Influence of difference in monocular contrasts on perception of an object in 3-d visual space

It is important to know whether the binocular 3-D space perception is available without geometrical cues. In this regard, the paper deals with the question, whether the differences in monocular contrast of the object images at the left and right retina affect the perceived direction and depth of the object in space. The binocular analyzer model, introduced in the paper, consists of a set of local analyzers (LA) and the global one. LA determines the centroid of the light distribution over its receptive fi eld and identifies the coordinates of the centroid in the local coordinate system of the given analyzer. There are separate on- and offanalyzers, which send information independently to the input of the global system, where the location of the objects in visual space is determined. LA has four Gabor like monocular neurons in the left and right eye separately (or in monocular channels). These neurons obtain information from the joint receptive field which is located in the corresponding areas of the retina of the left and right eyes. Three binocular neurons algebraically sum up the output signals of the identical monocular Gabor neurons located in different retina. The values of these three binocular signals determine the components of 3-D vector, the orientation of which identifies two spatial coordinates (parallax and depth) of an object (similar as color saturation and hue are determined by 3-D color vector). The identified coordinates of a centroid depend not only on the monocular coordinates of two centroids but also on contrasts of monocular images. The introduced binocular analyzer model predicts that the impact of the contrast on the “perceived” location of the object also depends on the position of the object in visual space. For example, the contrast doesn’t impact the identified parallax (or visual direction) when the object is located on the longitudinal horopter. But if an object is on the cyclopean axis, the impact on the “perceived” direction is maximal. Conversely the contrast does not impact the determined depth of an object locating on this axis. These predictions coincide with the experimental data presented in the paper. Moreover the simulating shows that the stereoacuity of the model exponentially decreases when object is moving away from the fixation point alongthe cyclopean axis. This prediction also coincides with data obtained by other authors experimentally.