Overlap Of Visual Fields Research Articles

A Fish-like Binocular Vision System for Underwater Perception of Robotic Fish.

Biological fish exhibit a remarkably broad-spectrum visual perception capability. Inspired by the eye arrangement of biological fish, we design a fish-like binocular vision system, thereby endowing underwater bionic robots with an exceptionally broad visual perception capacity. Firstly, based on the design principles of binocular visual field overlap and tangency to streamlined shapes, a fish-like vision system is developed for underwater robots, enabling wide-field underwater perception without a waterproof cover. Secondly, addressing the significant distortion and parallax of the vision system, a visual field stitching algorithm is proposed to merge the binocular fields of view and obtain a complete perception image. Thirdly, an orientation alignment method is proposed that draws scales for yaw and pitch angles in the stitched images to provide a reference for the orientation of objects of interest within the field of view. Finally, underwater experiments evaluate the perception capabilities of the fish-like vision system, confirming the effectiveness of the visual field stitching algorithm and the orientation alignment method. The results show that the constructed vision system, when used underwater, achieves a horizontal field of view of 306.56°. The conducted work advances the visual perception capabilities of underwater robots and presents a novel approach to and insight for fish-inspired visual systems.

Visual field inhomogeneous in brain–computer interfaces based on rapid serial visual presentation

Objective. Visual attention is not homogeneous across the visual field, while how to mine the effective electroencephalogram (EEG) characteristics that are sensitive to the inhomogeneous of visual attention and further explore applications such as the performance of brain–computer interface (BCI) are still distressing explorative scientists. Approach. Images were encoded into a rapid serial visual presentation (RSVP) paradigm, and were presented in three visuospatial patterns (central, left/right, upper/lower) at the stimulation frequencies of 10, 15 and 20 Hz. The comparisons among different visual fields were conducted in the dimensions of subjective behavioral and EEG characteristics. Furthermore, the effective features (e.g. steady-state visual evoked potential (SSVEP), N2-posterior-contralateral (N2pc) and P300) that sensitive to visual-field asymmetry were also explored. Main results. The visual fields had significant influences on the performance of RSVP target detection, in which the performance of central was better than that of peripheral visual field, the performance of horizontal meridian was better than that of vertical meridian, the performance of left visual field was better than that of right visual field, and the performance of upper visual field was better than that of lower visual field. Furthermore, stimuli of different visual fields had significant effects on the spatial distributions of EEG, in which N2pc and P300 showed left–right asymmetry in occipital and frontal regions, respectively. In addition, the evidences of SSVEP characteristics indicated that there was obvious overlap of visual fields on the horizontal meridian, but not on the vertical meridian. Significance. The conclusions of this study provide insights into the relationship between visual field inhomogeneous and EEG characteristics. In addition, this study has the potential to achieve precise positioning of the target’s spatial orientation in RSVP-BCIs.

Hemifield slide from traumatic optic chiasmopathy

A 56-year-old man suffered a high velocity linear acceleration closed head injury, resulting in skull fractures including bone dehiscence at the planum sphenoidale and tuberculum sellae. After regaining consciousness, he reported blurry vision and episodic diplopia. Visual field testing showed a bitemporal hemianopia. Ocular motility testing uncovered no misalignment. Brain MRI revealed post-traumatic encephalomalacia within the optic chiasm, resulting in the visual field defect and subsequent hemifield slide. Normally, cerebral processing of overlap between the visual fields prevents hemifield slide, which is caused by episodic loss of visual field overlap with subsequent slipping or sliding apart of images.

