scholarly journals Disambiguating Necker cube rotation using a location cue: What types of spatial location signal can the visual system learn?

2010 ◽  
Vol 10 (6) ◽  
pp. 23-23 ◽  
Author(s):  
S. Harrison ◽  
B. Backus
Keyword(s):  
Visual System ◽  
Necker Cube ◽  
Spatial Location

Can Illusory Figures Be Transparent and Opaque at the Same Time?

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 321-321
Author(s):  
F Purghé
Keyword(s):  
Visual System ◽  
Necker Cube ◽  
Special Kind ◽  
Illusory Figure ◽  
Cognitive Problem ◽  
Paradoxical Result ◽  
Contrary Evidence

A simple and convincing way of explaining illusory figures is based upon the idea that the visual system would infer the presence of an occluding object when the inducing pattern shows features, such as indentations or interruptions, that can be logically explained as due to an occlusion. This kind of explanation implies (a) that an illusory figure should be prevented from occurring if there is no logical need for it, and (b) that the illusory figure must be opaque to be effective as an occluding object. It can be shown, however, that illusory figures can emerge even when there is contrary evidence to occlusion. A special kind of stereoscopic Kanizsa-like pattern superimposed onto a picture (an Escher engraving) is capable of inducing clear illusory figures (two rectangles). In this pattern, the illusory figures seem to be transparent with respect to the picture on the background, which remains fully visible through them, but act as opaque surfaces with respect to the inducers. The inducers are parts of a Necker cube which can be clearly seen only when its fragments induce the illusory rectangles, but disappears if the same fragments, being only outlined, are not able to induce them. If this outcome can be regarded as a demonstration that the Necker cube can be seen as an amodally completed object only when it virtually completes itself ‘behind’ the illusory rectangles, one would have to conclude that the same illusory surfaces can be transparent and opaque at the same time. This paradoxical result seems to challenge any interpretation of illusory figures as being due to an intelligent solution to a cognitive problem.

Analogue models of motion perception

1980 ◽  
Vol 290 (1038) ◽  
pp. 117-135 ◽  
Keyword(s):  
Visual System ◽  
Frequency Domain ◽  
Motion Perception ◽  
Apparent Motion ◽  
Spatial Interpolation ◽  
Spatial Location ◽  
Moving Object ◽  
Low Frequencies ◽  
Analogue Models ◽  
Spatial Locations

An object moving in discrete spatial jumps is difficult to distinguish from a continuously moving object, provided the time between jumps is not too great. The extent of this perceived continuity may be measured by probing the perceived spatial location at times between the target jumps, by either a vernier alignment or a stereoscopic technique. As the time between jumps increases the accuracy of spatial interpolation falls, until finally the object is seen only at its actual spatial locations. These results can be analysed in the frequency domain by treating the signal for apparent motion as the analogue of a periodic waveform containing relatively low frequencies (the continuous motion) and higher frequencies giving rise to the discreteness of the motion. If such an input has the higher frequencies progressively removed by physical filtering, it is perceived as increasingly continuous. The fact that such filtering is not necessary for perceived continuity when the discrete jumps occur at rates greater than about 30 Hz suggests that frequencies greater than that limit are removed by the visual system itself.

Binocular Disparity and Head-Up Displays

1980 ◽  
Vol 22 (4) ◽  
pp. 435-444 ◽  
Author(s):  
Christopher P. Gibson
Keyword(s):  
Visual System ◽  
Binocular Disparity ◽  
Spatial Location ◽  
Retinal Disparity ◽  
Visual Discomfort ◽  
Perceptual Effect ◽  
Depth Cues

Collimation errors present in displays such as the head-up display (HUD) will produce retinal disparity on the retinae of the observer and will have the effect of altering the spatial location of the display. It is apparent that this can, in some instances, give rise to visual discomfort. Psychophysical methods were used to examine the sensitivity and the tolerances of the visual system to binocular disparity in HUDs. It was shown that, when left to their own devices, subjects preferred a small positive disparity to exist between the HUD and the outside world and that even small amounts of negative disparity can have a disturbing perceptual effect. The effect is discussed in relation to the contradictory depth cues which can exist in this kind of electro-optical display.

