The primary goal of this research is to examine the effects of experience on the development of selected perceptual-cognitive abilities in infant pigtailed monkeys. Investigators have described the development of visual recognition, cross-modal transfer, and spatial perception in human and macaque monkey infants. It is clear from this body of research that (1) perceptual-cognitive development during infancy is very similar between humans and macaques, and (2) that infants are capable of discriminating, recognizing and responding to many features of their environment. There is a accumulating evidence that both human and monkey infants considered to be high risk for later cognitive impairment are less capable than their normal counterparts of processing information and learning about the world. High-risk and normal infants perform differently on a range of perceptual- cognitive tasks, and in humans, some of these measures have been found to predict future intellectual functioning. Very little is known about the role of experience on the development of perceptual-cognitive abilities. Such knowledge is important for understanding how infants acquire and process information and for designing effective intervention strategies for high-risk human infants. In the present study, monkey infants will be reared for the first two months of life in special cages which restrict visual access to the environment via a face-mask. This will allow for the control of visual experience from birth in order to examine some specific environmental components underlying early perceptual-cognitive development. One group of animals will be reared with both tactual and visual input but will not be allowed to integrate the information across the two modalities. In a second condition, animals will be prevented from associating binocular and kinetic information with cues for pictorial depth. At the end of the restrictive-rearing period, subjects will be administered a battery of tests focusing on cross-modal associative learning during the first months of life is necessary for the development of these abilities. The results also will provide preliminary information on the degree of plasticity of key perceptual-cognitive processes, and whether there are periods during infancy that require specific environmental input of normal development to occur.