Retinogeniculostriate Pathway Components Scale with Orbit Convergence Only in Primates and Not in Other Mammals

Studies of the relative sizes of brain components in mammals suggest that areas responsible for sensory processing, including visual processing, are correlated with aspects of ecology, especially activity pattern. Some studies suggest that primate orbit convergence and binocular vision are correlated with the overall size of the brain as well as components of the visual pathway, such as the lateral geniculate nucleus. However, the question remains whether components of the visual pathway are correlated with orbit convergence and binocular visual field overlap in nonprimate mammals. Here, we examine the relationship between orbit convergence and the volumes of components of the visual pathway (optic tract, dorsal lateral geniculate nucleus and primary visual cortex). Data on orbit orientation are combined with those on overall brain volume as well as brain component volumes in a taxonomically diverse sample of mammals. Our results demonstrate that nonprimate mammals scale isometrically for component volumes along the visual pathway, whereas primates display negatively allometric relationships. However, only among primates is higher orbit convergence correlated with volumetrically larger lateral geniculate nuclei and visual cortices. Diurnal primates exhibit statistically larger visual pathway components when compared to nocturnal primates. Nonprimate mammals do not display activity pattern differences with the single exception of optic tract sizes. We conclude that binocular vision was a much stronger factor in the evolution of the visual system in primates than in other mammals.

A theoretical model of shoaling behavior based on a consideration of patterns of overlap among the visual fields of individual members

We propose a hypothetical visual field overlap (VFO) model for shoaling behavior. While solitary individuals have the disadvantage of a substantial blind zone to their rear, the overlapping visual fields among shoal members allows the shoal to collectively view nearly 360°. A highly polarized shoal (i.e., a school) would be less advantageous than randomly oriented shoals because a substantial area blind to all school members (common blind zone) would occur at some distance behind the school. However, in situations where fishes must orient in one direction, the visual fields of individuals in the school overlap such that the common blind zone is considerably farther behind than the blind zone of any particular fish. A simple geometric relationship between school width, the blind angle, and the distance to the common blind zone predicts that larger schools can detect predators at a greater distance than smaller schools. Additionally, the model provides a novel explanation for the nearly universally observed tendency for fish to school together with like-sized individuals. Finally, the effect of school shape on the visual field overlap pattern would have a strong impact on predator–prey interactions. However, our model does not directly take into account the range of visibility or social interaction affects and applies only to small groups. The VFO model suggests that schooling may have arisen as an adaptation to enhance feeding efficiency by reducing the need for individual vigilant behavior while oriented into the current for feeding. We believe the VFO model promises to provide insight into the behavioral ecology of shoaling fishes and that it is highly amenable to both field and laboratory testing.

Ecomorphology of Orbit Orientation and the Adaptive Significance of Binocular Vision in Primates and Other Mammals

Primates are characterized by forward-facing, or convergent, orbits and associated binocular field overlap. Hypotheses explaining the adaptive significance of these traits often relate to ecological factors, such as arboreality, nocturnal visual predation, or saltatory locomotion in a complex nocturnal, arboreal environment. This study re-examines the ecological factors that are associated with high orbit convergence in mammals. Orbit orientation data were collected for 321 extant taxa from sixteen orders of metatherian (marsupial) and eutherian mammals. These taxa were coded for activity pattern, degree of faunivory, and substrate preference. Results demonstrate that nocturnal and cathemeral mammals have significantly more convergent orbits than diurnal taxa, both within and across orders. Faunivorous eutherians (both nocturnal and diurnal) have higher mean orbit convergence than opportunistically foraging or non-faunivorous taxa. However, substrate preference is not associated with higher orbit convergence and, by extension, greater binocular visual field overlap. These results are consistent with the hypothesis that mammalian predators evolved higher orbit convergence, binocular vision, and stereopsis to counter camouflage in prey inhabiting a nocturnal environment. Strepsirhine primates have a range of orbit convergence values similar to nocturnal or cathemeral predatory non-primate mammals. These data are entirely consistent with the nocturnal visual predation hypothesis of primate origins.

