Publisher Summary This chapter examines the way animating a viewpoint change in a spatial information system affects a user's ability to build a mental map of the information in the space. It is found that animation improves users' ability to reconstruct the information space, with no penalty on task performance time. One potential drawback of adding animation to an interface or visualization is that animation takes time. This brings up a fundamental trade-off between the time spent animating and the time spent using the interface. Animation has a strong visual impact and not all users like it. So, future studies should be careful to consider user satisfaction as well as performance. If a task requires subjects to know something about objects' spatial position and the viewpoint is changed, then animating that change in viewpoint appears to helps users. Zoomable user interfaces (ZUIs) are a visualization technique that provides access to spatially organized information.