The One-key Challenge: Searching for a Fast One-key Text Entry Method

I. Scott MacKenzie

Eleventh International ACM SIGACCESS Conference on Computers and Accessibility (ASSETS 2009)
Pittsburgh, PA, USA, October 26-28, 2009

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Abstract

A new one-key text entry method is presented. SAK, for "scanning ambiguous keyboard", combines one-key physical input (including error correction) with three virtual letter keys and a SPACE key. The virtual letter keys are highlighted in sequence ("scanned") and selected when the key bearing the desired letter receives focus. There is only one selection per letter. Selecting SPACE transfers scanning to a word-selection region, which presents a list of candidate words. A novel feature of SAK is multiple-letter-selection in a single scanning interval. In an evaluation with 12 participants, average entry speeds reached 5.11 wpm (all trials, 99% accuracy) or 7.03 wpm (error-free trials). A modification using "timer restart on selection" allowed for more time and more selections per scanning interval. One participant performed extended trials (5 blocks x 5 phrases/block) with the modification and reached an average entry speed of 9.28 wpm.