Tests of the Dipole Model of Perceived Movement in Apertures

Perception ◽  
1993 ◽  
Vol 22 (9) ◽  
pp. 1099-1110 ◽  
Author(s):  
Roderick P Power
Keyword(s):  
Apparent Movement ◽  
Motion Aftereffect ◽  
Dipole Model ◽  
The Other ◽  
Test Spot ◽  
Clear Vision ◽  
Horizontal Grating

Power and Moulden (1993) have proposed a dipole model to account for the apparent movement of gratings in apertures. This includes movement orthogonal to the orientation of the grating, and the barber pole illusion: the illusion that a grating drifting diagonally across a narrow aperture appears to be moving along it. The essence of the model is that movement is signalled by a large number of dipoles, of many orientations and lengths. These dipoles respond if, and only if, one end is stimulated, and then the other. Three experiments intended to test predictions from the model are reported here. In each case a horizontal grating drifted across an aperture and subjects fixated outside the aperture. In experiment 1 subjects fixated just above or below the aperture, and reported the motion aftereffect (MAE) shown by a set of test spots. As predicted by the model, the spots further from the fixation point showed a strong MAE. Experiment 2 combined both viewing conditions of experiment 1, so that test spots above and below the fixation point were viewed simultaneously. The predictions were confirmed, since test spots further from the fixation point exhibited a stronger MAE than test spots closer to the fixation point. In experiment 3 the fixation point in all conditions was below the aperture, and, as predicted, the MAE of a spot near the bottom of the aperture was diagonally upward, although stimulation was horizontal. Again, as predicted, the MAE of a spot in the middle of the aperture appeared to move horizontally. Finally, it was predicted that a test spot at the top of the aperture would appear to move diagonally downwards, but subjects were unable to report unequivocally the direction of motion, since the MAE was occurring too far from the fovea for clear vision. Overall, then, the predictions from the model were confirmed, although there are associated phenomena the model cannot as yet account for.

The Role of the Marketplace in the Post-Covid-19 City of Tomorrow

BUILDER ◽  
2021 ◽  
Vol 289 (8) ◽  
pp. 56-63
Author(s):  
Bartłomiej Buława
Keyword(s):  
Urban Environment ◽  
Development Strategy ◽  
Small Towns ◽  
The Other ◽  
Social Expectations ◽  
Unique Character ◽  
Clear Vision ◽  
Distinct Character ◽  
Effective Development

The role of the marketplace in a city changes from decade to decade. They lose their significance or followings clients’ demands they expand their range of services, creating a unique character and brand. These are places of culture-creating potential, not only of fulfilling basic shopping needs. Six marketplaces of distinct character and impact on the community have been analyzed in order to present their development potential as well as occurring problems. The challenge for many marketplaces, especially smaller ones and those in small towns is the effective development strategy, taking into account current social expectations and consumer trends. When left without a clear vision of the future they often succumb to the competition. On the other hand, when properly developed and transformed they influence the identity of a district or city increasing its multi-functionality. Marketplaces may play a significant role in social integration processes and revitalization of the urban environment in the post-Covid-19 city of tomorrow.

Optimal Camera Placement in a Virtual Environment

2021 ◽  
pp. 247-260
Author(s):  
Hocine Chebi
Keyword(s):  
Real Time ◽  
Virtual Environment ◽  
The Other ◽  
New Method ◽  
Camera Placement ◽  
Virtual Camera ◽  
Clear Vision ◽  
Transmission Of Information ◽  
The One ◽  
Visual Properties

