Showing papers on "Monocular vision published in 2002"
TL;DR: The unexpectedly good results after monocular deprivation suggest that the higher centers involved in the integration of global motion profit from input to the nondeprived eye, and that beyond the primary visual cortex, competitive interactions between the eyes can give way to collaborative interactions that enable a relative sparing of some visual functions aftermonocular deprivation.
179 citations
TL;DR: The results suggest that monocular viewing is associated with preferential activation of attentional systems in the contralateral hemisphere, and that the right hemisphere (at least in right eye dominant subjects) is biased towards far space.
Abstract: Observations in primates and patients with unilateral spatial neglect have suggested that patching of the eye ipsilateral to the injury and contralateral to the neglected space can sometimes improve attention to the neglected space. Investigators have generally attributed the effects of monocular eye patching to activation of subcortical centers that interact with cortical attentional systems. Eye patching is thought to produce preferential activation of attentional systems contralateral to the viewing eye. In this study we examined the effect of monocular eye patching on attentional biases in normal subjects. When normal subjects bisect vertical (radial) lines using both eyes, they demonstrate a far attentional bias, misbisecting lines away from their body. In a monocular viewing experiment, we found that the majority of subjects, who were right eye dominant, had relatively nearer bisections and a diminished far bias when they used their right eye (left eye covered) compared with when they used their left eye (right eye covered). The smaller group of subjects who were left eye dominant had relatively nearer bisections and a diminished far bias when they used their left eye compared with when they used their right eye. In the hemispatial placement experiment, we directly manipulated hemispheric engagement by having subjects perform the same task in right and left hemispace. We found that right eye dominant subjects had a diminished far bias in right hemispace relative to left hemispace. Left eye dominant subjects showed the opposite pattern and had a diminished far bias in left hemispace. For both groups, spatial presentation affected performance more for the non-dominant eye. The results suggest that monocular viewing is associated with preferential activation of attentional systems in the contralateral hemisphere, and that the right hemisphere (at least in right eye dominant subjects) is biased towards far space. Finally, the results suggest that the poorly understood phenomenon of eye dominance may be related to hemispheric specialization for visual attention.
161 citations
01 Jan 2002
152 citations
TL;DR: The results indicate that the competitive interactions between a deprived and nondeprived eye evident in the primary visual cortex can co-occur with complementary interactions in extrastriate cortex that enable a relative sparing of some visual functions after early monocular deprivation.
115 citations
TL;DR: The lateralization of sensory and motor functions has been recently demonstrated in various groups of vertebrates in octopuses and there were no sex differences for visual lateralization.
92 citations
TL;DR: Evidence is provided that correlated binocular input is essential for recovery from monocular deprivation, and is a powerful demonstration of the importance of cooperative, associative mechanisms in the developing visual cortex.
Abstract: Monocular deprivation (MD) has much more rapid and severe effects on the ocular dominance of neurons in the primary visual cortex (V1) than does binocular deprivation1. This finding underlies the widely held hypothesis that the developmental plasticity of ocular dominance reflects competitive interactions for synaptic space between inputs from the two eyes2. According to this view, the relative levels of evoked activity in afferents representing the two eyes determine functional changes in response to altered visual experience. However, if the deprived eye of a monocularly deprived kitten is simply reopened, there is substantial physiological and behavioural recovery, leading to the suggestion that absolute activity levels, or some other non-competitive mechanisms, determine the degree of recovery from MD3, 4, 5, 6, 7. Here we provide evidence that correlated binocular input is essential for such recovery. Recovery is far less complete if the two eyes are misaligned after a period of MD. This is a powerful demonstration of the importance of cooperative, associative mechanisms in the developing visual cortex.
86 citations
TL;DR: The system presented in this work derives from the integration of the research work developed by the University of Parma and I.N.S.A. of Rouen, thus allowing the identification of the sole characteristics belonging to a vehicle.
