Experiments are planned on questions of development and plasticity of vision. Two main approaches will be used. First, psychophysical tests will be conducted using subjects who have limited visual experience in one or both eyes. Second, experiments will be conducted using cats who have been reared with certain developmental anomalies. The latter studies involve neurophysiological techniques of single-cell analysis. The human work involves the study of amblyopia in several forms. Tests of visual acuities and contrast sensitivities will be made. The investigations using cats include paradigms of monocular deprivation and a search for mechanisms underlying effects found.