Can smooth view transitions facilitate perceptual constancy in node-link diagrams?

Many visualizations use smoothly animated transitions to help the user interact with information structures. These transitions are intended to preserve perceptual constancy during viewpoint transformations. However, animated transitions also have costs -- they increase the transition time, and they can be complicated to implement -- and it is not clear whether the benefits of smooth transitions outweigh the costs. In order to quantify these benefits, we carried out two experiments that explore the effects of smooth transitions. In the first study, subjects were asked to determine whether graph nodes were connected, and navigated the graph either with or without smooth scene transitions. In the second study, participants were asked to identify the overall structure of a tree after navigating the tree through a viewport that either did or did not use smooth transitions for view changes. The results of both experiments show that smooth transitions can have dramatic benefits for user performance -- for example, participants in smooth transition conditions made half the errors of the discrete-movement conditions. In addition, short transitions were found to be as effective as long ones, suggesting that some of the costs of animations can be avoided. These studies give empirical evidence on the benefits of smooth transitions, and provide guidelines about when designers should use them in visualization systems.