Difference in Recognition of Optical Illusion Using Visual and Tactual Sense

Visual illusions occur around us all the time, which present in nature and appear when you least expect it. It is well known that visual illusions can have a dramatic effect upon our visual perception of an object 's size and position. However, whether visual illusions have a similar influence on visual guided action or not, it remains the subject of much debate. The purpose of this study is to explore whether the visual information used to identify and categorize an object would be similar to the visual information used to plan and control visually guided movements directed toward that object. The outcome of this study will be helpful for designers to understand our visual information system and apply that knowledge to the design practice. In order to achieve the purpose of this study mentioned above, three visual illusions as the experiment's apparatus are applied to examine the relative effect of visual illusions on both the visual perceived center of an object and the position of a grasp on that object when a balanced lift is required. The results of the experiment show that (1) Illusions influence both the perceived and the grasped estimates of the center position, but the grasp center is more veridical; (2) Judd-illusion, one of the three visual illusions, has a bigger degree of effect than two other illusions on both the perceived and the grasped estimates of the center position; (3) By providing the participants with a mean to guide their visual perception of these illusions, the errors from the estimation of the center position can be significantly reduced.

Luria (Luria, Cognitive development: Its cultural and social foundations, Harvard University Press, 1976) famously observed that people who never learnt to read and write do not perceive visual illusions. We conducted a conceptual replication of the Luria study of the effect of literacy on the processing of visual illusions. We designed two carefully controlled experiments with 161 participants with varying literacy levels ranging from complete illiterates to high literates in Chennai, India. Accuracy and reaction time in the identification of visual shape and color illusions and the identification of appropriate control images were measured. Separate statistical analyses of Experiments 1 and 2 as well as pooled analyses of both experiments do not provide any support for the notion that literacy affects the perception of visual illusions. Our large sample, carefully controlled study strongly suggests that literacy does not meaningfully affect the identification of visual illusions and raises some questions about other reports of cultural effects on illusion perception.

The science and technology of image transmission and display has evolved primarily from the diciplines of computer science, electrical engineering and physics. Thus, it is only natural that techniques and attitudes which have developed are characterized by the style in which people in these areas approach the subject of images and their transmission, display, and processing. For example, one finds many important differences between the methods of television and those of photography. Moreover, an even greater contrast is found when comparing the methods of electrical engineering, physics, television and photography with those now understood to be employed by the human eye and the human visual system. Specifically, let us contrast the method by which television, photography and the human visual system, represent image information. In television (particularly digital imaging), image values are represented by signals analogous to quantities of light. They are called intensities. In photography, on the other hand, the representing quantities are concentrations of silver or dyes. Consequently, due to the natural exponentiating laws governing the interaction of light with these media, they are analogous to the logarithm of quantities of light. They are called densities. The human visual system, on the other hand, (while being generally logarithmically sensitive) moves a large step further away from representation by physical quantities of light and produces at very early stages in its processing highly modified versions of the patterns of light or their logarithms. The natural question then arrises, why should the human visual system try to do this; and since it does, what consequences are implied in terms of the television and photographic presentations normally employed?

Introduction: The present study sets out to determine which sensory system mostly influences self-motion perception when visual and vestibular cues are in conflict. We paired caloric vestibular stimulation that signaled motion in either the clockwise or counter-clockwise direction with a visual display that indicated self-rotation in either the same or opposite directions.Methods: In Experiment 1 (E1), caloric vestibular stimulation was used to produce vestibular circular vection. In Experiment 2 (E2), a virtual optokinetic drum was used to produce visual circular vection in a VR headset. Vection speed, direction, and duration were recorded using a potentiometer knob the participant controlled in E1 and E2. In Experiment 3 (E3), visual and vestibular stimuli were matched to be at approximately equal speeds across visual and vestibular modalities for each participant setting up Experiment 4 (E4). In E4, participants observed a moving visual pattern in a virtual reality (VR) headset while receiving caloric vestibular stimulation. Participants rotated the potentiometer knob while attending to visual–vestibular stimuli presentations to indicate their perceived circular vection. E4 had two conditions: 1) A congruent condition where calorics and visual display indicated circular vection in the same direction; 2) an incongruent condition where calorics and visual display indicated circular vection in opposite directions.Results and discussion: There were equal reports of knob rotation in the direction consistent with the visual and vestibular self-rotation direction in the incongruent condition of E4 across trials. There were no significant differences in knob rotation speed and duration in both conditions. These results demonstrate that the brain appears to weigh visual and vestibular cues equally during a visual–vestibular conflict of approximately equal speeds. These results are most consistent with the optimal cue integration hypothesis.

