Surface ghosts: Promoting awareness of transferred objects during pick-and-drop transfer in multi-surface environments

Rekimoto's Pick-and-Drop (P&D) transfer technique is commonly used to support multi-surface object transfer (e.g., between a shared tabletop and tablet) due to its easily understood metaphor of emulating object movement in the physical world. Current multi-surface implementations of P&D provide little to no feedback during transfer, causing confusion for the person performing the action as well as others in the environment. To address this issue, we investigated the use of virtual embodiments to improve awareness of transferred objects, in the context of a real-world group task that relied heavily on cross-device transfer. An iterative design process led to the design of Surface Ghosts virtual embodiments, which take the form of semitransparent "ghosts" of the transferred objects displayed under the "owner's" hand on the tabletop during transfer. A user study that compared two Surface Ghosts designs- varied by how explicitly the "owner" was indicated- showed that both designs improved awareness of transferred objects when compared to a no-feedback control condition, especially for tabletop-to-tablet transfers.