Remote Sensing Image Segmentation Based on Human Visual System Region-Split and Graph Cut

2011 ◽  
Vol 55-57 ◽  
pp. 115-118 ◽  
Author(s):  
Hua Jiang ◽  
Jing Wen
Keyword(s):  
Remote Sensing ◽  
Image Segmentation ◽  
Visual System ◽  
Human Visual System ◽  
Spatial Location ◽  
Remote Sensing Image ◽  
Graph Cut ◽  
Split Method ◽  
Segmentation Quality ◽  
Image Segmentation Algorithm

Aiming at the problem of poor real-time ability of Normalized Cut (NC), this paper suggests a remote sensing image segmentation algorithm based on region-split and graph cut within human visual system (HVS). According to the features of HVS, the algorithm uses region-split method to segment the remote sensing image into a large number of small regions. By integrating gray feature and spatial location of each region, NC is used to segment the image among regions from global view, by which the final segmented image can be generated. Experimental results show that comparing with the traditional NC, operating speed is significantly improved as getting close segmentation quality, and this is a kind of effective method of image segmentation.

scholarly journals Angle Alignment Evokes Perceived Depth and Illusory Surfaces

Perception ◽  
10.1068/p5987 ◽  
2008 ◽  
Vol 37 (10) ◽  
pp. 1471-1487 ◽  
Author(s):  
Robert Shapley ◽  
Marianne Maertens
Keyword(s):  
Visual System ◽  
American Indian ◽  
Necker Cube ◽  
Visual Image ◽  
Paired Comparisons ◽  
Illusory Contours ◽  
Cortical Areas ◽  
Visual Cortical ◽  
Line Patterns ◽  
Akimel O'odham

There is a distinct visual process that triggers the perception of illusory surfaces and contours along the intersections of aligned, zigzag line patterns. Such illusory contours and surfaces are qualitatively different from illusory contours of the Kanizsa type. The illusory contours and surfaces in this case are not the product of occlusion and do not imply occlusion of one surface by another. Rather, the aligned angles in the patterns are combined by the visual system into the perception of a fold or a 3-D corner, as of stairs on a staircase or a wall ending on a floor. The depth impression is ambiguous and reversible like the Necker cube. Such patterns were used by American Indian artists of the Akimel O'odham (Pima) tribe in basketry, and also by modern European and American artists like Josef Albers, Bridget Riley, Victor Vasarely, and Frank Stella. Our research aims to find out what manipulations of the visual image affect perceived depth in such patterns in order to learn about the perceptual mechanisms. Using paired comparisons, we find that human observers perceive depth in such patterns if, and only if, lines in adjacent regions of the patterns join to form angles, and also if, and only if, the angles are aligned precisely to be consistent with a fold or 3-D corner. The amount of perceived depth is graded, depending on the steepness and the density of angles in the aligned-angle pattern. The required precision of the alignment implies that early retinotopic visual cortical areas may be involved in this perceptual behavior, but the linkage of form with perceived depth suggests involvement of higher cortical areas as well.

scholarly journals Symmetric Networks with Geometric Constraints as Models of Visual Illusions

Symmetry ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 799 ◽  
Author(s):  
Ian Stewart ◽  
Martin Golubitsky
Keyword(s):  
Hopf Bifurcation ◽  
Visual System ◽  
Dynamic Systems ◽  
Necker Cube ◽  
Visual Illusions ◽  
Geometric Constraints ◽  
Consistency Conditions ◽  
Geometric Consistency ◽  
Attribute Levels ◽  
Symmetric Networks

Multistable illusions occur when the visual system interprets the same image in two different ways. We model illusions using dynamic systems based on Wilson networks, which detect combinations of levels of attributes of the image. In most examples presented here, the network has symmetry, which is vital to the analysis of the dynamics. We assume that the visual system has previously learned that certain combinations are geometrically consistent or inconsistent, and model this knowledge by adding suitable excitatory and inhibitory connections between attribute levels. We first discuss 4-node networks for the Necker cube and the rabbit/duck illusion. The main results analyze a more elaborate model for the Necker cube, a 16-node Wilson network whose nodes represent alternative orientations of specific segments of the image. Symmetric Hopf bifurcation is used to show that a small list of natural local geometric consistency conditions leads to alternation between two global percepts: cubes in two different orientations. The model also predicts brief transitional states in which the percept involves impossible rectangles analogous to the Penrose triangle. A tristable illusion generalizing the Necker cube is modelled in a similar manner.

