In this chapter we emphasized that visual information is used to distinguish objects from their backgrounds and to discriminate objects from one another. We presented various views of form perception, including structuralism, Gestalt psychology, and the multichannel model derived from measurements of the CSF. The multichannel model is an attempt to relate human form perception to what is known about the visual cortex. It can account for many aspects of human and animal vision, including detection, discrimination, and certain visual illusions, but it, too, has its limitations. In the next chapter, you'll learn how the visual system puts together the information it acquires to generate useful representations of objects.