Kanizsa's Shrinkage Illusion Produced by a Misapplied 3-D Corrective Mechanism

Perception ◽  
10.1068/p5326 ◽  
2005 ◽  
Vol 34 (10) ◽  
pp. 1181-1192 ◽  
Author(s):  
Esther G González ◽  
Hiroshi Ono ◽  
Elaine Lam ◽  
Martin J Steinbach
Keyword(s):  
Visual System ◽  
Binocular Vision ◽  
Monocular Vision ◽  
Two Dimensional ◽  
Shape Distortion ◽  
The Right ◽  
Partially Occluded ◽  
Cyclopean View ◽  
Normal Binocular Vision

In order to include the monocular areas from the left and the right eye in the cyclopean view, the visual system displaces the occluded elements which would result in a horizontal elongation of the shape but does not occur thanks to a correction mechanism which preserves the shape. We hypothesised that this mechanism causes Kanizsa's a modal shrinkage illusion (the apparent elongation of a partially occluded square) when it is incorrectly applied by the visual system to a two-dimensional stimulus. Four experiments tested this hypothesis: (i) one-eyed observers were less susceptible to the illusion than people with normal binocular vision because, for them, the correction for shape is unnecessary; (ii) the illusion was stronger with binocular than with monocular vision since binocularity induces the visual system to correct for the shape distortion; (iii) the illusion diminished when the stimulus was rotated 90° given that displacement and compression are not required for vertical occlusion; (iv) the magnitude of the illusion was a function of the width of the occluder because, as previous research has shown, the edges of a partially occluded square are less displaced the farther they are from the edges of the occluder. The data from the four experiments support our hypothesis even though no condition was able to eliminate the illusion; other possible causes are discussed.

scholarly journals Development of Binocular Vision

2014 ◽  
Vol 3 (1) ◽  
Author(s):  
Muhammad Syauqie ◽  
Sri Handayani Mega Putri
Keyword(s):  
Visual Acuity ◽  
Binocular Vision ◽  
Monocular Vision ◽  
Three Dimensions ◽  
Sensitive Period ◽  
Visual Axis ◽  
Sensory Fusion ◽  
Vision Development ◽  
The World ◽  
Normal Binocular Vision

AbstrakPenglihatan binokular secara harfiah berarti penglihatan dengan 2 mata dan dengan adanya penglihatan binokular, kita dapat melihat dunia dalam 3 dimensi meskipun bayangan yang jatuh pada kedua retina merupakan bayangan 2 dimensi. Penglihatan binokular juga memberikan beberapa keuntungan berupa ketajaman visual, kontras sensitivitas, dan lapangan pandang penglihatan yang lebih baik dibandingkan dengan penglihatan monokular. Penglihatan binokular normal memerlukan aksis visual yang jernih, fusi sensoris, dan fusi motoris. Pada manusia, periode sensitif dari perkembangan penglihatan binokular dimulai pada usia sekitar 3 bulan, mencapai puncaknya pada usia 1 hingga 3 tahun, telah berkembang sempurna pada usia 4 tahun dan secara perlahan menurun hingga berhenti pada usia 9 tahun. Berbagai hambatan, berupa hambatan sensoris, motoris,dan sentral, dalam jalur refleks sangat mungkin akan menghambat perkembangan dari penglihatan binokular terutama pada periode sensitif sewaktu 2 tahun pertama kehidupan.Kata kunci: penglihatan binokular, perkembangan, fusi, stereopsisAbstractBinocular vision literally means vision with two eyes and with binocular vision, we can see the world in three dimensions even though the images that fall on both of the retina were the 2-dimensional images. Binocular vision also provide some advantages included improved visual acuity, contrast sensitivity, and visual field compared with monocular vision. Normal binocular vision requires a clear visual axis, sensory fusion, and motoric fusion. In human, the sensitive period of binocular vision development began at around 3 months of age, reaching its peak at the age of 1 to 3 years, had developed completely at the age of 4 years and gradually declined until it stops at the age of 9 years. Various obstacles, such as sensory, motoric, and central obstacles, within the reflex pathway were very likely to inhibited the development of binocular vision, especially in sensitive period during the first 2 years of life.Keywords: binocular vision, development, fusion, stereopsis

scholarly journals Effect of corneal refractive surgery on accommodative and binocular dysfunctions among civilian pilots in Southwest China

