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Perception Sep 2023The origin of depth in Panum's limiting case is unclear at present, so we investigated the depth perception mechanism using a triangle type of Panum's stimulus with a...
The origin of depth in Panum's limiting case is unclear at present, so we investigated the depth perception mechanism using a triangle type of Panum's stimulus with a slant effect and clear criterion. Experiment 1 explored whether participants can correctly perceive fixation and nonfixation features using the fixation point and quick representation of stimuli, then examined whether participants' depth judgments supported double fusion or single fusion. The results of Experiment 1 showed that participants could correctly perceive the depth of fixation and nonfixation features. That is, it supported double fusion. In Experiment 2, we examined whether the depth perceived by observers comes from depth contrast. The results of Experiment 2 showed that the depth of the two features perceived after binocular fusion did not originate from the depth contrast. The findings suggest that the depth perception mechanism of Panum's limiting case is more likely to be double fusion.
Topics: Depth Perception; Vision Disparity; Humans; Fixation, Ocular; Photic Stimulation; Models, Neurological; Reproducibility of Results; Male; Female; Young Adult; Adult; Analysis of Variance; Contrast Sensitivity
PubMed: 37408435
DOI: 10.1177/03010066231177513 -
Vision Research Aug 2024Rectangularity and perpendicularity of contours are important properties of 3D shape for the visual system and the visual system can use them asa prioriconstraints for... (Review)
Review
Rectangularity and perpendicularity of contours are important properties of 3D shape for the visual system and the visual system can use them asa prioriconstraints for perceivingshape veridically. The presentarticle provides a comprehensive review ofpriorstudiesofthe perception of rectangularity and perpendicularity anditdiscussestheir effects on3D shape perception from both theoretical and empiricalapproaches. It has been shown that the visual system is biased to perceive a rectangular 3D shape from a 2D image. We thought that this bias might be attributable to the likelihood of a rectangular interpretation but this hypothesis is not supported by the results of our psychophysical experiment. Note that the perception ofa rectangular shape cannot be explained solely on the basis of geometry. A rectangular shape is perceived from an image that is inconsistent with a rectangular interpretation. To address thisissue, we developed a computational model that can recover a rectangular shape from an image of a parallelopiped. The model allows the recovered shape to be slightly inconsistent so that the recovered shape satisfies the a priori constraints of maximum compactness and minimal surface area. This model captures someof thephenomenaassociated withthe perception of the rectangular shape that were reported inpriorstudies. This finding suggests that rectangularity works for shape perception by incorporatingitwith someadditionalconstraints.
Topics: Humans; Form Perception; Psychophysics; Depth Perception; Pattern Recognition, Visual; Photic Stimulation
PubMed: 38772272
DOI: 10.1016/j.visres.2024.108433 -
Translational Psychiatry May 2024Bi-stable stimuli evoke two distinct perceptual interpretations that alternate and compete for dominance. Bi-stable perception is thought to be driven at least in part...
Bi-stable stimuli evoke two distinct perceptual interpretations that alternate and compete for dominance. Bi-stable perception is thought to be driven at least in part by mutual suppression between distinct neural populations that represent each percept. Abnormal visual perception has been observed among people with psychotic psychopathology (PwPP), and there is evidence to suggest that these visual deficits may depend on impaired neural suppression in the visual cortex. However, it is not yet clear whether bi-stable visual perception is abnormal among PwPP. Here, we examined bi-stable perception in a visual structure-from-motion task using a rotating cylinder illusion in a group of 65 PwPP, 44 first-degree biological relatives, and 43 healthy controls. Data from a 'real switch' task, in which physical depth cues signaled real switches in rotation direction were used to exclude individuals who did not show adequate task performance. In addition, we measured concentrations of neurochemicals, including glutamate, glutamine, and γ-amino butyric acid (GABA), involved in excitatory and inhibitory neurotransmission. These neurochemicals were measured non-invasively in the visual cortex using 7 tesla MR spectroscopy. We found that PwPP and their relatives showed faster bi-stable switch rates than healthy controls. Faster switch rates also correlated with significantly higher psychiatric symptom levels, specifically disorganization, across all participants. However, we did not observe any significant relationships across individuals between neurochemical concentrations and SFM switch rates. Our results are consistent with a reduction in suppressive neural processes during structure-from-motion perception in PwPP, and suggest that genetic liability for psychosis is associated with disrupted bi-stable perception.