Abstract: This paper presents a stereo vision system for vehicle detection. It has been conceived as the integration of two different subsystems. Initially a stereo vision based system is used to recover the most relevant 3D features in the scene; due to the algorithm's generality, all the vertical features are extracted as potentially belonging to a vehicle in front of the vision system. This list of significant patterns is fed to a second subsystem based on monocular vision; it processes the list computing a match with a general model of a vehicle based on symmetry and shape, thus allowing the identification of the sole characteristics belonging to a vehicle. The system presented in this work derives from the integration of the research work developed by the University of Parma (Italy) and I.N.S.A. of Rouen (France). The two subsystems have been integrated into the GOLD software and are currently under testing using the ARGO experimental vehicle.
86 citations
TL;DR: The 2 experiments show that whereas perception of location does not depend on whether viewing is monocular or binocular, perception of shape becomes more veridical when viewing is binocular and is not fully constrained by the perceived locations of the vertices that define the shape.
Abstract: There are often large perceptual distortions of shapes lying on the ground plane, even in well-lit environments. These distortions occur under conditions for which the perception of location i saccurate. Four hypotheses are considered for reconciling these seemingly paradoxical results, after which 2 experiments are reported that lend further support to 1 of them--that perception of shapeand perception of location are sometimes dissociable. The 2 experiments show that whereas perception of location does not depend on whether viewing is monocular or binocular (when other distance cues are abundant), perception of shape becomes more veridical when viewing is binocular. This means that perception of shape is not fully constrained by the perceived locations of the vertices that define the shape.
78 citations
TL;DR: The aim of these studies was to explore the role of binocular vision during the approach phase and step over the obstacle and the contribution of head movements to acquisition of depth information under monocular vision.
Abstract: Although the contribution of binocular vision to reach-to-grasp movements has been extensively studied, it has been largely ignored in locomotion. The aim of these studies was to explore the role of binocular vision during the approach phase and step over the obstacle and the contribution of head movements to acquisition of depth information under monocular vision. Binocular and monocular vision was manipulated in different phases using either an eye patch or liquid crystal glasses. Head movement relative to the trunk was restricted in the first experiment by a modified Ferno Universal Head Immobilizer attached to a rigid board strapped to the participant's back. Whole body kinematics were collected by placing infrared diodes on anatomical landmarks and using an Optotrak imaging system. Several measures related to head and limb movement were analyzed. Three major findings emerged from these studies. First, binocular vision is important for the acquisition of accurate information about the surrounding environment: accuracy but not precision of limb elevation over the obstacle was adversely affected when binocular vision was unavailable. Second, motion parallax due to self-motion provides the most critical depth information and it can be used to partially compensate for the loss of binocular vision. Although head movement is not essential to augment depth information, it is important for reorientation of the visual field to obtain the necessary information about the moving limbs when visual field is suddenly limited under monocular vision. Third, step over the obstacle is pre-planned based on visual information acquired during the approach phase: changes in visual condition during the adaptive step do not influence the limb trajectory. Collectively these three studies provide unique insights into the contribution of binocular vision during adaptive locomotion.
72 citations
TL;DR: It was found that observers perceived only one grid orientation when the two specified orientations were similar, but more interestingly, when the monocular--and binocular-specified orientation were rather different, observers experienced perceptual bi-stability (they were able to select either a perspective--or a disparity-dominated percept).
Abstract: We examined how much depth we perceive when viewing a depiction of a slanted plane in which binocular disparity and monocular perspective provide different slant information. We exposed observers to a grid stimulus in which the monocular--and binocular-specified grid orientations were varied independently across stimulus presentations. The grids were slanted about the vertical axis and observers estimated the slant relative to the frontal plane. We were particularly interested in the metrical aspects of perceived slant for a broad spectrum of possible combinations of disparity--and perspective-specified slants. We found that observers perceived only one grid orientation when the two specified orientations were similar. More interestingly, when the monocular--and binocular-specified orientations were rather different, observers experienced perceptual bi-stability (they were able to select either a perspective--or a disparity-dominated percept).
57 citations
TL;DR: There are many obstacles that patients face in making the transition to monocular vision, and few patients receive any formal instruction to help them adapt, yet many indicate that it would be beneficial.
