ABSTRACT
Advances in computer technology and graphics have made it possible to produce powerful visualizations of scientific phenomena and more abstract information. This chapter describes visualization, very broadly, as any visual-spatial display in which information is communicated by the spatial arrangement of elements in the representation. Visualizations often depict physical phenomena that are spatial in nature, such as the development of a thunderstorm. They can also depict more abstract phenomena, such as the flow of information in a computer program or the organization of information on the world wide web. The chapter aims to explore possible relationships between internal and external visualizations and their role in thinking and reasoning. One possibility is that external visualizations can substitute for internal visualizations. A second possibility is that external visualizations augment internal visualizations, that is, provide information or insights that are additional to those that can be provided by internal visualizations.
