Investigation of keyboard and speech based text entry on mobile devices
Abstract
This work presents four in-depth empirical investigations on the performance and user
experience of three popular mainstream mobile text entry methods: Touch Typing on a
Software Keyboard (STK), the Gesture Typing on a Software Keyboard (SGK), and
Speech Based Text Entry. The first and third studies are lab-based longitudinal text
entry experiments. In the second and fourth studies, we use a new text entry evaluation
methodology based on the experience sampling method (ESM). In the ESM based
studies, participants installed an Android app on their own mobile phones that
periodically sampled their text entry performance and user experience amid their
everyday activities for four weeks. The studies show that text can be entered at an
average speed of 24 to 41 WPM using software keyboards, and 49 to 59 WPM using
speech, depending on the method and the user's experience, with 0.9% to 3.6%
character error rates remaining for software keyboard and 3.0% to 5.8% for speech.
Error rates of SGK and speech based input are a major challenge; and reducing out-of-vocabulary errors is particularly important. Both typing and speech have strengths,
weaknesses, and different individual awareness and preferences. Two-thumb touch
typing in a focused setting is particularly effective on STK, whereas one-handed SGK
typing with the thumb is particularly effective in more mobile situations. Speech is
more effective when convenience and constraints take priority, whereas typing is more
preferable in public – due to social concerns, network latency issues and background
noise. When exposed, users showed a trend to migrate from STK to SGK. We also
conclude that studies in the lab and in the wild can both be informative to reveal
different aspects of keyboard and speech based text entry, but used in conjunction is
more reliable in comprehensively assessing input technologies of current and future
generations.
Type
Thesis, PhD Doctor of Philosophy
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