Many of the current concepts on the mechanisms of binocular vision and amblyopia have been developed from physiological studies on animals. It is important to compare psychophysical data from these species with human data in order to provide a more direct link between the physiology and behavior of humans. This paper describes behavioral experiments on rhesus monkeys with normal binocular vision and monkeys with experimental amblyopia. The visual functions investigated were stereopsis, fusional vergence ranges, spatial contrast sensitivity, and increment-threshold spectral sensitivity. The comparison of data from human observers with those of the monkeys shows remarkable agreement. The monkey is useful as a surrogate for experiments that are either impossible or impractical to conduct on humans, and the data may be applied to the human population.