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Scrolling interactions are an important aspect of the design of usable touchscreen interfaces, particularly for handheld devices that can only display a limited amount of information at once. Using a touchscreen capable of dynamically altering its surface friction, we explore the design space of haptically-augmented scrolling interactions and investigate programmable friction's ability to provide appropriate feedback in envisioned usage scenarios. We performed five user experiments to evaluate respectively the identifiability of a set of iconic detents, the countability of detents, the perception of detent density, the synchronization of tactile feedback to on-screen events, and the optimal friction pattern for a spring-like resistance. The results of these experiments provide valuable information that will inform the design of scrolling interactions that leverage programmable friction for an improved user experience.

We investigate gains in user appreciation and performance when the level of detail of tactile graphics is dynamically altered either at the press of a button or automatically, as a function of exploration speed. This concept was evaluated by asking 9 visually impaired participants to perform hierarchical spatial search tasks in a concert hall illustration. The tasks could be simplified by first searching for a section in a sparse illustration, and then a seat in a detailed illustration. The results show no improvement in task performance but indicate a user preference for explicitly controlling the level of details with the manual toggle.