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Ye Wu ◽  
Zhen Zhang ◽  
Meng Liao ◽  
Qi Li ◽  
Xue Lin Tang ◽  
...  
Keyword(s):  
Binocular Vision ◽  
Refractive Surgery ◽  
Visual Symptom ◽  
Chi Square ◽  
Visual Symptoms ◽  
Significant Difference ◽  
Symptom Scores ◽  
Chi Square Test ◽  
Corneal Refractive Surgery ◽  
Normal Binocular Vision

Abstract Background To analyze whether corneal refractive surgery (CRS) is associated with the distribution of different accommodative dysfunctions (ADs) and binocular dysfunctions (BDs) in civilian pilots. A further aim was to analyze the percentages and visual symptoms associated with ADs and/or BDs in this population. Methods One hundred and eight civilian pilots who underwent CRS from January 2001 to July 2012 (age: 30.33 ± 4.60 years) were enrolled, the mean preoperative SE was − 1.51 ± 1.15 D (range: − 1.00- − 5.00 D). Ninety-nine emmetropic civilian pilots (age: 29.64 ± 3.77 years) who were age- and sex-matched to the CRS group were also enrolled. Refractive status, accommodative and binocular tests of each subject were performed. Visually related symptoms were quantified using the 19-item College of Optometrists in Vision Development Quality of Life (COVD-QOL) questionnaire. The 19 items were summed to obtain visual symptom scores that might indicate visual dysfunctions. The chi-square test was used to analyze differences in percentages of ADs and/or BDs between the CRS and emmetropic groups. The Mann-Whitney U test was used to compare visual symptom scores between pilots with ADs and/or BDs and pilots with normal binocular vision. Results No significant difference was observed between the CRS and emmetropic groups in the overall prevalence of ADs and BDs (15.7% and 15.2% in the CRS and emmetropic groups, respectively; P = 0.185). ADs were present in 4.63% and 3.03% of the CRS and emmetropic group, respectively. BDs were observed in 11.1% and 12.1% of the CRS and emmetropic group, respectively, yielding no significant differences between the groups in the prevalence of ADs or BDs (AD: P = 0.094; BD: P = 0.105). Pilots with ADs and/or BDs had significantly more visual symptoms than pilots with normal binocular vision (p < 0.001). Conclusions CRS for civilian pilots with low-moderate myopia might not impact binocular functions. ADs and/or BDs commonly occur in both emmetropia pilots and pilots who undergo CRS, and pilots with ADs and/or BDs are associated with increased symptoms. This study confirms the importance of a full assessment of binocular visual functions in detecting and remedying these dysfunctions in this specific population.

scholarly journals On local and integrated stress-tensor commutators

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Mert Besken ◽  
Jan de Boer ◽  
Grégoire Mathys
Keyword(s):  
Stress Tensor ◽  
Free Field ◽  
Virasoro Algebra ◽  
Light Sheet ◽  
Operator Product ◽  
Local Form ◽  
Two Dimensional ◽  
Conformal Embedding ◽  
General Aspects ◽  
The Right

Abstract We discuss some general aspects of commutators of local operators in Lorentzian CFTs, which can be obtained from a suitable analytic continuation of the Euclidean operator product expansion (OPE). Commutators only make sense as distributions, and care has to be taken to extract the right distribution from the OPE. We provide explicit computations in two and four-dimensional CFTs, focusing mainly on commutators of components of the stress-tensor. We rederive several familiar results, such as the canonical commutation relations of free field theory, the local form of the Poincaré algebra, and the Virasoro algebra of two-dimensional CFT. We then consider commutators of light-ray operators built from the stress-tensor. Using simplifying features of the light sheet limit in four-dimensional CFT we provide a direct computation of the BMS algebra formed by a specific set of light-ray operators in theories with no light scalar conformal primaries. In four-dimensional CFT we define a new infinite set of light-ray operators constructed from the stress-tensor, which all have well-defined matrix elements. These are a direct generalization of the two-dimensional Virasoro light-ray operators that are obtained from a conformal embedding of Minkowski space in the Lorentzian cylinder. They obey Hermiticity conditions similar to their two-dimensional analogues, and also share the property that a semi-infinite subset annihilates the vacuum.

