A computational model for the control of horizontal vergence, based on a population of disparity tuned complex cells, is presented. Since the population is able to extract the disparity map only in a limited range, using the map to drive vergence control means to limit its functionality inside this range. The model directly extracts the disparity-vergence response by combining the outputs of th...

In the wallpaper illusion, a repetitive pattern appears to shift from one depth plane to the plane nearest fixation. We measured the timing of this shift for a 6 degrees wide, 3-cpd sinusoidal grating presented in a rectangular envelope; the edges (envelope) of the grating were presented at 20 arcmin of disparity (one period) behind the fixation plane. We asked observers to signal when the segm...

PURPOSE Variation in stereoacuity was examined in a large group of observers with Snellen acuity of 20/30 or less. METHODS Threshold retinal disparity for 2.78 degrees x 2.28 degrees rectangular test stimuli was determined as a function of the retinal disparity (varied from 55 arcmin uncrossed to 55 arcmin crossed) of a 5.57 degrees x 4.8 degrees rectangular pedestal stimulus in 160 observers...

Three-dimensional (3D) shape discrimination could be achieved using relative disparity signals or it could be achieved using a higher-order disparity derivative detector. Two 3D shape discrimination tasks were used to distinguish between these possibilities: a within-shape task and a between-shape task. Disparity thresholds were larger when discriminating within the same shape than when discrim...

Dissociated strabismus complex (DSC), comprising dissociated vertical deviation (DVD), dissociated horizontal deviation (DHD), and dissociated torsional deviation (DTD), is an enigmatic ocular misalignment disorder, for which multiple causes have been hypothesized. Evidence-based studies evaluating the pathophysiology of this unusual ocular motility disorder is of value to existing knowledge. L...

Although cortical activation to binocular disparity can be demonstrated throughout occipital and parietal cortices, the relative contributions to depth perception made by different human cortical areas have not been established. To investigate whether different regions are optimized for specific disparity ranges, we have measured the responses of occipital and parietal areas to different magnit...

Towards the centre of the human retina there is a small area called the fovea that is responsible for providing very high acuity visual information to the visual system. While visual information is available from areas other than the fovea, it is less rich in detail since acuity falls off very rapidly from the centre of the fovea to the retinal periphery (see Balota & Rayner, 1991). Thus, in or...

In the present work, we use random-dot stereograms to test a possible relationship between associated phoria and stereopsis. We determined, using a modified constant-stimulus method, the disparity range that indicates the maximum range at which stereoscopic correspondence can be achieved. A total of 27 observers took part in the experiment. The value of the disparity range as a function of the ...