Exploring Optimal Placement of Head-Based Hierarchical Marking Menus on Smartphones

Studies have shown that hierarchical marking menus, which allow for the navigation of menu items through a hierarchy, are faster at accessing items compared to traditional menus. Though hierarchical marking menus have been studied in non-touch-based input methods for smart devices (such as gaze-based input with VR), little is known about optimal menu placement in hierarchical structures for smartphones. In this paper, we investigate the optimal placement of subsequent marking menus within a menu hierarchy utilizing head-based input on smartphones. We examine how to position a second menu by considering the distances and directions from the first menu while examining two selection techniques: Dwell and Border Crossing. Results from a user study involving menu item selection tasks reveal that users are faster at selecting items when the second menu partially overlaps the first menu and appears in the direction where the target in the first menu is located. Furthermore, results showed that while Dwell was slower than Border Crossing, it resulted in significantly fewer errors in selecting items in the hierarchical menu. Based on these findings, we provide design guidelines for placing menus in the hierarchical marking menu setting.