Perceptual Grouping: It's Later Than You Think

Recent research on perceptual grouping is described with particular emphasis on the level at which grouping factors operate. Contrary to the standard view of grouping as an early, two-dimensional, image-based process, experimental results show that it is strongly influenced by binocular depth perception, lightness constancy, amodal completion, and illusory figures. Such findings imply that at least some grouping processes operate at the level of conscious perception rather than the retinal image. Whether classical grouping processes also operate at an early, preconstancy level is an important, but currently unanswered question.