The multi-touch-based pinch to zoom, drag and flick to pan metaphor has gained wide popularity on mobile displays, where it is the paradigm of choice for navigating 2D documents. But is finger-based navigation really the gold standard' In this paper, we present a comprehensive user study with 40 participants, in which we systematically compared the Pinch-Drag-Flick approach with a technique that relies on spatial manipulation, such as lifting a display up/down to zoom. While we solely considered known techniques, we put considerable effort in implementing both input strategies on popular consumer hardware (iPhone, iPad). Our results show that spatial manipulation can significantly outperform traditional Pinch-Drag-Flick. Given the carefully optimized prototypes, we are confident to have found strong arguments that future generations of mobile devices could rely much more on spatial interaction principles.

Lightweight spatially aware displays (Tangible Magic Lenses) are an effective approach for exploring complex information spaces within a tabletop environment. One way of using the 3D space above a horizontal surface is to divide it into discrete parallel layers stacked upon each other. Horizontal and vertical lens movements are essential tasks for the style of multi-layer interaction associated with it. We conducted a comprehensive user study with 18 participants investigating fundamental issues such as optimal number of layers and their thickness, movement and holding accuracies, and physical boundaries of the interaction volume. Findings include a rather limited overall interaction height (44 cm), a different minimal layer thickness for vertical and horizontal search tasks (1 cm/4 cm), a reasonable maximum number of layers depending on the primary task, and a convenience zone in the middle for horizontal search. Derived from that, design guidelines are also presented.