Integrating Fossil and Extant Data on the Evolution of Primate and Non‐Primate Mammal Orbit Orientation

Orbit orientation is important for visual field construction in mammals. It is hypothesized that orbit convergence and binocular visual field overlap are part of an innovative character complex that is linked to the adaptive origin of primates. Tests of this hypothesis have relied on orbit orientation and ecological data from extant mammals. However, a thorough investigation of primate orbit orientation requires the integration of extant and fossil data to reconstruct the sequence of transformations that led to the evolution of the primate circumorbital morphotype. This study combines orbit orientation data on extant and fossil taxa with methods of phylogenetic character reconstruction to analyze the sequence of orbit orientation evolution in primates and other euarchontans. Extant taxa include primates, scandentians, and dermopterans. Fossils examined here include several omomyiform, adapiform, and early anthropoid taxa as well as several plesiadapiformes, a possible outgroup to primates. Results demonstrate that alternate cladistic tree topologies lead to different reconstructed sequences of orbit evolution. If plesiadapiformes are the outgroup to primates, then several reversals or reductions in orbit convergence relative to other archontans occurred prior to the origin of primates. However, under any advocated phylogeny, some reversals must have occurred. Support: Leakey Foundation

Foraging behaviour of the slender loris ( Loris lydekkerianus lydekkerianus): implications for theories of primate origins

Members of the Order Primates are characterised by a wide overlap of visual fields or optic convergence. It has been proposed that exploitation of either insects or angiosperm products in the terminal branches of trees, and the corresponding complex, three-dimensional environment associated with these foraging strategies, account for visual convergence. Although slender lorises ( Loris sp.) are the most visually convergent of all the primates, very little is known about their feeding ecology. This study, carried out over 10 ½ months in South India, examines the feeding behaviour of L. lydekkerianus lydekkerianus in relation to hypotheses regarding visual predation of insects. Of 1238 feeding observations, 96% were of animal prey. Lorises showed an equal and overwhelming preference for terminal and middle branch feeding, using the undergrowth and trunk rarely. The type of prey caught on terminal branches (Lepidoptera, Odonata, Homoptera) differed significantly from those caught on middle branches (Hymenoptera, Coleoptera). A two-handed catch accompanied by bipedal postures was used almost exclusively on terminal branches where mobile prey was caught, whereas the more common capture technique of one-handed grab was used more often on sturdy middle branches to obtain slow moving prey. Although prey was detected with senses other than vision, vision was the key sense used upon the final strike. This study strongly supports the notion that hunting for animal prey was a key ecological determinant in selecting for visual convergence early on in primate evolution. The extreme specialisations of slender lorises, however, suggest that early primates were not dedicated faunivores and lend further support to the emerging view that both insects and fruits were probably important components of the diet of basal primates, and that exploitation of fruits may account for other key primate traits.

Morphology of the compound eye of the giant deep-sea isopod Bathynomus giganteus.

The structural organization of the compound eye of the largest known isopod, Bathynomus giganteus, is described from four specimens maintained in the laboratory for as long as two months. Living specimens have not previously been available for study. The two triangular compound eyes measure about 18 mm on the dorsal edge and are separated by an interocular distance of 25 mm. They face forward and slightly downward and may have significant overlap in visual fields. Each eye contains about 3,500 ommatidia in animals of body lengths from 22.5 cm to 37.5 cm. The packing of ommatidia is not uniform across the retina, but is nearly hexagonal in the dorsal central region and nearly square in the ventral and lateral periphery. The dioptric elements in each ommatidium consist of a laminar cornea, which is flat externally and convex internally, and a bipartite crystalline cone. Sometimes seven and sometimes eight retinular cells closely appose the proximal tip of the cone and bear the microvilli of the rhabdom. Proximal to the rhabdom the retinular cells form thin pillars near the periphery of the ommatidium, and the central portion along the optic axis at this level is occupied by interstitial cells that contain massive arrays of clear vesicles thought to serve as reflective elements. The arhabdomeral segments of the retinular cells and the interstitial cells rest on a basement membrane. Within each ommatidium the basement membrane has two extensions with cylindrical cores and thin sheets of dense material and collagen-like filaments. These sheets occupy spaces between adjacent interstitial cells up to the level of the rhabdomeral segments of the retinular cells. Arrays of pigment cells with relatively weak light-screening properties separate adjacent ommatidia. Animals were fixed both in light within a week of being brought from depth into daylight, and after 2 months of maintenance in constant darkness following such daylight exposure. In both cases, microvilli of the rhabdom were severely disrupted and the retinular cytoplasm contained numerous multivesicular bodies. Exposure to natural daylight appears to cause irreversible structural damage to the photoreceptors of these animals.

