On devices such as mobile phones, text is often entered using keypads and predictive text entry techniques. Current metrics used for measuring text entry error rates have limitations in terms of the types of errors they account for, and cannot easily distinguish between different types of errors. This research proposes a new text entry error metric that addresses some of the outstanding issues that exist with current metrics. Specifically, the metric accounts in detail for the way the user handles corrections during text entry, moving beyond current keystroke level error measurement. The feasibility and usefulness of this new metric is shown through the analysis of an experiment that tests an alphabetically constrained keypad design that includes upper and lower case letters, numbers, and punctuation marks.

The creation of text will remain a necessary part of human-computer interaction with mobile devices, even as they continue to shrink in size. On mobile phones, text is often entered using keypads and predictive text entry techniques, which attempt to minimize the effort (e.g., number of key presses) needed to enter words. This research presents results from the design and testing of alphabetically-constrained keypads, optimized on various word lists, for predictive text entry on mobile devices. Complete enumeration and Genetic Algorithm-based heuristics were used to find keypad designs based on different numbers of keys. Results show that alphabetically-constrained designs can be found that are close to unconstrained designs in terms of performance. User testing supports the hypothesis that novice ease of learning, usability, and performance is greater for constrained designs when compared to unconstrained designs. The effect of different word lists on keypad design and performance is also discussed.

The Enhanced Restricted Focus Viewer (ERFV) is a unique software tool for tracking the visual attention of users in hyperlinked environments, such as Web sites. The software collects data, such as mouse clicks along with the path of users' visual attention, as they browse a site. Unlike traditional eye-tracking procedures, the ERFV requires no hardware to operate other than a personal computer. In addition to time and cost savings, the ERFV allows the administration of usability testing to groups of participants simultaneously. A laboratory test comparing the ERFV to a hardware-based eye-tracking system showed that the two methods compared favorably in terms of how well they track a user's visual attention. The value of the ERFV as a usability testing tool was demonstrated through an experiment that evaluated two Web sites that were equivalent in content but that differed in terms of design. Although several open issues concerning the ERFV still remain, some of these issues are being addressed through ongoing research efforts.