Showing papers on "Monocular vision published in 1995"

Binocular Vision and Stereopsis

Abstract: Introduction 1. Binocular correspondence and the horopter 2. Sensory coding 3. The physiology of binocular vision 4. The limits of stereoscopic vision 5. Matching corresponding images 6. Types of disparity 7. Binocular fusion and rivalry 8. Binocular masking and transfer 9. Vergence eye movements 10. Stereo constancy and depth cue interactions 11. Depth contrrast and cooperative processes 12. Spatiotemporal aspects of stereopsis 13. Vision in the cyclopean domain 14. Development and pathology of binocular vision 15. Binocular and stereoscopic vision in animals References Subject index

Adapting to Monocular Vision - Grasping with One Eye

Abstract: The aim of the present study was to determine whether normal subjects with one eye covered and patients in whom one eye had been enucleated generate more head movements than subjects using binocular vision during the performance of a visually guided grasping movement. In experiment 1, 14 right-handed normal subjects were tested binocularly and monocularly in a task in which they were required to reach out and grasp oblong blocks of different sizes at different distances. Although the typical binocular advantage in reaching and grasping was observed, the overall head movement scores did not differ between these testing conditions. In experiment 2, seven right-handed enucleated patients were compared to seven age and sex-matched control subjects (tested under binocular and monocular viewing conditions), on the same task as used in experiment 1. While no differences were found in the kinematics of reaches produced by the enucleated patients and the control subjects, the patients did produce larger and faster resultant head movements, composed mainly of lateral and vertical movements. This suggests that enucleated patients may be generating more head movements in order to better utilize retinal motion cues to aid in manual prehension.

Contrast coding by cells in the cat's striate cortex: monocular vs. binocular detection.

Abstract: Many psychophysical studies of various visual tasks show that performance is generally better for binocular than for monocular observation. To investigate the physiological basis of this binocular advantage, we have recorded, under monocular and binocular stimulation, contrast response functions for single cells in the striate cortex of anesthetized and paralyzed cats. We applied receiver operating characteristic analysis to our data to obtain monocular and binocular neurometric functions for each cell. A contrast threshold and a slope were extracted from each neurometric function and were compared for monocular and binocular stimulation. We found that contrast thresholds and slopes varied from cell to cell but, in general, binocular contrast thresholds were lower, and binocular slopes were steeper, than their monocular counterparts. The binocular advantage ratio, the ratio of monocular to binocular thresholds for individual cells, was, on average, slightly higher than the typical ratios reported in human psychophysics. No single rule appeared to account for the various degrees of binocular summation seen in individual cells. We also found that the proportion of cells likely to contribute to contrast detection increased with stimulus contrast. Less contrast was required under binocular than under monocular stimulation to obtain the same proportion of cells that contribute to contrast detection. Based on these results, we suggest that behavioral contrast detection is carried out by a small proportion of cells that are relatively sensitive to near-threshold contrasts. Contrast sensitivity functions (CSFs) for the cell population, estimated from this hypothesis, agree well with behavioral data in both the shape of the CSF and the ratio of binocular to monocular sensitivities. We conclude that binocular summation in behavioral contrast detection may be attributed to the binocular superiority in contrast sensitivity of a small proportion of cells which are responsible for threshold contrast detection.

Binocular expanded field of view spectacle mounted microscope

Abstract: A binocular expanded field of view spectacle mounted microscope including a single microscope provided in front of and mounted to a bridge of a spectacle frame, a first pair of optical path deflectors rotatably connected to the spectacle frame of each side of the bridge of the frame and projecting into a line of sight and visual axis in a direction of the microscope and a second pair of optical path deflectors mounted on the spectacle frame such that a line sight and visual axis from the microscope deflected by the first pair of optical path deflectors is directed towards each eye of a wearer whereby a field of view for each eye is partially overlapped by rotating the first pair of optical path deflectors to provide an expanded field of view including a single zone of binocular vision and a zone of monocular vision on each side of the single zone of binocular vision.