Displaying Depth in Computer Systems: Lessons from Two-Dimensional Works of Art

2005 ◽  
Vol 49 (17) ◽  
pp. 1583-1587
Author(s):  
Skye Lee Pazuchanics ◽  
Douglas J. Gillan
Keyword(s):  
Visual System ◽  
Computer Systems ◽  
Cue Integration ◽  
Two Dimensional ◽  
Cue Combination ◽  
Design Decisions ◽  
Works Of Art ◽  
Pictorial Cues

Virtual depth displays depend on static, monocular cues. Models of integrating monocular cues may be continuous (additive) or discontinuous. Previous research using simple displays and a small number of cues supported continuous cue integration. The present research is designed to expand the understanding of how the visual system integrates information from multiple pictorial cues by investigating combinations of one to ten pictorial cues in visually-rich, two-dimensional displays (paintings and photographs). Participants estimated depth in target paintings and photographs relative to a standard two dimensional display. Certain results suggest that the visual system integrates cues in a largely additive way, but after a number of cues are present there may be an additional boost in perceived depth resulting in a best-fittingdiscontinuous model of cue combination. However, this discontinuous effect may be due to designdecisions made by the painters rather than exclusively to the perceptual processes of the viewers. Analyses of these design decisions provide lessons for the design of two-dimensional displays.

scholarly journals Ocular Echobiometry and Resistivity Index of External Ophthalmic Artery in Agoutis (Dasyprocta prymnolopha)

2021 ◽  
Vol 49 ◽  
Author(s):  
Sabrina Barros Araújo ◽  
Flávio Ribeiro Alves ◽  
Gerson Tavares Pessoa ◽  
Renan Paraguassu De Sá Rodrigues ◽  
Laecio Da Silva Moura ◽  
...  
Keyword(s):  
Anterior Chamber ◽  
Ophthalmic Artery ◽  
Color Doppler ◽  
Two Dimensional ◽  
Wild Rodents ◽  
Resistivity Index ◽  
Lens Thickness ◽  
Ocular Ultrasound ◽  
The Mean ◽  
The Right

Background: Veterinary Ophthalmology provides complementary information for the diagnosis of ocular pathologies. Studies in wild species are essential. Among the diagnostic techniques in ophthalmology, two-dimensional ultrasonography stands out. The agouti is a rodent belonging to the Dasyproctidae family that has been widely used as an experimental model. For these animals, sight is one of the crucial senses for their survival. The aim of this study was to evaluate the effectiveness of the two-dimensional ocular ultrasound technique to obtain anatomical measurements and the external ophthalmic artery resistivity index, presumably normal in the species Dasyprocta prymnolopha.Materials, Methods & Results: Forty eye bulbs of 20 adult rodents of the species were evaluated by ultrasonography. In these animals, B-mode echobiometry was performed using the transpalpebral approach and the hemodynamic study of the external ophthalmic artery using the color Doppler technique. All examinations were initiated by the left eye bulb and all measurements were performed by only one examiner. The collected data related to echobiometry were analyzed using Bioest 5.0 for Windows. Initially, normality was tested using the Shapiro-Wilk test for each parameter, then the paired t-test was performed, comparing right and left eyes, and a significance level of 5% (P < 0.05) was adopted. Based on the methodology used, the following values were obtained for the right and left eyeballs, respectively: anterior chamber thickness - mean of 1.28 ± 0.3 mm and 1.22 ± 0.1 mm; lens thickness - 8.27 ± 0.9 mm and 8.11 ± 0.9 mm; vitreous chamber thickness - 5.35 ± 0.48 mm and 5.30 ± 0.47 mm and axial length - 12.7 ± 0.9 mm and 13 ± 0.68 mm. The mean external ophthalmic artery resistivity values were 0.4305 ± 0.0390 and 0.4258 ± 0.0387 (right and left eye, respectively), characterizing a low resistance. There was no statistical difference between the right and left eyeballs in any of the studied parameters.Discussion: The use of the convex transducer was feasible, promoting adequate contact with the ocular surface and images of satisfactory quality for obtaining measurements, similar to what was observed in studies evaluating the ocular biometry of primates and dogs. The anterior chamber thickness values in this experiment did not differ statistically between the antimers, as well as observed for dogs. The data obtained for lens thickness did not differ statistically for antimers, like those obtained for other rodent species evaluated with the same methodology. The mean values of vitreous chamber thickness were like those observed in chinchillas but correspond to about half of that obtained for capybaras. In this study, the external ophthalmic artery was characterized in all animals, but obtaining the spectral tracing was difficult due to its fine caliber. In wild animals, and especially in wild rodents, there are few data reporting the resistivity of the ophthalmic artery, and there is a lack of studies, which can be explained by the behavioral characteristics of defense and by the high susceptibility to stress in capture, since the performing the technique requires, as in other procedures, the use of chemical containment.Keywords: Doppler flow, ultrasound, eye, agouti.

