Overview

Consider the eyeball as an information-gathering searchlight, sweeping the visual world under the guidance of the cognitive centers that control our attention. Information is acquired in bursts, a snapshot for each fixation. From an image buffer, the massively parallel machinery of early visual processing finds objects based on salient features of images. Once identified, complex objects are scanned in series, one after another, in a much slower process. Understanding the steps in this process can help us with many visualization tasks. Here are some examples.

Often a computer program should attract the user's attention. For example, most people sometimes want to be interrupted when an important email arrives. Such a user interruption is often achieved using sound, but it may also be accomplished visually.

A tactical map display used by a military strategist must simultaneously show many different kinds of information about resources, such as equipment and personnel, and environmental conditions that exist in the field. Ideally, with such a display it should be possible either to attend to a single aspect of the data, such as the deployment of tanks, or, by an act of visual attention, to perceive the whole complex interwoven pattern. Understanding early vision is critical in understanding how to make information visually distinct or to make the integrated patterns stand out.

In a scatter plot, each plotted data point can be made to represent many different kinds of information by using a glyph instead of an undifferentiated circle. A glyph is a graphical...