Topics: Humans; Male; Female; Adult; Psychotic Disorders; Visual Cortex; Visual Perception; Young Adult; Motion Perception; Magnetic Resonance Spectroscopy; Middle Aged
PubMed: 38714650
DOI: 10.1038/s41398-024-02913-z -
IEEE Transactions on Visualization and... Oct 2023360° images and videos have become an economic and popular way to provide VR experiences using real-world content. However, the manipulation of the stereo panoramic...
360° images and videos have become an economic and popular way to provide VR experiences using real-world content. However, the manipulation of the stereo panoramic content remains less explored. In this paper, we focus on the 360° image composition problem, and develop a solution that can take an object from a stereo image pair and insert it at a given 3D position in a target stereo panorama, with well-preserved geometry information. Our method uses recovered 3D point clouds to guide the composited image generation. More specifically, we observe that using only a one-off operation to insert objects into equirectangular images will never produce satisfactory depth perception and generate ghost artifacts when users are watching the result from different view directions. Therefore, we propose a novel per-view projection method that segments the object in 3D spherical space with the stereo camera pair facing in that direction. A deep depth densification network is proposed to generate depth guidance for the stereo image generation of each view segment according to the desired position and pose of the inserted object. We finally combine the synthesized view segments and blend the objects into the target stereo 360° scene. A user study demonstrates that our method can provide good depth perception and removes ghost artifacts. The per-view solution is a potential paradigm for other content manipulation methods for 360° images and videos.
PubMed: 37889815
DOI: 10.1109/TVCG.2023.3327943 -
Eye and Brain 2023Parkinson's disease (PD) affects approximately 10 million individuals worldwide. Visual impairments are a common feature of PD. Patients report difficulties with visual... (Review)
Review
Parkinson's disease (PD) affects approximately 10 million individuals worldwide. Visual impairments are a common feature of PD. Patients report difficulties with visual scanning, impaired depth perception and spatial navigation, and blurry and double vision. Examination of PD patients reveals abnormal fixational saccades, strabismus, impaired convergence, and abnormal visually-guided saccades. This review aims to describe objective features of abnormal eye movements in PD and to discuss the structures and pathways through which these abnormalities may manifest.
PubMed: 37519412
DOI: 10.2147/EB.S384763 -
IEEE Transactions on Visualization and... Nov 2023This paper investigates the accuracy of Augmented Reality (AR) technologies, particularly commercially available optical see-through displays, in depicting virtual...
This paper investigates the accuracy of Augmented Reality (AR) technologies, particularly commercially available optical see-through displays, in depicting virtual content inside the human body for surgical planning. Their inherent limitations result in inaccuracies in perceived object positioning. We examine how occlusion, specifically with opaque surfaces, affects perceived depth of virtual objects at arm's length working distances. A custom apparatus with a half-silvered mirror was developed, providing accurate depth cues excluding occlusion, differing from commercial displays. We carried out a study, contrasting our apparatus with a HoloLens 2, involving a depth estimation task under varied surface complexities and illuminations. In addition, we explored the effects of creating a virtual "hole" in the surface. Subjects' depth estimation accuracy and confidence were a ssessed. Results showed more depth estimation variation with HoloLens and significant depth error beneath complex occluding surfaces. However, creating a virtual hole significantly reduced depth errors and increased subjects' confidence, irrespective of accuracy enhancement. These findings have important implications for the design and use of mixed-reality technologies in surgical applications, and industrial applications such as using virtual content to guide maintenance or repair of components hidden beneath the opaque outer surface of equipment. A free copy of this paper and all supplemental materials are available at https://bit.ly/3YbkwjU.
