Binocular single vision and perceptual processing.

Stimuli with small binocular disparities are seen as single, despite their differing visual directions for the two eyes. Such stimuli also yield stereopsis, but stereopsis and single vision can be dissociated. The occurrence of binocular single vision depends not only on the disparities of individual stimulus elements, but also on the geometrical relation of different parts of the pattern presented to each eye. A pair of vertical bars with opposite binocular disparities is seen as single if the pair is moderately widely spaced but not if it is narrow. Vertical alignment and identity in length of such bars also increase the occurrence of double vision. It is argued that these effects reflect the extraction of features of the monocular patterns, with these detected monocular features determining the binocular percept. Single and double vision of bars differing in orientation can be similarly analysed. The occurrence of relatively elaborate processing of monocular signals does not exclude the possibility that binocular interaction can occur between signals that have not been so processed. Multiple sites or types of binocular interaction are likely.     

Impact of binocular vision impairments on reading skills in first-year schoolchildren with high visual acuity

The aim of this study was to investigate the state of binocular vision in first-year schoolchildren with high binocular visual acuity. The results have shown that only 5.1% of these children had normal binocular vision, whereas 25.7% of them had moderate impairments, and 67.9% had severe plus moderate impairments in binocular vision. Significant intergroup differences between schoolchildren with learning difficulties in reading and children with normal reading have been detected in the mean indicators for the distance of near-point of convergence (p < 0.001) and the visual behavior symptoms that confirmed binocular dysfunctions (p < 0.002).     

Quality of Visual Cue Affects Visual Reweighting in Quiet Standing

Sensory reweighting is a characteristic of postural control functioning adopted to accommodate environmental changes. The use of mono or binocular cues induces visual reduction/increment of moving room influences on postural sway, suggesting a visual reweighting due to the quality of available sensory cues. Because in our previous study visual conditions were set before each trial, participants could adjust the weight of the different sensory systems in an anticipatory manner based upon the reduction in quality of the visual information. Nevertheless, in daily situations this adjustment is a dynamical process and occurs during ongoing movement. The purpose of this study was to examine the effect of visual transitions in the coupling between visual information and body sway in two different distances from the front wall of a moving room. Eleven young adults stood upright inside of a moving room in two distances (75 and 150 cm) wearing a liquid crystal lenses goggles, which allow individual lenses transition from opaque to transparent and vice-versa. Participants stood still during five minutes for each trial and the lenses status changed every one minute (no vision to binocular vision, no vision to monocular vision, binocular vision to monocular vision, and vice-versa). Results showed that farther distance and monocular vision reduced the effect of visual manipulation on postural sway. The effect of visual transition was condition dependent, with a stronger effect when transitions involved binocular vision than monocular vision. Based upon these results, we conclude that the increased distance from the front wall of the room reduced the effect of visual manipulation on postural sway and that sensory reweighting is stimulus quality dependent, with binocular vision producing a much stronger down/up-weighting than monocular vision.     

Plasticity of monocular and binocular vision following cerebral blindness: evoked potential evidence

Using monocular and dynamic random dot correlogram (DRDC) stimuli, sequential visual evoked potentials changes were demonstrated in 2 patients following cerebral blindness. The recovery of binocular vision was delayed in comparison to the recovery of monocular vision. The results are not due to simple acuity impairment or convergence deficiency, and thus provide evidence for the vulnerability of postsynaptic cortical mechanisms of human binocular vision.     

Monocular vision leads to a dissociation between grip force and grip aperture scaling during reach-to-grasp movements

It has been argued that visual perception and the visual control of action depend upon functionally distinct and anatomically separable brain systems. Electrophysiological evidence indicates that binocular vision may be particularly important for the visuomotor processing within the posterior parietal cortex, and neuropsychological and psychophysical studies confirm that binocular vision is crucial for the accurate planning and control of prehension movements. An unresolved issue concerns the consequences for visuomotor processing of removing binocular vision. By one account, monocular viewing leads to reliance upon pictorial visual cues to calibrate grasping and results in disruption to normal size-constancy mechanisms. This proposal is based on the finding that maximum grip apertures are reduced with monocular vision. By a second account, monocular viewing results in the loss of binocular visual cues and leads to strategic changes in visuomotor processing by way of altered safety margins. This proposal is based on the finding that maximum grip apertures are increased with monocular vision. We measured both grip aperture and grip force during prehension movements executed with binocular and monocular viewing. We demonstrate that each of the above accounts may be correct and can be observed within the same task. Specifically, we show that, while grip apertures increase with monocular vision, consistent with altered visuomotor safety margins, maximum grip force is nevertheless reduced, consistent with a misperception of object size. These results are related to differences in visual processing required for calibrating grip aperture and grip force during reaching.     

