Physical multi-touch spherical displays can provide a direct, hands-on, embodied interaction experience with global visualization data like ocean temperatures and currents. However, current commercially available displays may be cost-prohibitive for educational institutions and/or non-profits to acquire. Virtual globe-based visualizations like Google Earth are a potential alternative, but it is not clear how well the interactive affordances of physical spheres may transfer to the virtual. We conducted a within-subjects comparative study with 21 participants who completed similar tasks on a physical and a virtual spherical interface platform, which were designed to be as similar as possible, in order to allow us to compare the interaction experiences. Our results overall showed no significant difference be-tween usability or task time on the two platforms. In their qualitative feedback, participants noticed the differences between the physical sphere and virtual sphere in terms of effort and motor demand. Our research implies that, in resource-constrained environments, a virtual globe can be a sufficient substitute for a physical sphere from a usability perspective.

Multi-touch spherical displays that enable groups of people to collaboratively interact are increasingly being used in informal learning settings such as museums. Prior research on large flatscreen displays has examined group collaboration patterns in museum settings to inform the design of group learning experiences around these displays. However, previous research has shown differences in how users conceptualize interacting with spherical and flatscreen displays, thereby making it important to separately investigate how groups naturally collaborate around spherical displays in a museum setting. The spherical form factor of the display affords new forms of collaboration: unlike flatscreen displays, spherical displays do not have a definite front or center, thus intrinsically creating both shared and private touch interaction areas on the display based on users' viewing angles or physical arrangements. We conducted a 5-day long field study at a local science museum during which 571 visitors (370 adults and 201 children) in 211 groups interacted with a walk-up-and-use collaborative learning application showing global science data visualizations, on a multi-touch spherical display. We qualitatively analyzed groups' natural collaboration patterns including their physical arrangements (F-formations), their collaboration profiles (e.g., turn-taker or independent), and the nature of group discussion around the display. Our results show that groups often engaged in both independent as well as closely collaborative group explorations when interacting around the sphere: physical spacing between group members around the sphere was strongly linked to the way groups collaborated. It was less common for group members to make and accept suggestions or coordinate touch interactions when they did not share the same fields-of-view or touch interaction space with each other around the sphere. We discuss implications for supporting group collaboration in this context which will inform the design of future walk-up-and-use multi-touch spherical display applications for use in public settings.