Topics: Humans; Arm; Computer Graphics; Augmented Reality; User-Computer Interface; Depth Perception
PubMed: 37782607
DOI: 10.1109/TVCG.2023.3320239 -
Frontiers in Public Health 2023Tuberculosis (TB)-related knowledge is an important evaluation metric for health education interventions. Factor analysis is limited when used on ordinal scales and does...
Development and validation of assessment instrument for the perception and attitude toward tuberculosis among the general population in Indonesia: a Rasch analysis of psychometric properties.
INTRODUCTION
Tuberculosis (TB)-related knowledge is an important evaluation metric for health education interventions. Factor analysis is limited when used on ordinal scales and does not provide in-depth item function examinations, whereas Rasch analysis addresses these limitations and offers potential advantages such as generalizability, testing of unidimensionality, producing an ordered set of items, and identifying poorly functioning items. Therefore, this research aims to develop a reliable and valid measure of perception and attitude toward TB (PATT) for public application use Rasch Analysis.
METHODS
A questionnaire-based survey was conducted on the Indonesian general population using the Google Form platform. Rasch analysis was then employed to examine the psychometric properties and develop the final items of PATT.
RESULTS
Experts from across the TB community participated in the PATT development, producing an initial scale of 16 items. Up to 1,616 participants completed the PATT questionnaire, where 74.8% were female, and 5% had a TB history. The final unidimensional 16-item scale has an item reliability of 1.00 for the two components (perception and attitude), a person reliability index of 0.87 and 0.60, as well as a Cronbach's test reliability of 0.88 and 0.88 for perception and attitude, respectively.
CONCLUSION
The PATT is a unidimensional scale with good construct validity and internal consistency. It has the potential to be useful for the assessment of TB perception and attitude in research and clinical practice.
Topics: Humans; Female; Male; Psychometrics; Indonesia; Reproducibility of Results; Tuberculosis; Perception
PubMed: 37841718
DOI: 10.3389/fpubh.2023.1143120 -
Experimental Eye Research Nov 2023To investigate the impact of p38 mitogen-activated protein kinase (MAPK) signaling on reactivating visual cortical plasticity in adult amblyopic mice.
OBJECTIVE
To investigate the impact of p38 mitogen-activated protein kinase (MAPK) signaling on reactivating visual cortical plasticity in adult amblyopic mice.
MATERIALS AND METHODS
Reverse suture (RS), environment enrichment (EE), and combined with left intracerebroventricular injection of p38 MAPK inhibitor (SB203580, SB) or p38 MAPK agonist (dehydrocorydaline hydrochloride, DHC) were utilized to treat adult amblyopic mice with monocular deprivation (MD). The visual water task, visual cliff test, and Flash visual-evoked potential were used to measure the visual function. Then, Golgi staining and transmission electron microscopy were used to assess the reactivation of structural plasticity in adult amblyopic mice. Western blot and immunohistochemistry detected the expression of ATF2, PSD-95, p38 MAPK, and phospho-p38 MAPK in the left visual cortex.
RESULTS
No statistically significant difference was observed in the visual function in each pre-intervention group. Compared to pre-intervention, the visual acuity of deprived eyes was improved significantly, the impairment of visual depth perception was alleviated, and the P wave amplitude and C/I ratio were increased in the EE + RS, the EE + RS + SB, and the EE + RS + DMSO groups, but no significant difference was detected in the EE + RS + DHC group. Compared to EE + RS + DHC group, the density of dendritic spines was significantly higher, the synaptic density of the left visual cortex increased significantly, the length of the active synaptic zone increased, and the thickness of post-synaptic density (PSD) thickened in the left visual cortex of EE + RS, EE + RS + SB, and EE + RS + DMSO groups. And that, the protein expression of p-p38 MAPK increased while that of PSD-95 and ATF2 decreased significantly in the left visual cortex of the EE + RS + DHC group mice.
