Applied Ergonomics - rok 2010 , ročník 41

Small mobile devices are ubiquitous and must be designed with great care. One of the most serious challenges is how information on the small displays is presented optimally. This paper addresses the special problem of the increasing number of aged users. On the one hand, information displayed should be easily readable. This requires a low information density and a sufficiently large font size. On the other hand menu orientation is facilitated when the amount of information per screen is maximized and a large preview is allowed. This requires presenting as many functions as possible on the screen at a time. Thus, the tradeoff between readability and orientation demands is crucial. In the present study, this tradeoff was experimentally investigated. Two factors, font size (8 pt, 12 pt) and the size of the preview (one or five functions per screen at a time) were varied and effects on navigation performance were observed. Forty older participants solved nine common phone navigation tasks twice consecutively on a simulated mobile phone. Both factors contributed to performance, but there was a significant interaction: navigation performance was optimal when font size and the size of the preview were large. The lowest performance was obtained when the preview was small and the font size large, showing that proper orientation is more important than visibility demands. The results can be used in ergonomic guidelines to optimized information presentation on small screens.