UNLABELLED Even when we view an object from different distances, so that the size of its projection onto the retina varies, we perceive its size to be relatively unchanged. In this perceptual phenomenon known as size constancy, the brain uses both distance and retinal image size to estimate the size of an object. Given that binocular disparity, the small positional difference between the retina...

Contemporary studies of visual perception often view the observer's problem as one of estimation. In other words, the observer seeks to estimate various aspects of the scene, such as the size and shape of the objects in that scene. The information available to inform this estimation is viewed as consisting of one or more visual cues. Each cue may be used on its own to estimate some aspects of s...

purpose: to compare the refractive results of penetrating keratoplasty (pk) in two groups of patients with keratoconus undergoing corneal grafting with different amounts of donor-recipient disparity (0.25 and 0.5 mm). methods: as a randomized clinical trial and after performing a complete ocular examination and vitreous length measurement, 30 patients with keratoconus were randomly assigned in ...

We examined whether binocular saccadic eye movements are determined solely by disparity-defined slant or whether they are influenced by both disparity-defined and perceived slant. The Werner illusion was used to distinguish a plane's disparity-defined slant from its perceived slant. Three subjects viewed a horizontally elongated test strip that was flanked vertically by two planes. The perceive...

Task directed, active vision techniques are beginning to produce vision systems capable of providing real-time depth perception for robots. The concepts of shallow disparity filters and coarse disparity segmentation show particular promise for several reasons: they require minimal correlation search, thus they are fast; they employ redundant measurements, so they are noise tolerant; and they ar...

Binocular fixation is achieved by rotating the eyes, but this process also transforms the pattern of image disparities. This effect is problematic for biological visual systems, in which stereopsis is based on simple, short-range mechanisms. It is argued here that the problem should be addressed in two ways; firstly by an appropriate representation of disparity, and secondly by modelling the ty...

Horizontal binocular disparity is the fundamental stimulus for both fusional vergence and stereopsis, but whether common disparity-sensitive mechanisms are involved in both responses is unknown. To determine whether the sensitivities of motor and sensory fusion are interdependent, we studied vergence eye movements and depth discrimination, using stimuli with haplopic binocular disparities, in s...

We investigated over what central area disparity in a random dot stereogram is integrated to stimulate an initial vergence response. Vergence was measured subjectively, with a forced choice dichoptic nonius vernier task following a brief (230 msec) stimulus presentation. Stimuli were random-dot stereograms showing a central circular disc of 12.5 min arc crossed retinal disparity in front of, an...