Abstract: Purpose The study is conducted to determine the effect of acquired monocular vision (enucleation, phthisis) on the daily activities of patients. Methods Sixty-five patients in a case series completed a 30-question survey evaluating the functional consequences of monocular vision. Results Patients with sudden visual loss adapted more slowly than those with gradual loss (8.8 versus 3.6 months). Difficulties with depth perception and cosmesis were prevalent. Unexpected consequences included neck pain, strain with reading, employment change, depression, car accidents, and alcoholism. Ninety-one percent of patients had no formal training to help them adapt. Conclusions More than previously appreciated, there are many obstacles that patients face in making the transition to monocular vision. Few patients receive any formal instruction to help them adapt, yet many indicate that it would be beneficial.
TL;DR: The data show that the oculomotor signal in Erkelens' particular monocular condition was considerably weaker than in his binocular condition; therefore, the rarity of the monocular cyclopean illusion is not surprising.
TL;DR: In all three cases depth was considerably impaired when the monocular texture did not match either the background or the more distant surface.
TL;DR: Evidence is found that perceiveddistance is correlated with simulated distance in terms of precision and accuracy, the accuracy in the distance estimate is slightly improved by the presence of a ground-floor surface, the perceived distance is not altered significantly when the visual field size increases, and the absolute distance is estimated correctly during self-motion.
Abstract: We investigated the role of extraretinal information in the perception of absolute distance. In a computersimulated environment, monocular observers judged the distance of objects positioned at different locations in depth while performing frontoparallel movements of the head. The objects were spheres covered with random dots subtending three different visual angles. Observers viewed the objects at eye level, either in isolation or superimposed on a ground floor. The distance and size of the spheres were covaried to suppress relative size information. Hence, the main cues to distance were the motion parallax and the extraretinal signals. In three experiments, we found evidence that (1) perceived distance is correlated with simulated distance in terms of precision and accuracy, (2) the accuracy in the distance estimate is slightly improved by the presence of a ground-floor surface, (3) the perceived distance is not altered significantly when the visual field size increases, and (4) the absolute distance is estimated correctly during self-motion. Conversely, stationary subjects failed to report absolute distance when they passively observed a moving object producing the same retinal stimulation, unless they could rely on knowledge of the three-dimensional movements.
TL;DR: Predictions from monocular motion data closely match trajectory perception data, unlike those from BVD sources, which suggest that the interocular velocity differences make a significant contribution to stereomotion trajectory perception.
Abstract: Perceived stereomotion trajectory was measured before and after adaptation to lateral motion in the dominant or nondominant eye to assess the relative contributions of 2 cues: changing disparity and interocular velocity difference. Perceived speed for monocular lateral motion and perceived binocular visual direction (BVD) was also assessed. Unlike stereomotion trajectory perception, the BVD of static targets showed an ocular dominance bias, even without adaptation. Adaptation caused equivalent biases in perceived trajectory and monocular motion speed, without significantly affecting perceived BVD. Predictions from monocular motion data closely match trajectory perception data, unlike those from BVD sources. The results suggest that the interocular velocity differences make a significant contribution to stereomotion trajectory perception.
TL;DR: The results indicated that the difference of the horizontal position did not covary with their perceived relative depth, suggesting that the visual direction and perceived depth of the monocular line are mediated via different mechanisms.
TL;DR: Investigation of the change in torsional eye alignment and its relation to vertical eye alignment after eight hours of monocular occlusion revealed an excyclophoria during occlusions, which appears to be the baseline state of binocular alignment.
TL;DR: The results indicate a greater degree of binocular summation for luminance change than for color change, and this result was largely independent of the motor component of reaction time.
Abstract: We determined visual reaction times to monocular and binocular changes in the luminance of isochromatic stimuli and to monocular and binocular changes in the color of isoluminant stimuli. Two isoluminant color changes were tested: chromatic variations along the red—green axis of Boynton’s (1986) two-stage color vision model and chromatic variations along the yellow—blue axis of the same model. The results indicate a greater degree of binocular summation for luminance change than for color change. This result was largely independent of the motor component of reaction time.
TL;DR: Two-dimensional filtered noise textures are used to explore the conditions under which the visual system can piece together the monocular fragments of occluded surfaces, and the discovery of coherent surfaces under these conditions seems to reflect the operation of a high-level integration process, failures of which drive rivalry.
