User tasks for evaluation: untangling the terminology throughout visualization design and development.

User tasks play a pivotal role in evaluation throughout visualization design and development. However, the term 'task' is used ambiguously within the visualization community. In this position paper, we critically analyze the relevant literature and systematically compare definitions for 'task' and the usage of related terminology. In doing so, we identify a three-dimensional conceptual space of user tasks in visualization. Using these dimensions, visualization researchers can better formulate their contributions which helps advance visualization as a whole.