The function of vision is to provide information to the observer in order to facilitate subsequent action on the environment. Accurate perception entails discernment of the boundaries, coherence, and unity of objects. This process is challenged by the fact that many objects are partly occluded by other, nearer objects. Successful object completion under conditions of partial occlusion resides in the appropriate attention to and utilization of several sources of visual information, such as the luminance, color, texture, motion, and depth of visible surfaces. A complete account of object perception must include studies of its development, and recent research has contributed important information to our knowledge in this area. Interestingly, at birth infants seem to respond to a partly occluded object as if it consists of two disjoint surfaces, even if it provides a clear percept of unity to adults. By 2 months of age, in contrast, infants have been found to perceive object unity under some circumstances, and this skill improves over the following months. Thus humans are not born with the ability to perceive object unity, but it develops very rapidly over the first few months. At present there are disagreements among researchers with respect to the mechanisms of development of perception of object unity. For example, young infants have been claimed to rely exclusively on motion, and not other cues such as surface appearance, to disambiguate visual scenes involving partial occlusion. Other approaches invoke "core principles" that guide object perception from birth, such that the perceptual experience of bounded, segregated objects is shared by all human observers, even very young infants. Recent research, however, provides evidence against both these views: Young infants, like adults, appear to rely on several sources of visual information in object perception tasks, including motion as well as surface orientation, color, texture, and depth. On this account, the development of veridical responses to objects proceeds via improvements in the utilization of all these cues. Despite this advance in theoretical approaches to the development of object perception, important questions remain. The present research will investigate issues surrounding how infants respond to the depth and segregation of objects in their environment. The goal is to further elucidate the constraints that guide this fundamental perceptual skill in the first few months after birth. This will be accomplished by testing the role of specific visual cues in young infants' perception of object unity, as well as explorations of young infants' visual scanning of object displays, to chart developmental changes in attention to visual cues.
