Poster

Touchscreen smart phones can be operated in portrait (P) and landscape (L) orientation. However, whether a device is faster to operate in P or L and where to put a button in each layout for best findability and operability remains unclear. This research makes a first attempt to examine in which orientation a touch-operated interface is faster to use and whether certain “zones’” can be identified that have a particularly good performance in either orientation. Our results indicate that such zones exist in both L and P, and that L is faster to use than P. However, the effects are only visible when the user has not been primed with the target name. We conclude our study with practical advice for designers to improve usability and efficiency of time-critical applications and dialogues.