Metaphors of human thinking for usability inspection and design

Usability inspection techniques are widely used, but few focus on users' thinking and many are appropriate only for particular devices and use contexts. We present a new technique (MOT) that guides inspection by metaphors of human thinking. The metaphors concern habit, the stream of thought, awareness and associations, the relation between utterances and thought, and knowing. The main novelty of MOT is its psychological basis combined with its use of metaphors to stimulate inspection. The first of three experiments shows that usability problems uncovered with MOT are more serious and more complex to repair than problems found with heuristic evaluation. Problems found with MOT are also judged more likely to persist for expert users. The second experiment shows that MOT finds more problems than cognitive walkthrough, and has a wider coverage of a reference collection of usability problems. Participants prefer using MOT over cognitive walkthrough; an important reason being the wider scope of MOT. The third experiment compares MOT, cognitive walkthrough, and think aloud testing, in the context of nontraditional user interfaces. Participants prefer using think aloud testing, but identify few problems with that technique that are not found also with MOT or cognitive walkthrough. MOT identifies more problems than the other techniques. Across experiments and measures of usability problems' utility in systems design, MOT performs better than existing inspection techniques and is comparable to think aloud testing.