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.

Interactive spherical displays offer numerous opportunities for engagement and education in public settings. Prior work established that users' touch-gesture patterns on spherical displays differ from those on flatscreen tabletops, and speculated that these differences stem from dissimilarity in how users conceptualize interactions with these two form factors. We analyzed think-aloud data collected during a gesture elicitation study to understand adults' and children's (ages 7 to 11) conceptual models of interaction with spherical displays and compared them to conceptual models of interaction with tabletop displays from prior work. Our findings confirm that the form factor strongly influenced users' mental models of interaction with the sphere. For example, participants conceptualized that the spherical display would respond to gestures in a similar way as real-world spherical objects like physical globes. Our work contributes new understanding of how users draw upon the perceived affordances of the sphere as well as prior touchscreen experience during their interactions.