Development of visual and auditory exploration and perception with low-birth-weight infants is studied over the first weeks and months of life. The effects of exposure to hospital stimulation programs that provide increased levels of stimulation or increased exposure to learning experiences is studied in "high risk" populations of infants. Learning procedures during the hospitalization period will provide assessments of dimensions of visual and linguistic stimuli that support positive exploration by the low-birth-weight newborn. Findings from these studies will provide a rationale for developing stimulation programs that are appropriate for the sensory and perceptual capacities of these infants. Relationships between individual S differences in early perceptual discriminations of simple stimulus features of visual and speech stimuli and later differences in capacities for higher levels of perceptual processing are studied. Relations between information processing on perceptual tasks in the first months of life and intellectual performance at two years are being studied. Comparative developmental studies of short-term memory and selective attention mechanisms of full-term and low-birth-weight infants are being conducted.