Text entry on mobile devices (e.g., phones and PDAs) has been a research challenge since devices shrank below laptop size: mobile devices are simply too small to have a traditional full-size keyboard. There has been a profusion of research into text-entry techniques for smaller keyboards and stylus input: some of which have become mainstream, while others have not lived up to early expectations. This chapter will review the range of input techniques, together with evaluations, that have taken place to assess their validity: from theoretical modelling through to formal usability experiments. Finally, the chapter will discuss criteria for acceptance of new techniques, and how market perceptions can overrule laboratory successes.
Key Terms in this Chapter
Usability Techniques: Series of methods and tools for designing and evaluating the usefulness and effectiveness of a text-entry system.
Evaluation: Method for assessing and measuring the performance of a text-entry system in terms of either usability or technical performance.
Handwriting Recognition: Method for interpreting text that has been entered using handwriting via stylus
Text Entry: Method of inputting text to a mobile device
Ambiguous Keyboards: A keyboard layout where each key is related to many letters (e.g., the standard 12-key phone pad layout where, say, 2 is mapped to ABC)
Predictive Text Entry: Text-entry method that attempts to predict the user’s intended words from an ambiguous input (sometimes extended to predict word or phrase completions).
Unambiguous Keyboards: A keyboard layout where one key-press unambiguously relates to one character (e.g., 2 is mapped to A)
User Studies: Evaluations that are conducted to assess the performance of a system with real end users, generally conducted in usability laboratories under controlled settings.