TL;DR: The dynamical limits for both vergence and version are imposed in the monocular visual pathways, before the inputs from the two eyes are combined.
TL;DR: In this article, the authors measured the ability to report the tilt (direction of maximal slope) of a plane under monocular viewing conditions, from static depth cues (square grid patterns) and motion parallax (small rotations of the plane about a frontoparallel axis).
TL;DR: Grip aperture and grip force are measured during prehension movements executed with binocular and monocular viewing to show that, while grip apertures increase with monocular vision, consistent with altered visuomotor safety margins, maximum grip force is nevertheless reduced, consistentWith a misperception of object size.
TL;DR: A new study has shown that neurons in the visual cortex are specialized to encode the larger range of horizontal - relative to vertical - disparities that occurs in central vision.
Journal Article•
TL;DR: Prolonged fusion of a vertical disparity is associated with a change in the orientation of Listing's plane that persists under monocular viewing, and possible mechanisms include phoria adaptation, the prolonged fusional effort itself, and the residual disparity that must be overcome by sensory mechanisms.
Abstract: PURPOSE To determine whether prolonged fusion of an imposed vertical disparity leads to a change in the orientation of Listing's plane, even when measured during monocular viewing. METHODS Four normal subjects (age range, 24-37 years) wore Fresnel prisms of increasing power for 72 hours to produce a final left-over-right disparity (range, 7-11 prism diopters [approximately 3.9 - 6.2 degrees]) that was still fusible. Eye movements were measured binocularly, using three-axis search coils, as subjects fixed on an array of light-emitting diodes (LEDs) arranged on a flat screen, 124 cm away. A regression was used to fit the data points to a plane (Listing's plane) during monocular and binocular viewing. From each planar fit, the horizontal and vertical components of primary position (the direction of gaze that is perpendicular to Listing's plane) were calculated. Baseline data were collected in the unadapted state, either just before or at least 4 days after wearing the prisms. RESULTS After the period of viewing through the prisms, there was a change in vertical phoria (prism adaptation) ranging from 1.6 to 3.3. There was a significant (P < 0.01) shift of the relative orientation of the vertical component of primary position between the two eyes of 6.3 +/- 1.7 degrees (right eye value minus left eye, up being positive, each measured during monocular viewing). There was no consistent pattern of change in the horizontal component of primary position. CONCLUSIONS Prolonged fusion of a vertical disparity is associated with a change in the orientation of Listing's plane that persists under monocular viewing. Possible mechanisms include phoria adaptation, the prolonged fusional effort itself, and the residual disparity that must be overcome by sensory mechanisms.
TL;DR: It is found that following monocular retinal lesions, deprived neurons in cat area 17 can acquire new receptive fields if the lesion occurred relatively early in life and the lesioned cats experienced a substantial period of recovery (>3 years).
Abstract: Neither discrete peripheral retinal lesions nor the normal optic disk produces obvious holes in one's percept of the world because the visual brain appears to perceptually "fill in" these blind spots. Where in the visual brain or how this filling in occurs is not well understood. A prevailing hypothesis states that topographic map of visual cortex reorganizes after retinal lesions, which "sews up" the hole in the topographic map representing the deprived area of cortex (cortical scotoma) and may lead to perceptual filling in. Since the map reorganization does not typically occur unless retinotopically matched lesions are made in both eyes, we investigated the conditions in which monocular retinal lesions can induce comparable map reorganization. We found that following monocular retinal lesions, deprived neurons in cat area 17 can acquire new receptive fields if the lesion occurred relatively early in life (8 weeks of age) and the lesioned cats experienced a substantial period of recovery (>3 years). Quantitative determination of the monocular and binocular response properties of reactivated units indicated that responses to the lesioned eye for such neurons were remarkably robust, and that the receptive-field properties for the two eyes were generally similar. Moreover, excitatory or inhibitory binocular interactions were found in the majority of experimental units when the two eyes were activated together. These results are consistent with the hypothesis that map reorganization after monocular retinal lesions require experience-dependent plasticity and may be involved in the perceptual filling in of blind spots due to retinal lesions early in life.
Journal Article•
TL;DR: In this paper, a model that uses binocular visual input to detect landmarks and estimate their distance based on disparity between the two images is presented, where feature detectors provide input to saliency maps that find landmarks as combinations of features.
