Interacting with Visualizations

Interactive visualization is a process made up of a number of interlocking feedback loops that fall into three broad classes. At the lowest level is the data manipulation loop, through which objects are selected and moved using the basic skills of eye-hand coordination. Delays of even a fraction of a second in this interaction cycle can seriously disrupt the performance of higher-level tasks. At an intermediate level is an exploration and navigation loop, through which an analyst finds his or her way in a large visual data space. As people explore a new town, they build a cognitive spatial model using key landmarks and paths between them; something similar occurs when they explore data spaces. This chapter explains how to make the graphic interface as fluid and transparent as possible. Doing so involves supporting eye-hand coordination, using well-chosen interaction metaphors, and providing rapid and consistent feedback. Of course, transparency comes from practice. For instance, a violin has an extraordinarily difficult user interface, and to reach virtuosity may take thousands of hours, but once virtuosity is achieved, the instrument will have become a transparent medium of expression.