Superposition and scattering of visual fields in a compound, double eye—II. Stimulation sequences for different distances in a stomatopod from a bright habitat

1. 1. The inputs deriving from a point light moving in front of a column of ommatidia are plotted by a computer. 2. 2. Overlap of visual fields causes one main, central maximum surrounded by smaller maxima intercalated by minima. 3. 3. With increasing distance of the point from the eye the central maximum increases. 4. 4. Ommatidia in each half of the eye are stimulated sequentially in two groups. Stimulation sequences are parallel between the two halves of the eye. 5. 5. We postulate an integrative mechanism for processing the succession of simultaneous inputs and hypothesize that the animal derives information about speed and distance from that mechanism.

Possible monocular range-finding mechanisms in stomatopods from different environmental light conditions

1. 1. Stomatopods have double eyes. 2. 2. In the middle band dividing the two halves of the eye ommatidia are perpendicular to the cornea. 3. 3. Rows of ommatidia parallel to the middle band have divergent optical axes. 4. 4. In the columns across the middle band the optical axes of ommatidia near the middle band are convergent between the two halves of the eye. 5. 5. From the fifth to tenth ommatidium towards the sides optical axes on each side are parallel to each other and to those in the middle band. 6. 6. This results in a strong overlap of visual fields between ommatidia with parallel optical axes in each half of the eye and with the fields of the skewed ommatidia from the opposite half of the eye. 7. 7. We postulate this as the morphological basis for a range-finding and motion measuring device along the columns, repeated around the eye along the rows. 8. 8. We hypothesize that this device may measure distances by the amount and pattern of overlap of visual fields at each point in space. 9. 9. Species from bright light habitats show less skewed ommatidia and similar patterns of overlap are shifted to longer distances than in dim light species.

Visual orienting deficits in frogs with various unilateral lesions

We have studied the visual prey acquisition behavior of frogs with unilateral optic nerve section, unilateral tectal lobe ablation, and unilateral transverse hemisection at a level between the tectum and the cerebellum. The first two groups of animals oriented normally to stimuli throughout the region of visual field overlap and failed to respond to more peripheral stimuli on one side. Hemisected animals responded to stimuli at all positions in the visual field. For stimuli located contralateral to the lesion, the frogs oriented normally. For ipsilateral stimuli, the frogs oriented forward.

Orienting behavior of juvenile frogs with both a pre-metamorphically rotated and a normal eye

We have studied the orienting behavior of juvenile Rana pipiens in which one eye was rotated at late larval stages and the other eye left intact. Such frogs orient accurately to stimuli falling solely in the visual field of the intact eye and systematically misorient to stimuli falling solely in the field of the rotated eye. Stimuli within the area of visual field overlap elicited two distinct sets of responses, one attributable to the normal and the other to the rotated eye.

The potential binocular field and its tectal representation in Rana pipiens.

We have studied binocularity in Rana pipiens using optical, behavioral, and electrophysiological assays. The first two assays yielded a consistent picture of the size and shape of the area of uniocular visual field overlap, the potential binocular field. Potential binocular field has an extent of about 90 degrees on the horizontal in front of the frog, narrows to about 60 degrees above the frog's head, and continues to a point well behind the frog. This differs somewhat from a previous report (Fite, '73). Uniocular visual field extent on the horizontal is in excess of 225 degrees, permitting both a large binocular field and panoramic vision. The electrophysiological assay confirms the large uniocular visual field extent. It further shows that physiological binocularity closely reflects uniocular visual field overlap, in the sense that tectal loci representing positions in the potential binocular field, including those behind the frog's head, display convergent inputs from the two eyes.

