Effects of arm embodiment on implicit coordination, co-presence, and awareness in mixed-focus distributed tabletop tasks.

Mixed-focus collaboration occurs when people work on individual tasks in a shared space -- and although their tasks may not be directly linked, they still need to maintain awareness and manage access to shared resources. This kind of collaboration is common on tables, where people often use the same space to carry out work that is only loosely coupled. At physical tables, people easily manage to coordinate access to the table surface and the artifacts on it, because people have years of experience interacting around other physical bodies. At distributed digital tabletops, however, where there is no physical body for the remote person, many of the natural cues used to manage mixed-focus collaboration are missing. To compensate, distributed groupware often uses digital embodiments. On digital touch tables, however, we know little about how these embodiments affect coordination and awareness. We carried out an empirical study of how four factors in an arm embodiment (transparency, input technique, visual fidelity, and tactile feedback) affected implicit coordination, awareness, and co-presence. We found that although some embodiments affected subjective feelings of co-presence or awareness, there were no changes in table behavior -- people acted as if the other person did not exist. These findings show the possibilities and limitations of digital arm embodiments, and suggest that the natural advantages of tables for collaboration may not extend to distributed tables.