How to Overcome Disorientation in Mobile Phone Menus: A Comparison of Two Different Types of Navigation Aids

Abstract

The current study was concerned with the basic question of how to overcome users' disorientation when navigating through hierarchical menus in small-screen technical devices, as for example mobile phones. In these devices, menu functions are typically organized in a tree structure. Two different navigation aids were implemented into a computer simulation of a real mobile phone (Siemens S45®). The interface of the first navigation aid (the "category" aid) showed the name of the current category as well as a list of its contents. The interface of the other navigation aid (the "tree" aid) was identical to the first except that it also showed the parents and parent–parents of the current of the category and it indented the subcategories to emphasize the hierarchical structure. For the study, 16 younger (23–28 years) and 16 older adults (46–60 years) had to solve 9 common phone tasks twice consecutively to measure learnability. To gain further insight into user characteristics modulating navigation performance and possibly interacting with the utility of the navigation aids, we assessed users' verbal memory and spatial abilities. Dependent variables were task effectiveness (number of tasks solved) and efficiency (time on task, number of returns in menu hierarchy, and returns to the top). The results reveal a consistent and significant advantage of the tree aid for both age groups, an advantage that was larger for users with lower spatial abilities and older adults. In general, older adults had lower verbal memory and spatial abilities, which were found to account for their lower navigation performance. We assume that the strong advantage of the tree aid is due to the spatial information on the menu structure, which thus conveys survey knowledge. This allows users to form an adequate mental representation of the menu. It is recommended to add a navigation aid providing survey knowledge into the displays of small-screen devices to achieve better overall performance.