Efficient keyboard layouts for sequential access in augmentative and alternative communication

Abstract

The study evaluated the efficiency, measured in typing speed (duration/character) and communication rate (sentence completion time and words/minute), of eight different keyboard layouts using a sequential scanning access method. The two 12-key keyboards tested contained three characters on each key with the second and third characters accessed with a two-key combination. Simulated conversational utterances were used as input to the keyboards and a custom computer program calculated the time and keystroke requirements of each keyboard for each sentence. The 43-key letter-frequency-based arrangement was the most efficient among the keyboards tested, followed closely by 12-key letter-frequency, 43-key alphabetical, and 12- key alphabetical keyboards. The modified QWERTY keyboards were, in comparison, grossly less efficient. The results also show that row-column scanning is nearly twice as fast as linear scanning for all keyboards. Implications of these findings for clinicians and for augmentative and alternative communication users are discussed.