Camera placement in a virtual environment consists of positioning and orienting a 3D virtual camera so as to respect a set of visual or cinematographic properties defined by the user. Carrying out this task is difficult in practice. Indeed, the user has a clear vision of the result he wants to obtain in terms of the arrangement of the objects in the image. In this chapter, the authors identify three areas of research that are relatively little covered by the literature dedicated to camera placement and which nevertheless appear essential. On the one hand, existing approaches offer little flexibility in both solving and describing a problem in terms of visual properties, especially when it has no solution. They propose a flexible solution method which computes the set of solutions, maximizing the satisfaction of the properties of the problem, whether it is over constrained or not. On the other hand, the existing methods calculate only one solution, even when the problem has several classes of equivalent solutions in terms of satisfaction of properties. They introduce the method of semantic volumes which computes the set of classes of semantically equivalent solutions and proposes a representative of each of them to the user. Finally, the problem of occlusion, although essential in the transmission of information, is little addressed by the community. Consequently, they present a new method of taking into account occlusion in dynamic real-time environments.

scholarly journals Hadronic properties of the photon

2019 ◽  
Vol 204 ◽  
pp. 05012
Author(s):  
Sergey Gevorkyan
Keyword(s):  
High Energy ◽  
Dipole Model ◽  
The Other ◽  
Dominance Model ◽  
Color Transparency ◽  
Vector Dominance ◽  
Color Dipole ◽  
The Impact ◽  
Color Dipole Model ◽  
Hadronic Component

Currently it is no doubt that high energy photons (real or virtual) have a hadronic component leading to photon shadowing in its interaction with nuclei. We shortly consider the difficulties appeared in the models like vector dominance model (VDM) and stress that these problems can be solved in a color dipole model inspired by Quantum Chromodynamics (QCD). From the other hand, the color dipole model allows one to investigate the impact of vector meson polarization on their interaction with nucleons and nuclei, the challenge which is crucial for studying, for instance, such a fundamental effect as color transparency.

Subjective Velocity Estimates of Apparent Movement following Visual Stimulation

1971 ◽  
Vol 33 (3_suppl) ◽  
pp. 1029-1030
Author(s):  
John K. Collins
Keyword(s):  
Visual Motion ◽  
Intertrial Interval ◽  
Visual Stimulation ◽  
Apparent Movement ◽  
Motion Aftereffect ◽  
Apparent Velocity ◽  
Stationary Target ◽  
Apparent Rotation ◽  
The Mean

Tracking the apparent movement of a stationary target following prior stimulation by rotation was used to estimate the subjective velocity of the visual motion aftereffect. 10 Ss were given 4 trials each with the apparent velocity averaged over a 10-sec. period following 60 sec. stimulation. The intertrial interval was 5 min. The mean apparent rotation was 1.5° per sec. with SD of 1.6°.

The psychophysical periphery effect crosses the vertical meridian

2001 ◽  
Vol 18 (4) ◽  
pp. 657-661
Author(s):  
THOMAS KUYK ◽  
DIANA NICULESCU
Keyword(s):  
Neural Mechanism ◽  
Spot Test ◽  
The Other ◽  
Vertical Meridian ◽  
Peripheral Stimulation ◽  
Test Spot ◽  
Cat Retina ◽  
Close Proximity ◽  
Test Thresholds ◽  
Periphery Effect

This study measured the periphery effect and compared its magnitude when the peripheral stimulation was on the same or opposite side of the vertical meridian as the test spot. Test thresholds for a 1.5-deg diameter, 8-ms spot located 1.75 deg to one side of the vertical meridian were elevated by approximately 0.125 log units when a 0.25 cycles/deg (cpd) counterphased grating was presented at a similar eccentric offset on the other side of the vertical meridian. The periphery effect disappeared when the test spot was moved outward to 8-deg eccentricity. When the grating and test were presented on the same side of the vertical meridian, test thresholds at both retinal locations were elevated by the same amount, 0.2 log units. Consistent with the physiology in cat retina, the periphery effect in humans also crosses over the vertical meridian. However, the effect is small and the test spot must be in close proximity to the vertical meridian for it to be observed. Also, the crossover periphery effect is reduced in magnitude by 37.5% compared to when the grating and test are presented on the same side of the vertical meridian. This suggests there may be a difference in how the underlying neural mechanism that transmits the periphery effect signal laterally is organized for sending the periphery effect signal across the vertical meridian as compared to within a retinal hemifield.