scholarly journals Application of the Modified Вagolini Test in the Diagnosis of Binocular Vision Disorders

2020 ◽  
Vol 17 (3) ◽  
pp. 435-441
Author(s):  
S. I. Rychkova ◽  
V. G. Likhvantseva
Keyword(s):  
Binocular Vision ◽  
Quantitative Assessment ◽  
Qualitative Evaluation ◽  
High Sensitivity ◽  
Qualitative Assessment ◽  
Control Group ◽  
Color Test ◽  
Functional Correction ◽  
Personalized Approach ◽  
The Right

The work is devoted to one of the most actual problems of current strabismology — the development of effective ways to study binocular vision.The purpose — to study the effectiveness of the developed modification of the Bagolini test in the diagnostics of binocular disorders.Patients and methods. 240 patients with non-paralytic strabismus aged from 6 to 17 (on average 10.8 ± 0.24) years were observed. There were 190 patients with converging strabismus and 50 patients with diverging strabismus. The control group consisted of 180 children aged also from 6 to 17 (on average 10.9 ± 0.3) years without ophthalmopathology. All children were examined for the character of vision using a Worth-test, the classic Bagolini test (CTB), and the developed modified Bagolini test (MTB). If the patient has a strabismus angle, the study was performed in two variants: without prismatic deviation compensation (under the subjective angle of strabismus — SU) and under full prismatic compensation (under the objective angle of strabismus — OU). For qualitative assessment of binocular vision with MTB, static presentation of the test image was used, for quantitative assessment — alternating (alternate presentation of details corresponding to the right and left eyes).Results. The qualitative evaluation data obtained with the help of MTB made it possible to differentiate patients with non-permanent regional functional scotoma of suppression (FSP) and patients with stable bifoveal fusion among children with binocular vision by color test, and to distinguish patients with regional stable FSP and total FSP among children with monocular vision by color test. In the study under SU, the sensitivity of the method was 97.8 % and specificity 96.2 %, under OU — 96.6 % and 92.7 %, correspondingly. Using quantitative evaluation, it was found that the minimum duration of monocular phases required to eliminate functional inhibition in children with total FSP is twice as long as in children with regional FSP (z = 6,303, df 52, p < 0.001 according to the Mann — Whitney criterion).Conclusion. Thus, the modified Bagolini test developed by us is an effective way of qualitative and quantitative assessment of the state of binocular vision. The method has a high sensitivity and specificity, combines the capabilities of anaglyphic and phase haploscopy, and can be used for a personalized approach to the selection of conditions and modes of functional correction of binocular disorders, as well as for monitoring binocular vision during treatment. 

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