User interface metaphors for a PDA operating system

This study proposes three novel organizing metaphors for PDA operating system: ‘personal computer’, ‘day planner’, and ‘gadgets in a bag’. Eighteen initial metaphor candidates were generated from a user survey. The initial metaphor candidates were screened to reduce the number of finally prototyped metaphors that were used in an evaluation experiment. A user-involved experiment was conducted to examine the usability of three final metaphors, ‘personal computer’, ‘day planner’ and ‘gadgets in a bag’ in addition to the existing ‘Pocket PC OS’. The metaphor type and learning factors were manipulated in the experiment. Number of clicks, task completion time, and number of errors were measured while the subjects were performing function search tasks. Subjective usability scores and overall satisfaction were also gathered after each treatment condition. The results showed that the day planner metaphor was proved superior in terms of the objective measures, i.e., the number of clicks, task completion time, and the number of errors. Meanwhile, with respect to the subjective measures (i.e., metaphor usability score and overall satisfaction), the three metaphors (i.e., personal computer, day planner, gadgets in a bag) were better than the Pocket PC OS. This study showed that the usability of the existing Pocket PC OS can be improved by introducing a new organizing metaphor appropriate to the PDA. The metaphors proposed in this study are expected to provide valuable insight into the design of future PDA operating systems and application programs. The usability of a personal mobile device such as a PDA can be improved by adopting an appropriate user interface metaphor. The metaphors proposed in this study may be considered as an alternative organizing metaphor when developing a new operating system for those devices.