APA Dictionary of Psychology

any of a variety of means used to inform the visual system about the depth of a target or its distance from the observer. Monocular cues require only one eye and include signals about the state of the ciliary muscles, atmospheric perspective, linear perspective, and occlusion of distant objects by near objects. Binocular cues require integration of information from the two eyes and include signals about the convergence of the eyes and binocular disparity.