  Massively multiplayer online role-playing games create virtual communities
that support heterogeneous "social roles" determined by gameplay interaction
behaviors under a specific social context. For all social roles, formal roles
are pre-defined, obvious, and explicitly ascribed to the people holding the
roles, whereas informal roles are not well-defined and unspoken. Identifying
the informal roles and understanding their subtle changes are critical to
designing sociability mechanisms. However, it is nontrivial to understand the
existence and evolution of such roles due to their loosely defined,
interconvertible, and dynamic characteristics. We propose a visual analytics
system, RoleSeer, to investigate informal roles from the perspectives of
behavioral interactions and depict their dynamic interconversions and
transitions. Two cases, experts' feedback, and a user study suggest that
RoleSeer helps interpret the identified informal roles and explore the patterns
behind role changes. We see our approach's potential in investigating informal
roles in a broader range of social games.
