Apparent Afterimage Size, Emmert's Law, and Oculomotor Adjustment

Perception ◽  
10.1068/p5513 ◽  
2007 ◽  
Vol 36 (8) ◽  
pp. 1214-1228 ◽  
Author(s):  
Liang Lou
Keyword(s):  
Visual Angle ◽  
Angular Size ◽  
Apparent Size ◽  
Object Size ◽  
Focal Distance ◽  
Fixed Distance ◽  
Matching Procedure ◽  
Emmert’S Law

The apparent size of an afterimage viewed from distances between 5 cm and 580 cm was matched to that of a size-adjustable stimulus at a fixed distance (20, 30, 90, and 200 cm). The experiment was conducted under normal indoor illumination with a procedure that facilitated matching for angular size. The matched size was found to increase with focal distance within 1 m and very little beyond 1 m. Similar results were obtained with an equivalent series of real stimuli subtending a constant visual angle. These findings suggest a scaling in perceived angular size in proportion to the oculomotor adjustments for accommodation and convergence. The observations of perceived angular size of the afterimage complement what Emmert's law is meant to describe (perceived object size of the afterimage), even though as the focal distance decreases it may be increasingly difficult to tease out perceived object size and perceived angular size with the matching procedure.

scholarly journals Idiosyncratic Perception: A Link Between Acuity, Perceived Position, and Apparent Size

2020 ◽  
Author(s):  
Zixuan Wang ◽  
Yuki Murai ◽  
David Whitney
Keyword(s):  
Visual Field ◽  
Visual Processing ◽  
Human Perception ◽  
Visual Space ◽  
Apparent Size ◽  
Matching Task ◽  
Object Size ◽  
Vernier Acuity ◽  
Visual Hierarchy ◽  
Different Levels

AbstractPerceiving the positions of objects is a prerequisite for most other visual and visuomotor functions, but human perception of object position varies from one individual to the next. The source of these individual differences in perceived position and their perceptual consequences are unknown. Here, we tested whether idiosyncratic biases in the underlying representation of visual space propagate across different levels of visual processing. In Experiment 1, using a position matching task, we found stable, observer-specific compressions and expansions within local regions throughout the visual field. We then measured Vernier acuity (Experiment 2) and perceived size of objects (Experiment 3) across the visual field and found that individualized spatial distortions were closely associated with variations in both visual acuity and apparent object size. Our results reveal idiosyncratic biases in perceived position and size, originating from a heterogeneous spatial resolution that carries across the visual hierarchy.

scholarly journals Idiosyncratic perception: a link between acuity, perceived position and apparent size

2020 ◽  
Vol 287 (1930) ◽  
pp. 20200825
Author(s):  
Zixuan Wang ◽  
Yuki Murai ◽  
David Whitney
Keyword(s):  
Visual Field ◽  
Visual Processing ◽  
Human Perception ◽  
Visual Space ◽  
Apparent Size ◽  
Matching Task ◽  
Object Size ◽  
Vernier Acuity ◽  
Visual Hierarchy ◽  
Different Levels

Perceiving the positions of objects is a prerequisite for most other visual and visuomotor functions, but human perception of object position varies from one individual to the next. The source of these individual differences in perceived position and their perceptual consequences are unknown. Here, we tested whether idiosyncratic biases in the underlying representation of visual space propagate across different levels of visual processing. In Experiment 1, using a position matching task, we found stable, observer-specific compressions and expansions within local regions throughout the visual field. We then measured Vernier acuity (Experiment 2) and perceived size of objects (Experiment 3) across the visual field and found that individualized spatial distortions were closely associated with variations in both visual acuity and apparent object size. Our results reveal idiosyncratic biases in perceived position and size, originating from a heterogeneous spatial resolution that carries across the visual hierarchy.

Size-Constancy in the CAVE

2007 ◽  
Vol 16 (2) ◽  
pp. 172-187 ◽  
Author(s):  
Robert V Kenyon ◽  
Daniel Sandin ◽  
Randall C Smith ◽  
Richard Pawlicki ◽  
Thomas Defanti
Keyword(s):  
Virtual Environments ◽  
Test Object ◽  
Visual Angle ◽  
Physical World ◽  
Object Size ◽  
Size Constancy ◽  
Environmental Objects ◽  
The Subject ◽  
Correct Size

The use of virtual environments (VE) for many research and commercial purposes relies on its ability to generate environments that faithfully reproduce the physical world. However, due to its limitations the VE can have a number of flaws that adversely affect its use and believability. One of the more important aspects of this problem is whether the size of an object in the VE is perceived as it would be in the physical world. One of the fundamental phenomena for correct size is size-constancy, that is, an object is perceived to be the same size regardless of its distance from the observer. This is in spite of the fact that the retinal size of the object shrinks with increasing distance from the observer. We examined size-constancy in the CAVE and found that size-constancy is a strong and dominant perception in our subject population when the test object is accompanied by surrounding environmental objects. Furthermore, size-constancy changes to a visual angle performance (i.e., object size changed with distance from the subject) when these surrounding objects are removed from the scene. As previously described for the physical world, our results suggest that it is necessary to provide surrounding objects to aid in the determination of an object's depth and to elicit size-constancy in VE. These results are discussed regarding their implications for viewing objects in projection-based VE and the environments that play a role in the perception of object size in the CAVE.

