop Interaction and Display
Modification Date: July 14, 2004