Abstract
In this paper, we describe the result of an experiment we conduct at our Department meant to understand which visual representation between two-dimensional or three-dimensional icon arrangements is better for stimulating the user mental model in order to recognize topological relationships. The experiment has involved two groups of 10 subjects to which we have submitted some tasks representing common topological relationships. The experiment consisted in two sessions During the first session, for each task we asked users to assign a score indicating how much the task may be represented by each arrangement, then we calculated the existing correlation between the approaches. Resulting values show that using three-dimensional icons there are no significant improvements in efficacy with respect to bi-dimensional iconic arrangements. However, the second session of the experiment revealed that the degree of user's satisfaction may be positively influenced by the use of three-dimensional icons.