In this chapter, we have discussed a variety of empirical studies concerning various aspects of information visualization, ranging from the usage of classic information visualization designs such as cone trees and hyperbolic view browsers to individual differences in terms of spatial ability, associative memory, and visual memory.
Much of the existing empirical studies can be divided into ones that deal with lower-level elementary perceptual tasks or higher-level application-related tasks. Although information visualization can no doubt benefit from all empirical studies, the crucial and profound understanding at this stage is more likely to come from the study of lower-level tasks. Many application-oriented empirical studies have generated valuable insights into the complex relationship between tasks and visual cues. On the other hand, the empirical link between visual attributes and perceptual tasks is still missing in many areas of information visualization.