Motion Aftereffects of Wagon Wheels: Motion Aftereffects Follow Apparent Rather Than Real Movement

1994 ◽  
Vol 79 (1) ◽  
pp. 131-140
Author(s):  
Roderick P. Power
Keyword(s):  
Apparent Movement ◽  
Motion Aftereffect ◽  
Flickering Light ◽  
Wagon Wheel ◽  
True Motion ◽  
Apparent Direction ◽  
Illusory Movement ◽  
Motion Aftereffects ◽  
Direction Opposite ◽  
True Direction

Power and Moulden have proposed a model which accounts for the movement of gratings in apertures including the barber pole illusion. It predicts the direction of motion aftereffects which follow from perceived veridical motion and the direction of these aftereffects which follow from the illusory movement experienced during the barber pole illusion. At a perceptual level, the model predicts motion aftereffects will follow direction of apparent movement rather than veridical direction. Four experiments tested this prediction. In Exp. 1 a spiral was viewed under flickering light so it appeared to be moving in the direction opposite to true motion, and the aftereffect was opposite to the apparent direction. In Exp. 2 the spiral was viewed through a narrow aperture so that it was effectively a grating appearing to move in the opposite direction to veridical motion. Again, the motion aftereffect was opposite to the apparent rather than true direction of rotation. In Exp. 3 a sectored disc was used, and similar results were obtained. In Exp. 4 the sectored disc was videotaped so that it appeared to be rotating in the direction opposite to true motion. The after motion to this “wagon wheel” effect was opposite to its apparent direction of rotation on the screen. In all experiments the predictions were confirmed, thereby confirming the general principle that motion aftereffecrs follow apparent rather than real direction of movemenr.

On Interocular Transfer of Motion Aftereffects

Perception ◽  
1993 ◽  
Vol 22 (11) ◽  
pp. 1365-1380 ◽  
Author(s):  
Nicholas J Wade ◽  
Michael T Swanston ◽  
Charles M M de Weert
Keyword(s):  
Interocular Transfer ◽  
Motion Aftereffect ◽  
Dark Field ◽  
The Other ◽  
Retinal Motion ◽  
Black Field ◽  
History Of ◽  
Contralateral Eye ◽  
Motion Aftereffects ◽  
Motion Detectors

A brief history of quantitative assessments of interocular transfer (IOT) of the motion aftereffect (MAE) is presented. Recent research indicates that the MAE occurs as a consequence of adapting detectors for relative rather than retinal motion. When gratings above and below a stationary, fixated grating are moved in an otherwise dark field the central, retinally stationary grating appears to move in the opposite direction; when tested with stationary gratings an MAE is almost entirely confined to the central grating. The IOT of such an MAE was measured in experiment 1: the display was presented to one eye with a black field in the other. The IOT was about 30% of the monocular MAE. Similar values were found in experiment 2, in which the contralateral eye received an equivalent central stationary grating during adaptation and test. The dichoptic interaction of the processes involved in the MAE was examined by presenting the central gratings to both eyes and a single flanking grating above in one eye and below in the other (experiment 3). The MAE was tested with either the same or the contralateral pairing. Oppositely directed MAEs were found for the central and flanking gratings, but they were confined mainly to the conditions in which the configurations presented during adaptation were present in the same eyes during test. In experiment 4, the surround MAEs were compared after adaptation with two moving gratings in one eye or with a similar dichoptic configuration, and they were of similar duration. In a final experiment the MAE was tested either monocularly or binocularly after alternating adaptation of the left and right eyes and was found to be of the same duration. It is concluded that the MAE is a consequence of adapting relational-motion detectors, which are either monocular or of the binocular OR class.