Apparent Size and Duration of a Movement After-effect

1972 ◽  
Vol 24 (3) ◽  
pp. 275-281 ◽  
Author(s):  
Claude Bonnet ◽  
Viviane Pouthas
Keyword(s):  
Apparent Size ◽  
Test Field ◽  
After Effect ◽  
The Relationship ◽  
Distance Judgments ◽  
Emmert’S Law

Four experiments were performed to study the relationship between Emmert's law and the duration of the movement after-effect (MAE). The duration of the MAE increased with increased distance of the test field; this result was shown to be produced by the correlative change in apparent size of the after image. The effect did not occur when cues for distance judgments were reduced. Reducing the duration of the MAE suppressed the variation in its duration at varying distances of the test field. Some implications for the mechanism of the MAE are discussed.

Respective Contribution of Orientation Contrast and Illusion of Self-Tilt to the Rod-And-Frame Effect

Perception ◽  
1995 ◽  
Vol 24 (6) ◽  
pp. 623-630 ◽  
Author(s):  
Corinne Cian ◽  
Dominique Esquivié ◽  
Pierre Alain Barraud ◽  
Christian Raphel
Keyword(s):  
Contrast Effect ◽  
Visual Angle ◽  
Angular Size ◽  
The Other ◽  
Frame Effect ◽  
Tilt Illusion ◽  
Orientation Contrast ◽  
Respective Contribution ◽  
Adjustment Test ◽  
Rod And Frame

The visual angle subtended by the frame seems to be an important determinant of the contribution of orientation contrast and illusion of self-tilt (ie vection) to the rod-and-frame effect. Indeed, the visuovestibular factor (which produces vection) seems to be predominant in large displays and the contrast effect in small displays. To determine how these two phenomena are combined to account for the rod-and-frame effect, independent estimates of the magnitude of each component in relation to the angular size subtended by the display were examined. Thirty-five observers were exposed to three sets of experimental situations: body-adjustment test (illusion of self-tilt only), the tilt illusion (contrast only) and the rod-and-frame test, each display subtending 7, 12, 28, and 45 deg of visual angle. Results showed that errors recorded in the three situations increased linearly with the angular size. Whatever the size of the frame, both mechanisms, contrast effect (tilt illusion) and illusory effect on self-orientation (body-adjustment test), are always present. However, rod-and-frame errors became greater at a faster rate than the other two effects as the size of the stimuli became larger. Neither one nor the other independent phenomen, nor the combined effect could fully account for the rod-and-frame effect whatever the angular size of the apparatus.

scholarly journals I. The Bakerian Lecture.— Contributions to the physiology of vision.— Part the second. On some remarkable, and hitherto unobserved, phenomena of binocular vision (continued)

1852 ◽  
Vol 142 ◽  
pp. 1-17 ◽  
Keyword(s):  
Human Physiology ◽  
Binocular Vision ◽  
Visual Angle ◽  
Apparent Size ◽  
Apparent Magnitude ◽  
The Third

In § 3. of the first part of my “Contributions to the Physiology of Vision,” published in the Philosophical Transactions for 1838, speaking of the stereoscope, I stated, “The pictures will indeed coincide when the sliding pannels are in a variety of different positions, and consequently when viewed under different inclinations of the optic axes; but there is only one position in which the binocular image will be immediately seen single, of its proper magnitude, and without fatigue to the eyes, because in this position only the ordinary relations between the magnitude of the pictures on the retina, the inclination of the optic axes, and the adaptation of the eye to distinct vision at different distances, are preserved. The alteration in the apparent magnitude of the binocular images, when these usual relations are disturbed, will be discussed in another paper of this series, with a variety of remarkable phenomena depending thereon.” In 1833, five years before the publication of the memoir just mentioned, these yet unpublished investigations were announced in the third edition of Herbert Mayo’s “Outlines of Human Physiology” in the following words:—“ Mr. W heatstone has shown, in a paper he is about to publish, that if by artificial means the usual relations which subsist between the degree of inclination of the optic axes and the visual angle which the object subtends on the retina be disturbed, some extraordinary illusions may be produced. Thus, the magnitude of the image remaining constant on the retina, its apparent size may be made to vary with every alteration of the angular inclination of the optic axes.”

scholarly journals Small or far away? Size and distance perception in the praying mantis

