Physical-Digital Privacy Interfaces for Mixed Reality Collaboration: An Exploratory Study.

We present a study exploring privacy behaviours in mixed reality collaborative environments. We consider two scenarios involving hiding and sharing blended physical-virtual documents around a tabletop, under two vertical display conditions: a solo display showing the remote collaborator as an avatar, and circumambient displays showing the rest of the connected virtual environment. We explore four types of cues (interactive, communication-based, ambient, and infrastructure) and their impact on how collaborators hide and share blended physical-virtual documents. Many participants did not obviously develop a sense that the physical and virtual surroundings were fused; as a result, certain physical privacy behaviours (e.g., orienting one's body to shield documents from the remote collaborator) were less apparent in the study. However, the circumambient displays generated curiosity about how the spaces were connected, and episodes where breaches were enacted or the spatial correlation was otherwise suggested led some participants to trust the environment less. On the table, the presence of fiducial markers and digital document \"shadows\" served to cue participants about the impact of hiding and sharing physical documents, however accidental breaches usually went unnoticed.