The proposed research will study the development of motion sensitive mechanisms in the human visual system over the first five postnatal months. Motion sensitivity will be isolated from position sensitivity using a psychophysical technique first employed by Nakayama and Tyler (1981) to isolate such mechanisms in adults. Transverse standing wave oscillation of thin lines at low temporal frequencies is used to isolate motion sensitive mechanisms. Converging evidence will be obtained using both angularly rotating lines and traveling waves. These experiments provide point predictions for discriminating between detection by motion sensitive versus position sensitive mechanisms. Several of the experiments also examine evidence for the aperture problem in the infant's visual system. The experiments will provide normative data on motion sensitivity and its development during early postnatal life.