2 - The human visual system described through visual illusions

Defining visual illusions in Parkinson's disease: Kinetopsia and object misidentification illusions

Visual illusions affect both movement planning and on-line control: A multiple cue position on bias and goal-directed action

Objective To observe and explore the therapeutic efficacy of hyperbaric oxygen (HBO) in the treatment of non-arteritic anterior ischemic optic neuropathy (NAION). Methods A total of 139 NAION patients were randomly divided into a control group of 72 and a hyperbaric oxygen group of 67. Both groups were given conventional drugs including prednisolone, mecobalamin and compound anisodine, while the hyperbaric oxygen group was additionally provided with hyperbaric oxygen treatment at a pressure of 0.2MPa once a day for 30 days. Each day′s treatment lasted for 110 minutes, including 20 minutes at increasing pressure, 20 minutes decreasing and 60 minutes with the pressure stable at 0.2MPa. Before and after the 30-day treatment, the visual acuity and visual mean sensitivity (MS) of the two groups were observed and compared. Results There was no significant difference between the control group and the hyperbaric oxygen group in terms of average visual acuity or visual MS before the treatment. Afterward the average visual acuity (4.88±0.25) and visual MS (16.68±1.19) of the hyperbaric oxygen group were significantly higher than before the treatment and significantly better than those of the control group. The total effective rate of the hyperbaric oxygen group was 91%, significantly higher than that of the control group (75%). Conclusions Conventional treatment combined with hyperbaric oxygen therapy can significantly promote the visual acuity and visual MS of NAION patients. Key words: Optic neuropathy; Ischemia; Hyperbaric oxygen therapy; Field of view; Visual sensitivity

Seizures originating in the occipital areas are relatively uncommon. They are usually characterized by visual hallucinations and illusions or other symptoms related to the eyes and vision. In a 54-year-old woman with occipital lobe epilepsy, complex visual hallucinations, illusions, and migraine-like headache constitute the major clinical manifestations. During focal status epilepticus, ictal electroencephalography revealed rhythmic focal spikes in the right occipital region, rapidly propagating to the right parietal and contralateral occipital areas. Ictal brain single-photon emission computed topography revealed hyperperfusion of the right occipital region. Using a full-field pattern-shift visual evoked potential (VEP) study, we found that the P100 responses on both sides were markedly attenuated in amplitude during occipital focal status epilepticus, whereas the latencies of the VEPs were normal. The amplitude and morphology of P100 responses on both sides, however, returned to the normal range 7 days after cessation of the seizures. In addition to clinical seizure semiology, scalp EEG, SPECT and neuroimaging studies, VEP studies may be used as a supplementary examination tool to provide further information in the patients with occipital lobe seizures or epilepsies.

A computer vision and robotic system for an intelligent workstation

Randomized clinical trials play an increasingly important role in guiding management decisions, and survival curves are the most popular means for summarizing and depicting the results of a clinical trial. However, survival curves may create certain "visual illusions" that can be misinterpreted by the unwary, with potentially adverse effects on patient care. The authors provide a brief outline of the theoretical background of survival curves and explain the origin of the most common visual illusions. Statisticians need to be aware of such potential for misinterpretation of clinical trial data in order to safeguard clinicians against drawing undue inferences and applying them to actual practice.

One of the fundamental problems of computer vision is to extract 3D shape and motion from images. This can be achieved when a scene or object is observed from different viewpoints or over a period of time. There is a wide range of applications, ranging from digitizing cultural heritage to vision-based autonomous robot navigation. This talk will present several approaches to solve this problem. First, we’ll discuss techniques for 3D shape recovery for static objects and scenes. One particular case is the 3D mapping and localization in large environments from images, e.g. urban 3D reconstruction from vehicleborne cameras or localization from cell-phone images. Next, we’ll shift our focus to modeling dynamic scenes, e.g. people who are moving around. In addition to explicitly 3D modeling an event, we'll consider the possibility to perform video-based rendering from casually captured videos. Speaker Bio-Sketch: Marc Pollefeys is a full professor in the Dept. of Computer Science of ETH Zurich since 2007 where he is the head of the Institute for Visual Computing and leads the Computer Vision and Geometry lab. He currently also remains associated with the Dept. of Computer Science of the University of North Carolina at Chapel Hill where he started as an assistant professor in 2002 and became an associate professor in 2005. Before this he was a postdoctoral researcher at the Katholieke Universiteit Leuven in Belgium, where he also received his M.S. and Ph.D. degrees in 1994 and 1999, respectively. His main area of research is computer vision. One of his main research goals is to develop flexible approaches to capture visual representations of real world objects, scenes and events. Dr. Pollefeys has received several prizes for his research, including a Marr prize, an NSF CAREER award, a Packard Fellowship and a European Research Council Starting Grant. He is the author or co-author of more than 130 peer-reviewed publications. He is the General Chair for the European Conference on Computer Vision 2014 (ECCV), was a Program Co-Chair for the IEEE Conference on Computer Vision and Pattern Recognition 2009 (CVPR), was general/program co-chair of the Third Symposium on 3D Data Processing, Visualization and Transmission and has organized workshops and courses at major vision and graphics conferences and has served on the program committees of many conferences. Prof. Pollefeys is/was on the Editorial Board of the IEEE Transactions on Pattern Analysis and Machine Intelligence and the International Journal of Computer Vision as well as several other journals in computer vision, graphics and robotics.