CONCLUSION
RS and EE intervention improved the visual function and synaptic plasticity of the visual cortex in adult amblyopic mice. However, activating p38 MAPK hinders the recovery of visual function by upregulating the phosphorylation of p38 MAPK and decreasing the ATF2 protein expression.
Topics: Mice; Animals; p38 Mitogen-Activated Protein Kinases; Dimethyl Sulfoxide; Visual Cortex; Amblyopia; Vision, Ocular
PubMed: 37748716
DOI: 10.1016/j.exer.2023.109651 -
IEEE Transactions on Ultrasonics,... Sep 2023Under the situation of severe COVID-19 epidemic, lung ultrasound (LUS) has been proved to be an effective and convenient method to diagnose and evaluate the extent of...
Under the situation of severe COVID-19 epidemic, lung ultrasound (LUS) has been proved to be an effective and convenient method to diagnose and evaluate the extent of respiratory disease. However, the traditional clinical ultrasound (US) scanning requires doctors not only to be in close contact with patients but also to have rich experience. In order to alleviate the shortage of medical resources and reduce the work stress and risk of infection for doctors, we propose a visual perception and convolutional neural network (CNN)-based robotic autonomous LUS scanning localization system to realize scanned target recognition, probe pose solution and movement, and the acquisition of US images. The LUS scanned targets are identified through the target segmentation and localization algorithm based on the improved CNN, which is using the depth camera to collect the image information; furthermore, the method based on multiscale compensation normal vector is used to solve the attitude of the probe; finally, a position control strategy based on force feedback is designed to optimize the position and attitude of the probe, which can not only obtain high-quality US images but also ensure the safety of patients and the system. The results of human LUS scanning experiment verify the accuracy and feasibility of the system. The positioning accuracy of the scanned targets is 15.63 ± 0.18 mm, and the distance accuracy and rotation angle accuracy of the probe position calculation are 6.38 ± 0.25 mm and 8.60 ±2.29 , respectively. More importantly, the obtained high-quality US images can clearly capture the main pathological features of the lung. The system is expected to be applied in clinical practice.
Topics: Humans; Robotic Surgical Procedures; COVID-19; Neural Networks, Computer; Lung; Visual Perception
PubMed: 37015119
DOI: 10.1109/TUFFC.2023.3263514 -
Journal of Vision Apr 2024The perceived slant of a stereoscopic surface is altered by the presence of a surrounding surface, a phenomenon termed stereo slant contrast. Previous studies have shown...
The perceived slant of a stereoscopic surface is altered by the presence of a surrounding surface, a phenomenon termed stereo slant contrast. Previous studies have shown that a slanted surround causes a fronto-parallel surface to appear slanted in the opposite direction, an instance of "bidirectional" contrast. A few studies have examined slant contrast using slanted as opposed to fronto-parallel test surfaces, and these also have shown slant contrast. Here, we use a matching method to examine slant contrast over a wide range of combinations of surround and test slants, one aim being to determine whether stereo slant contrast transfers across opposite directions of test and surround slant. We also examine the effect of the test on the perceived slant of the surround. Test slant contrast was found to be bidirectional in virtually all test-surround combinations and transferred across opposite test and surround slants, with little or no decline in magnitude as the test-surround slant difference approached the limit. There was a weak bidirectional effect of the test slant on the perceived slant of the surround. We consider how our results might be explained by four mechanisms: (a) normalization of stereo slant to vertical; (b) divisive normalization of stereo slant channels in a manner analogous to the tilt illusion; (c) interactions between center and surround disparity-gradient detectors; and (d) uncertainty in slant estimation. We conclude that the third of these (interactions between center and surround disparity-gradient detectors) is the most likely cause of stereo slant contrast.
Topics: Humans; Depth Perception; Contrast Sensitivity; Photic Stimulation; Vision, Binocular
PubMed: 38683571
DOI: 10.1167/jov.24.4.24