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GI 2002 Online Papers



A Model of Two-Thumb Text Entry

Scott MacKenzie and William Soukoreff

Abstract

Although text entry has been extensively studied for touch typing on standard keyboards and finger and stylus input on soft keyboards, no such work exists for two-thumb text entry on miniature Qwerty keyboards. In this paper, we propose a model for this mode of text entry. The model provides a behavioural description of the interaction as well as a predicted text entry rate in words per minute. The prediction obtained is 60.74 words per minute. The prediction is based solely on the linguistic and motor components of the task; thus, it is a peak rate for expert text entry. A detailed sensitivity analysis is included to examine the effect of changing the model's components and parameters over a broad range (+/-50% for the parameters). The model demonstrates reasonable stability - predictions remain within about 10% of the value just cited.

The Paper

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