Modeling Hierarchical Menu Selections: Effects of Additive Factors

In this paper we demonstrate that models of hierarchical menu selections should include a component that accounts for additive factors (AF) associated with sub-selections (selections on each menu level). Examples of such AF are dwell time, mouse clicks, or reaction time of pointing movements. We collect empirical data from 28 participants using two considerably different hierarchical menu designs. The results show that the effects of AF associated with sub-selections are substantial and models not accounting for it lose their value because they cannot explain the sources of the differences between tested designs. We also use the collected data to compare performance of the designs and propose a simple measure of performance stability assessing the degree of navigation problems.