The effects of vision on the general locomotor behaviour of the goldfish, Carassius auratus

Comparison of the locomotor behaviour of normal, unilaterally and bilaterally blinded goldfish (Carassius auratus) demonstrated the roles of perspective vision (depth perception), which requires binocular vision, and of vision provided by only one eye, in the control of locomotion. Because normal and bilaterally blinded fish exhibited similar size and direction of angles of turn, a similar number of consecutive turns in the same direction and the same turning frequency, normal, binocular vision plays no role in the control of turning behaviour. Unilaterally blinded fish exhibited a strong bias in turning behaviour which resulted in their displaying circus movements toward the blinded side, a direction opposite to that reported by others for both invertebrates and vertebrates with unilateral sensory elimination. The mean step length was significantly increased by both uni- and bilateral blinding, and its temporal relationship with turning frequency and distance swum was also changed. Perspective vision (binocular) therefore controls these parameters. The significantly lower velocity of bilaterally blinded fish and the similarity between the other two test groups, indicated that sight by one eye only was sufficient to mediate velocity control.     

Ideal Binocular Disparity Detectors Learned Using Independent Subspace Analysis on Binocular Natural Image Pairs

An influential theory of mammalian vision, known as the efficient coding hypothesis, holds that early stages in the visual cortex attempts to form an efficient coding of ecologically valid stimuli. Although numerous authors have successfully modelled some aspects of early vision mathematically, closer inspection has found substantial discrepancies between the predictions of some of these models and observations of neurons in the visual cortex. In particular analysis of linear-non-linear models of simple-cells using Independent Component Analysis has found a strong bias towards features on the horoptor. In order to investigate the link between the information content of binocular images, mathematical models of complex cells and physiological recordings, we applied Independent Subspace Analysis to binocular image patches in order to learn a set of complex-cell-like models. We found that these complex-cell-like models exhibited a wide range of binocular disparity-discriminability, although only a minority exhibited high binocular discrimination scores. However, in common with the linear-non-linear model case we found that feature detection was limited to the horoptor suggesting that current mathematical models are limited in their ability to explain the functionality of the visual cortex.     

Protein synthesis-independent plasticity mediates rapid and precise recovery of deprived eye responses

Monocular deprivation (MD) for a few days during a critical period of development leads to loss of cortical responses to stimulation of the deprived eye. Despite the profound effects of MD on cortical function, optical imaging of intrinsic signals and single-unit recordings revealed that deprived eye responses and orientation selectivity recovered a few hours after restoration of normal binocular vision. Moreover, recovery of deprived eye responses was not dependent upon mRNA translation, but required cortical activity. Interestingly, this fast recovery and protein synthesis independence was restricted to the hemisphere contralateral to the previously deprived eye. Collectively, these results implicate a relatively simple mechanistic process in the reactivation of a latent set of connections following restoration of binocular vision and provide new insight into how recovery of cortical function can rapidly occur in response to changes in sensory experience.     

Fixation-sensitive areas in the eyes of the walking fly,Calliphora erythrocephala

In Calliphora erythrocephala the visual fixation behaviour in one-eyed flies and partial blinded flies has been investigated. One-eyed flies show approximately the same stripe and edge fixation response as intact flies. Elimination of the frontal eye parts including the binocular field of vision does not effect the visual stripe fixation. On the other hand, if only the frontal areas of both eyes including the binocular field of vision are left open, no preferential direction can be observed (Fig. 1–3). The results imply the existence of a fixation-sensitive area of the eye located outside the binocular field of vision.     

Acuity and hyperacuity for pupils of 11-17 years old

Estimations of hyperacuity and visual acuity (VA) have been compared in schoolchildren aged 11-17 years with normal vision. VA was measured using Landolt Cs and Tumbling Es. Hyperacuity was measured by vernier stimuli. Acuity estimations depended on the test stimuli. They were in 1.1 times over for Landolt Cs than for Tumbling Es. Hyperacuity estimations exceeded VA in 1.25-4.1 times. They were almost twice as high among pupils of 16 years compared to 13-year-olds, in contrast to estimates of VA, which practically did not change with age. Binocular VA was significantly higher monocular VA in 1.05 times regardless of age. The ratio between the binocular and monocular hyperacuity estimates for thirteen years pupils in average was equal to 1.9, while for sixteen years pupils--1.2. We discuss the contribution of binocular vision in the development of mechanisms of VA and hyperacuity in ontogenesis and the difference between these mechanisms.     

Seeing rainbows

Mammals generally have colour vision inferior to that of other vertebrates. This is partially redressed in primates, but the underlying mechanisms differ in Old World and New World primate groups. How has this occurred and what were the key events in the molecular evolution of primate colour vision?     

正常及异常双眼视觉的视动震颤（OKN）反应特性研究

为探讨不同双眼视觉状态下ＯＫＮ反应的特性,对正常人和不同类型的双眼视觉异常者的单眼鼻向及颞向ＯＫＮ反应进行了研究。实验发现：单眼视觉抑制者表现出鼻向与颞向ＯＫＮ反应不对称特性;两眼皆因视剥夺造成双眼视觉异常者主要以ＯＫＮ眼动增益降低为特点;双眼视觉正常者鼻、颞向ＯＫＮ反应是对称的。结果表明：单眼ＯＫＮ眼动反应的不对称特性及增益改变对探讨双眼视觉异常机制有重要意义,为视皮层双眼细胞异常导致单眼ＯＫＮ不对称的假设提供了支持性证据,并对弱视早期诊断及其分类有重要价值。     

Reorganization of callosal interhemispheric connections in the adult cat: effects of monocular occlusion after chiasmotomy

Two groups of adult cats were chiasmotomized and their cortical receptive fields (17-18 boundary) were compared after a postoperative period of ca 6 weeks. In one group, binocular vision was maintained during that period, in the other one, one eye was sutured at the time of the chiasmotomy, depriving one hemisphere from patterned vision through the direct pathway. In monocular chiasmotomized animals, the receptive fields to stimulation of the contralateral eye were significantly larger than in the binocular ones.     