The eyes of mesopelagic crustaceans

In Streetsia challengeri left and right eyes have fused and become a single cylindrical photoreceptor, which occupies the basal half of a forward directed head projection. This unusual compound eye consists of approximately 2500 ommatidia, which are arranged in such a way that the animal has almost circumferential vision, but cannot look ahead or behind. It is thought that the eye operates on light-guide principles, and that the crystalline cones are the major dioptric component. Ommatidia in anterior-posterior rows show a greater overlap of visual fields than dorso-ventrally arranged ommatidia. Cone layer and retinula are separated by a 4 micrometer thick screen-membrane, which contains tiny pigment granules of 0.15 micrometer diameter. Cells of unknown function and origin, containing unusual multitubular organelles, are regularly found near the proximal ends of the crystalline cone threads. The twisted rhabdoms measure 18--20 micrometer in diameter, and consist of microvilli 0.05 micrometer in width, which belong to five retinula cells and which show no trace of disintegration. The position of interommatidial screening pigment, the density of retinula cell vesicles and inclusions, and the narrowness of the perirhabdomal space all suggest that the eyes have been light-adapted at the time of fixation for electron microscopy. The retinula cell nuclei lie on the proximal side of the heavily pigmented basement membrane. A tapetum or basal retinula cells are not developed. It is concluded that the eye optimally combines acuity with sensitivity, and that for distance estimation parallax may be important.

Theoretical Effect of Schooling by Planktivorous Fish Predators on Rate of Prey Consumption

Effect of schooling on the rate of prey consumption by planktivorous fish is deduced by extending the Holling disk equation (i.e. the rate of prey consumption by solitary feeding fishes can be expressed by the Holling disk equation) to account for lateral visual-field overlap and reduction of prey density due to removal of prey by forward-occurring members of the school. Effect of schooling is expressed as the rate of prey consumption per member of the school relative to that by a solitary individual. This study suggests that schooling of predators occurs at the expense of prey consumption. Cost of schooling is reduced if prey densities are high, if distance between members is high, or if school size is small. There may be some advantage to schooling when prey have a clumped distribution.

The anatomic and physiological visual field of ommatidia in the complex eye of Musca

The sensitivity distribution of visual elements in the front region of the compound eye of Musca is investigated by means of intracellular micropipette recording. This distribution approximates a Gauss-function of 7.7 degree half-value in the horizontal plane. Using a “bleaching effect” of the Musca compound eye as an indicator, the angular distances between the optical axes of adjacent ommatidia are measured and found to vary between 2.3 and 3.9 degrees. Thus the visual fields of adjacent ommatidia strongly overlap. Based on these findings a calculation reveals that less than 12% of the mean efficient light flux is received from the anatomically determined visual field of the ommatidium. Similar percentages for Calliphora (less than 20%) and Limulus (less than 19%) result from evaluation of data collected by other investigators. — Light entering the visual element from different directions (more than 5° apart) is demonstrated to be 1.2 to 1.4 times more effective than light received from the same direction. — Consequences of the overlap of visual fields of adjacent ommatidia for perception of motions and patterns by the compound eye are discussed.

Immediate Memory and Simultaneous Visual Stimulation

Ten right-handed, right eye-dominant aircrew trainees recalled digits and colours projected simultaneously one to each eye, under five binocular viewing conditions that precluded overlap in visual fields. Results of this experiment favour the view that Broadbent's theory of immediate memory is a special case which, though not typical, is applicable to vision. Relevance of present findings for the problem of cerebral dominance is also discussed.