Analysis of camera movement errors in vision-based vehicle tracking

Abstract: When a camera is used to provide the navigational parameters in autonomous vehicle operations, it is subjected to unexpected movements or vibrations of the mounting platform This paper presents a framework for analyzing the effect of uncontrollable camera movements on the navigational parameters, in particular on the range and-heading angle in vision-based vehicle tracking The noise introduced by the platform movements is modeled in two ways: camera noise approach and image noise approach The parameter space of the camera is divided into a controllable subspace consisting of its height and depression angle, and an uncontrollable subspace consisting of the tracked object coordinates and rotation angle errors A consistent detectable region is then obtained such that the tracked object is always seen by the camera Based on this region, a reliable region consisting of no singularity points is established so that the range error does not become infinity The optimum parameters of the controllable subspace with respect to the uncontrollable subspace are found by employing two estimation schemes: (a) the mini-max estimator to provide the worst case effect, and (b) the minimum-mean-square estimator to provide the average or overall effect From the results obtained, it is shown how an optimum imaging geometry of a monocular vision-based tracking system can be designed in order to satisfy prescribed levels of range and heading angle errors >

Monocular contribution to the peak time of the binocular pattern-visual evoked potential

Abstract: The contribution of each monocular pathway to the timing of the binocular pattern visual evoked potential was assessed in situations where a significant interocular timing discrepancy was observed. Monocular and binocular pattern visual evoked potentials to 0.5° checks were recorded from normal subjects, normal subjects in whom one eye was blurred, patients with monocular amblyopia, and patients with resolved unilateral optic neuritis. Normal subjects showed facilitation, while suppression was evidenced in subjects with monocular blurring. In patients with amblyopia, the affected pathway had no effect on binocular pattern visual evoked potential latency, suggesting that the amblyopic eye was suppressed. In contrast, all patients with optic neuritis showed binocular averaging. Our results show that different forms of binocular interaction are evidenced in normal subjects, in amblyopia and in optic neuritis, and suggest that a comparative analysis of monocular and binocular pattern visual evoked potential peak times brings valuable information to the clinical evaluation that could be used to distinguish disease processes further.

A method to study changes in eye-related columns in the visual cortex of kittens during and following early periods of monocular deprivation

Abstract: An immunohistochemical method that exploits the rapid light-evoked expression of Fos, the protein product of the immediate early gene, c-fos, to visualize eye-related columns in the visual cortex, has been used to provide preliminary data on the relative innervation of the cortex by the two eyes of monocularly deprived kittens and the speed of the changes that occur afterward during reverse occlusion. In contrast to conventional anatomical techniques, the method allows both cellular resolution and documentation of the dimensions of eye-related columns through the depth of the cortex. In kittens monocularly deprived from near birth, Fos-immunoreactive neurones were observed in oval or circular patches, the size of which decreased as the duration of deprivation was increased from 4 to 6 weeks. Following reverse occlusion at 5 weeks of age, the size of the patches increased rapidly so that after 4 days their area had approximately tripled. In addition to providing possible insights into the anatomical underpinnings of the puzzling behavioural effects that occur following termination of short periods of reverse occlusion, the method can be used to investigate the temporal order of the anatomical effects of monocular deprivation in different cortical layers.

Visual suppression of one eye's view with dichoptic stimulation

Abstract: When the two eyes receive different stimulation (which can occur with artificial viewing devices), binocular single vision gives way to alternating periods of monocular suppression ; this outcome is termed binocular rivalry. This paper summarizes the conditions triggering rivalry and its accompanying visual consequences, with emphasis on aspects of visual processing that remain functional during monocular suppression.

Three-dimensional control of binocular eye movements in far and near vision

Abstract: Minken AWH, Lokate JMA, Van Gisbergen JAM (1992) Application of the equal innervation principle to the analysis of binocular eye movements in three dimensions. Soc Neurosa Abstr 18: p. 704 Minken AWH, Van Opstal AJ, Van Gisbergen JAM (1991) Validity of Listing's law in strongly curved saccades. Eur J Neurosa [suppl 14] p. 306 Van Gisbergen JAM, Minken AWH (1991 ) Rapid and slow mechanisms for the control of ocular torsion during voluntary gaze shifts. Soc Neurosa Abstr 17: p. 862 Van Gisbergen JAM, Minken AWH (1992) Limitations to the validity of Listing's law in near vision. Eur } Neurosa [suppl 15] p. 276