Measuring Attention Using Induced Motion

Perception ◽  
1989 ◽  
Vol 18 (3) ◽  
pp. 303-320 ◽  
Author(s):  
Walter C Gogel ◽  
Thomas J Sharkey
Keyword(s):  
Apparent Motion ◽  
Test Object ◽  
The Other ◽  
Horizontal Motion ◽  
Involuntary Attention ◽  
Frontoparallel Plane ◽  
Physical Motion ◽  
Test Spot ◽  
Induced Motion

Attention was measured by means of its effect upon induced motion. Perceived horizontal motion was induced in a vertically moving test spot by the physical horizontal motion of inducing objects. All stimuli were in a frontoparallel plane. The induced motion vectored with the physical motion to produce a clockwise or counterclockwise tilt in the apparent path of motion of the test spot. Either a single inducing object or two inducing objects moving in opposite directions were used. Twelve observers were instructed to attend to or to ignore the single inducing object while fixating the test object and, when the two opposing inducing objects were present, to attend to one inducing object while ignoring the other. Tracking of the test spot was visually monitored. The tilt of the path of apparent motion of the test spot was measured by tactile adjustment of a comparison rod. It was found that the measured tilt was substantially larger when the single inducing object was attended rather than ignored. For the two inducing objects, attending to one while ignoring the other clearly increased the effectiveness of the attended inducing object. The results are analyzed in terms of the distinction between voluntary and involuntary attention. The advantages of measuring attention by its effect on induced motion as compared with the use of a precueing procedure, and a hypothesis regarding the role of attention in modifying perceived spatial characteristics are discussed.

Britain, Russia, and the Revival of “Entente Diplomacy”: 1934

1967 ◽  
Vol 6 (2) ◽  
pp. 99-123 ◽  
Author(s):  
Donald N. Lammers
Keyword(s):  
Sustained Attention ◽  
The Other ◽  
Clear Vision ◽  
Triple Entente ◽  
Almost All ◽  
European Diplomacy

In the annals of European diplomacy the year 1934 belongs to Louis Barthou. Coming to office in the Doumergue ministry formed in the wake of the bloody rioting of February, Barthou brought to the Quai d'Orsay a combination of clear vision, steady purpose, and nicely judged audacity which gave to French policy in the 1930s almost all the little luster it can fairly claim. Put shortly, Barthou's plan was to safeguard the French against the menace of German nationalism by reconstituting as nearly as possible the Triple Entente of prewar years. The spirit which animated him may be traced to his former mentor, Raymond Poincaré, but the design was his own, and the approaches to Britain and Russia which it entailed demanded far more insight and finesse than Poincaré had showed in the years of his postwar premiership.Historians, faced by the whole horrific record of the Hitler regime, have tended to treat Barthou's effort approvingly despite its eventual ill success. The accounts they have produced so far, however, have been focussed on Franco-Soviet or Anglo-French relations. The Anglo-Soviet side of the diplomatic triangle, never a match for the other two in prominence, has not come in for much sustained attention. Yet relations between Britain and Russia, developing in the context powerfully shaped by Barthou's initiative, were never more cordial and hopeful than over the years 1934-35; in view of the fateful consequences of their later deterioration, it is surely worth inquiring closely into the circumstances and implications of their original improvement.

Fluctuations in Perceptual Organization and Orientation and Perception of Apparent Movement

1968 ◽  
Vol 27 (2) ◽  
pp. 368-370 ◽  
Author(s):  
Roy B. Mefferd
Keyword(s):  
Perceptual Organization ◽  
Necker Cube ◽  
Frontal Plane ◽  
Apparent Movement ◽  
The Other ◽  
Central Unit ◽  
Perceptual Unit ◽  
Central Section ◽  
Apparent Position

Three main percepts of a static flat stimulus were reported, one veridical and two with apparent internal depth but which varied in the degree of perceptual organization. In one of these, the entire stimulus formed a single perceptual unit which “reversed” perspective as a unit in a fashion similar to a Necker cube. This percept elicited no reports of apparent movement, but the other percept did. In the latter, the offset central section formed one perceptual unit that was blurred, and the sharp, distinct parts on either side of it formed another unit. The central unit underwent figure-ground reversals, while the adjacent slats of both elements “changed” orientation independently. The changes in apparent position accompanying the latter fluctuations were often perceived as being due to movement of the central section in the frontal plane.

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