On the evidence for a 'pure' binocular process in human vision

Wolfe (1986, Psychol. Rev. 93, 269-282) proposed a model of human binocular vision based on the assumption of two functionally distinct classes of binocular neuron. These neurons may be regarded as logical AND and OR gates. In the present paper we assess the evidence relevant to this assumption. We find that while both types of binocular neuron have been described in the cortex of cat and monkey, there is no indication that they form functionally separate populations. Critical analysis of the psychophysical evidence for AND and OR channels in human vision suggests that much of the data presented in favor of an AND channel is subject to alternative interpretations. We conclude that the available data are not consistent with the existence of separate channels as proposed by Wolfe.     

Variations in primate color vision: Mechanisms and utility

Among mammals, only the primates have acquired the biological machinery needed for highly acute color vision. That distinction led Gordon Walls, perhaps the foremost authority on comparative vision of this century, to suggest long ago that “the color vision of the higher primates is assuredly a law unto itself, genetically and historically speaking.”¹ Primate color vision is indeed unique. One manifestation of this uniqueness is that color vision abilities vary significantly, not only between some groupings of primate species, but, remarkably, among individuals of a considerable number of species. Although the functional significance of these variations remains, in large measure, to be sorted out, the past decade has brought much progress in revealing the mechanisms that underlie variation.     

Stereoscopic vision: solving the correspondence problem

Neurons in early visual areas respond to horizontal disparity in images that do not give rise to stereopsis. False binocular matches, however, are discarded at the apex of the visual pathway: the activity of neurons in the primate inferior temporal cortex correlates directly with conscious depth perception.     

Stereopsis and the random element in the organization of the striate cortex.

Receptive field position and orientation disparities are both properties of binocularly discharged striate neurons. Receptive field position desparities have been used as a key element in the neural theory for binocular depth discrimination. Since most striate cells in the cat are binocular, these position disparities require that cells immediately adjacent to one another in the cortex should show a random scatter in their monocular receptive field positions. Superimposed on the progressive topographical representation of the visual field on the striate cortex there is experimental evidence for a localized monocular receptive field position scatter. The suggestion is examined that the binocular position disparities are built up out of the two monocular position scatters. An examination of receptive field orientation disparities and their relation to the random variation in the monocular preferred orientations of immediately adjacent striate neurons also leads to the conclusion that binocular orientation disparities are a consequence of the two monocular scatters. As for receptive field position, the local scatter in preferred orientation is superimposed on a progressive representation of orientation over larger areas of the cortex. The representation in the striate cortex of visual field position and of stimulus orientation is examined in relation to the correlation between the disparities in receptive field position and preferred orientation. The role of orientation disparities in binocular vision is reviewed.     

Computational studies of the extraction of visual spatial information from binocular and motion cues

This paper reviews some of the contributions that work in computational vision has made to the study of biological vision systems. We concentrate on two areas where there has been strong interaction between computational and experimental studies: the use of binocular stereo to recover the distances to surfaces in space, and the recovery of the three-dimensional shape of objects from relative motion in the image. With regard to stereo, we consider models proposed for solving the stereo correspondence problem, focussing on the way in which physical properties of the world constrain possible methods of solution. We also show how critical observations regarding human stereo vision have helped to shape these models. With regard to the recovery of structure from motion, we focus on how the constraint of object rigidity has been used in computational models of this process.     

Arm movements in monkeys: behavior and neurophysiology

Reaching to objects of interest is very common in the behavioral repertoire of primates. Monkeys possess keen binocular vision and make graceful and accurate arm movements. This review focuses on behavioral and neurophysiological aspects of eye-hand coordination in behaving monkeys, including neural coding mechanisms at the single cell level and in neuronal populations. The results of these studies have converged to a common behavioral-neurophysiological ground and provided a springboard for studies of brain mechanisms underlying motor cognitive function.     

双眼倾斜效应中频率和相对距离乘积的恒常性

双眼协同的功能不仅是扩大视野,而且更为重要的是人和动物获得对环境特有的立体感觉。但立体视觉信息处理机制至今尚不清楚,有待深入研究。 本文利用自己研制的一种多功能立体图形发生器产生的亮度以正弦波调制的光栅条纹作为刺激图形,设计并做了一系列有关频差倾斜现象;其次,分别对不同中心频率和不同观察距离下,左、右刺激器处于与被试者不同距离下频差倾斜观象中的频差与倾斜度的关系进行了研究。结果表明,对于频率差分析存在着频率和相对远近乘积的恒常性,这是判断物体精细凸凹的一种global stereopsis性质的心理规律。