Paradiddle: minimizing input latency in mobile text entry
In this paper, we present design and evaluation of Paradiddle, a tap-based one-handed text-entry method. Paradiddle is designed to support mobile text entry for applications in which the total time to enter text—the time spent grasping the device, correctly positioning one's fingers, entering the text itself, and putting the device away—may be more important than raw speed. We describe this tradeoff in terms of the borrowed concepts latency and bandwidth. Like many text-entry systems, Paradiddle uses quick taps to select letters, but Paradiddle distinguishes taps not primarily by position on the user interface surface, but rather by the finger that performed the tap. An experiment shows that Paradiddle provides efficiency and learnability comparable to several competing techniques, although there are clear avenues for improving Paradiddle along both dimensions. We also argue that Paradiddle's low-latency design better supports the kind of text-entry commonly found in mobile environments.
Lee, S.; Newman, M. ; Partridge, K . Paradiddle: minimizing input latency in mobile text entry. PARC TR-2007-3. 2007 July.