2016 ◽  
Vol 371 (1697) ◽  
pp. 20150262 ◽  
Author(s):  
Vivek Nityananda ◽  
Geoffrey Bissianna ◽  
Ghaith Tarawneh ◽  
Jenny Read
Keyword(s):  
Stereo Vision ◽  
Distance Perception ◽  
Angular Size ◽  
Object Size ◽  
Size Constancy ◽  
Significant Interaction Effect ◽  
Absolute Size ◽  
Praying Mantis ◽  
3D Vision ◽  
Range Finding

Stereo or ‘3D’ vision is an important but costly process seen in several evolutionarily distinct lineages including primates, birds and insects. Many selective advantages could have led to the evolution of stereo vision, including range finding, camouflage breaking and estimation of object size. In this paper, we investigate the possibility that stereo vision enables praying mantises to estimate the size of prey by using a combination of disparity cues and angular size cues. We used a recently developed insect 3D cinema paradigm to present mantises with virtual prey having differing disparity and angular size cues. We predicted that if they were able to use these cues to gauge the absolute size of objects, we should see evidence for size constancy where they would strike preferentially at prey of a particular physical size, across a range of simulated distances. We found that mantises struck most often when disparity cues implied a prey distance of 2.5 cm; increasing the implied distance caused a significant reduction in the number of strikes. We, however, found no evidence for size constancy. There was a significant interaction effect of the simulated distance and angular size on the number of strikes made by the mantis but this was not in the direction predicted by size constancy. This indicates that mantises do not use their stereo vision to estimate object size. We conclude that other selective advantages, not size constancy, have driven the evolution of stereo vision in the praying mantis. This article is part of the themed issue ‘Vision in our three-dimensional world’.

scholarly journals Dynamical, biological and anthropic consequences of equal lunar and solar angular radii

2014 ◽  
Vol 470 (2168) ◽  
pp. 20140263 ◽  
Author(s):  
Steven A. Balbus
Keyword(s):  
Selection Pressure ◽  
Angular Size ◽  
Apparent Size ◽  
Tidal Range ◽  
Temporal Modulation ◽  
Strong Selection ◽  
Tidal Forces ◽  
The Earth ◽  
Tidal Pools

The nearly equal lunar and solar angular sizes as subtended at the Earth is generally regarded as a coincidence. This is, however, an incidental consequence of the tidal forces from these bodies being comparable. Comparable magnitudes implies strong temporal modulation, as the forcing frequencies are nearly but not precisely equal. We suggest that on the basis of palaeogeographic reconstructions, in the Devonian period, when the first tetrapods appeared on land, a large tidal range would accompany these modulated tides. This would have been conducive to the formation of a network of isolated tidal pools, lending support to A. S. Romer's classic idea that the evaporation of shallow pools was an evolutionary impetus for the development of chiridian limbs in aquatic tetrapodomorphs. Romer saw this as the reason for the existence of limbs, but strong selection pressure for terrestrial navigation would have been present even if the limbs were aquatic in origin. Since even a modest difference in the Moon's angular size relative to the Sun's would lead to a qualitatively different tidal modulation, the fact that we live on a planet with a Sun and Moon of close apparent size is not entirely coincidental: it may have an anthropic basis.

Lower Pitch Is Larger, Yet Falling Pitches Shrink

2014 ◽  
Vol 61 (4) ◽  
pp. 273-284 ◽  
Author(s):  
Zohar Eitan ◽  
Asi Schupak ◽  
Alex Gotler ◽  
Lawrence E. Marks
Keyword(s):  
Visual Stimuli ◽  
Apparent Size ◽  
Object Size ◽  
Dynamic Stimuli ◽  
Visual Objects ◽  
Garner Interference ◽  
Processing Mechanisms

Experiments using diverse paradigms, including speeded discrimination, indicate that pitch and visually-perceived size interact perceptually, and that higher pitch is congruent with smaller size. While nearly all of these studies used static stimuli, here we examine the interaction of dynamic pitch and dynamic size, using Garner’s speeded discrimination paradigm. Experiment 1 examined the interaction of continuous rise/fall in pitch and increase/decrease in object size. Experiment 2 examined the interaction of static pitch and size (steady high/low pitches and large/small visual objects), using an identical procedure. Results indicate that static and dynamic auditory and visual stimuli interact in opposite ways. While for static stimuli (Experiment 2), higher pitch is congruent with smaller size (as suggested by earlier work), for dynamic stimuli (Experiment 1), ascending pitch is congruent with growing size, and descending pitch with shrinking size. In addition, while static stimuli (Experiment 2) exhibit both congruence and Garner effects, dynamic stimuli (Experiment 1) present congruence effects without Garner interference, a pattern that is not consistent with prevalent interpretations of Garner’s paradigm. Our interpretation of these results focuses on effects of within-trial changes on processing in dynamic tasks and on the association of changes in apparent size with implied changes in distance. Results suggest that static and dynamic stimuli can differ substantially in their cross-modal mappings, and may rely on different processing mechanisms.

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