Measuring Object-Centred Attention Based on a Cueing Paradigm

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 220-220
Author(s):  
C Lafosse ◽  
M F Westerhuis ◽  
E Vandenbussche
Keyword(s):  
Target Location ◽  
Necker Cube ◽  
Visual Space ◽  
Spatial Location ◽  
Uncued Location ◽  
Object Based ◽  
Model Configuration ◽  
Significant Difference ◽  
The Subject ◽  
The Difference

Visual attention can be allocated to a location in visual space and/or to a representation of an object in the visual field, independently of their spatial location. In Posner's cueing paradigm, it is assumed that attention is moved to and then engaged at a cued location. If the target appears at an uncued location, attention first has to be disengaged from the cued location before moving to and engaging the target location. On the basis of this paradigm, we designed an experiment to measure the disengaging of attention from objects, independently of location. For this purpose we used the bistable Necker cube that can be perceived as two different object configurations, depending on the position of the front side of the cube (lower left or upper right). The subject was instructed to react when he perceived the Necker cube as a previously presented model configuration, ie a stable cube. Each condition started with a bistable cube (with equal luminance of the ribs) that gradually evolved into the model configuration, by manipulating the luminance of the ribs of the cube. Prior to this the subject was cued by a cube similar to the model in the valid condition and cued by a dissimilar cube in the invalid condition. The results showed a significant difference (F1,10=7.35; p<0.05) between the valid and invalid cue condition, indicating a significant cost for the invalid cue condition. This effect is in accord with the well-known set effect found previously with bistable figures. The difference between the valid and the invalid cue conditions will be interpreted as disengaging attention from an object. Thus, object-based components of attention can be examined by paradigms similar to Posner's paradigm for location-based attention.

scholarly journals Rhesus Monkeys Behave As If They Perceive the Duncker Illusion

2005 ◽  
Vol 17 (7) ◽  
pp. 1011-1017 ◽  
Author(s):  
A. Z. Zivotofsky ◽  
M. E. Goldberg ◽  
K. D. Powell
Keyword(s):  
Eye Movements ◽  
Visual System ◽  
Eye Movement ◽  
Smooth Pursuit ◽  
Rhesus Monkeys ◽  
Spatial Location ◽  
Pursuit Eye Movements ◽  
Retinal Motion ◽  
The World ◽  
Pattern Of Motion

The visual system uses the pattern of motion on the retina to analyze the motion of objects in the world, and the motion of the observer him/herself. Distinguishing between retinal motion evoked by movement of the retina in space and retinal motion evoked by movement of objects in the environment is computationally difficult, and the human visual system frequently misinterprets the meaning of retinal motion. In this study, we demonstrate that the visual system of the Rhesus monkey also misinterprets retinal motion. We show that monkeys erroneously report the trajectories of pursuit targets or their own pursuit eye movements during an epoch of smooth pursuit across an orthogonally moving background. Furthermore, when they make saccades to the spatial location of stimuli that flashed early in an epoch of smooth pursuit or fixation, they make large errors that appear to take into account the erroneous smooth eye movement that they report in the first experiment, and not the eye movement that they actually make.

scholarly journals Perceptual Alternation Induced by Visual Transients

Perception ◽  
10.1068/p5245 ◽  
2005 ◽  
Vol 34 (7) ◽  
pp. 803-822 ◽  
Author(s):  
Ryota Kanai ◽  
Farshad Moradi ◽  
Shinsuke Shimojo ◽  
Frans A J Verstraten
Keyword(s):  
Visual System ◽  
Apparent Motion ◽  
Binocular Rivalry ◽  
Structure From Motion ◽  
Necker Cube ◽  
Neural Mechanisms ◽  
Perceptual Alternation ◽  
Ambiguous Stimuli ◽  
Underlying Mechanisms

When our visual system is confronted with ambiguous stimuli, the perceptual interpretation spontaneously alternates between the competing incompatible interpretations. The timing of such perceptual alternations is highly stochastic and the underlying neural mechanisms are poorly understood. We show that perceptual alternations can be triggered by a transient stimulus presented nearby. The induction was tested for four types of bistable stimuli: structure-from-motion, binocular rivalry, Necker cube, and ambiguous apparent motion. While underlying mechanisms may vary among them, a transient flash induced time-locked perceptual alternations in all cases. The effect showed a dependence on the adaptation to the dominant percept prior to the presentation of a flash. These perceptual alternations show many similarities to perceptual disappearances induced by transient stimuli (Kanai and Kamitani, 2003 Journal of Cognitive Neuroscience15 664–672; Moradi and Shimojo, 2004 Vision Research44 449–460). Mechanisms linking these two transient-induced phenomena are discussed.

Author response for "The brain of the African wild dog. IV . The visual system"

2020 ◽  
Author(s):  
Samson Chengetanai ◽  
Adhil Bhagwandin ◽  
Mads F. Bertelsen ◽  
Therese Hård ◽  
Patrick R. Hof ◽  
...  
Keyword(s):  
Visual System ◽  
Author Response ◽  
African Wild Dog ◽  
Wild Dog ◽  
The Brain
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