Abstract: We present a model that uses binocular visual input to detect landmarks and estimates their distance based on disparity between the two images. Feature detectors provide input to saliency maps that find landmarks as combinations of features. Interactions between feature detectors for the left and right images and between the saliency maps enables corresponding landmarks to be found. We test the model in the real world and show that it reliably detects landmarks and estimates their distances.
TL;DR: The results of the present study further question the view that binocular vision is pre-eminent in the control of natural prehensile movements.
Abstract: Recent evidence suggests that the visual control of prehension may be less dependent on binocular information than has previously been thought. Studies investigating this question, however, have generally only examined reaches to single objects presented in isolation, even though natural prehensile movements are typically directed at objects in cluttered scenes which contain many objects. The present study was designed, therefore, to assess the contribution of binocular information to the control of prehensile movements in multiple-object scenes. Subjects reached for and grasped objects presented either in isolation or in the presence of one, two or four additional 'flanking' objects, under binocular and monocular viewing conditions. So that the role of binocular information could be clearly determined, subjects made reaches both in the absence of a visible scene around the target objects (self-illuminated objects presented in the dark) and under normal ambient lighting conditions. Analysis of kinematic parameters indicated that the removal of binocular information did not significantly affect many of the major indices of the transport component, including peak wrist velocity. However, peak grip apertures increased and subjects spent more time in the final slow phase of movement, prior to grasping the object, during monocularly guided reaches. The dissociation between effects of binocular versus monocular viewing on transport and grasp parameters was observed irrespective of the presence of flanking objects. These results therefore further question the view that binocular vision is pre-eminent in the control of natural prehensile movements.
Journal Article•
TL;DR: The model based binocular stereo method inoculates the model based monocular vision and advanced least square method to realize the model restriction, and the compare analysis between the two methods and the experiment result will be given.
Abstract: The related pose between two space objects can be determined if the coordinates of a group marks at two reference frames are measured. The precondition of the above method is that the site relationship among the marks must be changeless at the two reference frames, but this relationship will be destroyed by the computational error. So two model based visual methods include model based monocular vision method and model based binocular stereo method are introduced. The model based monocular vision method starts with the physical meaning of vision, and get the 3D space coordinates of marks by simple restrictive iterative. The model based binocular stereo method inoculates the model based monocular vision and advanced least square method to realize the model restriction. The compare analysis between the two methods and the experiment result will be given at last. Using these method, the model based monocular vision can reach very high measurement precise, and the model based binocular stereo has a little higher measure than the model based monocular vision. For any method, the size of quantization error will effect the measurement precise of visual method directly. These method has been used in mobile robot visual guided experiment at our laboratory successfully, the speed of image grabbing is 0 3 second per frame.
28 Aug 2002
TL;DR: This work presents a model that uses binocular visual input to detect landmarks and estimates their distance based on disparity between the two images and test the model in the real world and show that it reliably detects landmarks and estimated their distances.
Abstract: We present a model that uses binocular visual input to detect landmarks and estimates their distance based on disparity between the two images. Feature detectors provide input to saliency maps that find landmarks as combinations of features. Interactions between feature detectors for the left and right images and between the saliency maps enables corresponding landmarks to be found. We test the model in the real world and show that it reliably detects landmarks and estimates their distances.
10 Dec 2002
TL;DR: It is shown that the two corresponding modules - laser GVG construction and visual landmarks learning and recognition - can cooperate to complete each other, as image processing can be enhanced by some structural knowledge about the scene, whereas the GVG is annotated, even as far as its edges are concerned, by qualitative visual information.
Abstract: This article describes the integration in a complete navigation system of an environment modeling method based on a Generalized Voronoi Graph (GVG), relying on laser data, on the one hand, and of a localization method based on monocular vision landmark learning and recognition framework, on the other hand. Such a system is intended to work in structured environments. It is shown that the two corresponding modules - laser GVG construction and visual landmarks learning and recognition - can cooperate to complete each other, as image processing can be enhanced by some structural knowledge about the scene, whereas the GVG is annotated, even as far as its edges are concerned, by qualitative visual information.