Who does not like visual illusions? Not only do they offer a wondrous experience to viewers, but they also compellingly reveal the inner workings of our visual system. Out of the myriad of existing illusions, however, rarely are they produced thanks to priors about the physics of our world. Here, we present a novel illusion of this kind-the Double Ring Illusion-which demonstrates that a representation of the physical constraint of solidity (i.e., objects cannot pass through one another) shapes perception. Thus, when viewing ambiguously rotating rings that are compatible with multiple interpretations, the percept is strongly altered by the solidity constraint: Observers predominantly perceive the interpretation respecting solidity rather than the alternative interpretation where solidity is violated. A series of experiments first confirmed that observers reliably experienced this illusion. We then demonstrated that the effects of the illusion influence orthogonal perceptual judgments of object width, thus ruling out decision-level processes as a driver of these effects. Furthermore, we showed that the solidity constraint shapes visual processing even when the stimuli are unambiguous thanks to additional motion and depth information. And finally, we found that the visual system predictably makes use of solidity even in contexts other than the Double Ring Illusion. Together, these results demonstrate the existence of a robust prior for solidity in visual processing, guiding the computations of object motion and interaction. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Psychologists are familiar with ‘cheap and dirty’ or ‘fast and frugal’ heuristics, typically efficient but imperfectly reliable ways of solving problem. Much human cognition relies on them, and many seem to be humanly universal. Nevertheless, we are often unaware of using them. This chapter argues that general cognitive heuristics are responsible for philosophical paradoxes just as heuristics built into our visual system are responsible for visual illusions. Examples include paradoxes about vagueness and sorites series; identity over time; conditionals; ascriptions of belief and other intentional attitudes; disquotational principles about truth and falsity; weighing reasons and intersectionality. Heuristics can also deceive us into accepting erroneous counterexamples to philosophical principles. The proper response to such challenges is not scepticism (any more than visual illusions warrant scepticism about visual perception) but a more sophisticated treatment of our evidence in philosophy, just as naïve falsificationism is not the methodology of natural science.

The processing and perception of visual stimuli are greatly dependent on the context in which those stimuli are presented. While this is not always (and indeed is probably not supposed to be) evident when viewing real-world scenes, the abundance of contextual effects is revealed for example by the vast number of different visual illusions. Context can profoundly change the way the visual system processes single visual stimuli. In contrast masking, surround suppression, and crowding, distracting stimuli impair the observer's ability to detect, identify, and make other judgements about visual stimuli. These perceptual phenomena presumably reflect the operation of neural mechanisms that adjust the operating range of the visual system according to the prevailing conditions, or act to reduce responses to redundant stimulus features. This work first investigates the relationship between masking, which is caused by stimuli that are spatially superimposed on a target stimulus, and surround suppression, which is caused by spatially displaced stimuli. This was done using a temporal masking paradigm and measuring the time-courses of masking and surround suppression. The results reveal how the effects of these suppressive interactions are delicately dependent on stimulus timing and suggest that surround suppression acts extremely fast, having an effect on the early part of the neural response. Finally, contextual effects such as surround suppression and crowding are often considered to be automatic processes that occur over fixed areas in the visual field. The final part of this work shows how changing the spatial layout, and consequently the perceptual organization, of the stimuli can dramatically reduce surround suppression and crowding effects, even in conditions where the current models would predict strong effects. Surround suppression and crowding seem to operate only within perceptually homogeneous areas, while stimuli that are perceptually separate, the ones that stand out, are not affected.