Position in the Visual Field and Spatial Expansion

Perception ◽  
1983 ◽  
Vol 12 (4) ◽  
pp. 469-476 ◽  
Author(s):  
W H Norman Hotopf ◽  
Malcolm C Hibberd ◽  
Susannah A Brown
Keyword(s):  
Visual Field ◽  
Baseline Data ◽  
Horizontal Line ◽  
Spatial Expansion ◽  
Tilt Illusion ◽  
Parallel Lines ◽  
Constancy Scaling

Measurements of the tilt illusion by parallelism matches have taken as their baseline data estimates of parallelism between two lines. This is because Carpenter and Blakemore and others found in this situation that parallel lines appeared to diverge at their upper ends. It was hypothesised that this effect was due to inappropriate constancy scaling—the parallel lines being interpreted as being located in a receding plane—and that consequently it was inappropriate to take this effect into account in assessing the degree of the tilt illusion. To test the theory, a horizontal line was compared with other horizontal and vertical lines lower down in the visual field. A tendency to underestimate the length of lines lower down in the visual field was found but this varied inversely with distance from the standard. The findings were accounted for on the assumption that the occurrence of inappropriate constancy scaling depended upon prior organization by contiguity which determined whether the two lines were taken as a group or not.

scholarly journals The Flip Tilt Illusion: Visible in Peripheral Vision as Predicted by the Central-Peripheral Dichotomy

i-Perception ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 204166952093840
Author(s):  
Li Zhaoping
Keyword(s):  
Visual Field ◽  
Peripheral Vision ◽  
Receptive Fields ◽  
Top Down ◽  
Central Visual Field ◽  
Tilt Illusion ◽  
Visual Areas ◽  
Vertically Aligned ◽  
Visual Cortical ◽  
Higher Visual Areas

Consider a gray field comprising pairs of vertically aligned dots; in each pair, one dot is white the other black. When viewed in a peripheral visual field, these pairs appear horizontally aligned. By the Central-Peripheral Dichotomy, this flip tilt illusion arises because top-down feedback from higher to lower visual cortical areas is too weak or absent in the periphery to veto confounded feedforward signals from the primary visual cortex (V1). The white and black dots in each pair activate, respectively, on and off subfields of V1 neural receptive fields. However, the sub-fields’ orientations, and the preferred orientations, of the most activated neurons are orthogonal to the dot alignment. Hence, V1 reports the flip tilt to higher visual areas. Top-down feedback vetoes such misleading reports, but only in the central visual field.

scholarly journals Two-dimensional Peripheral Refraction and Retinal Image Quality in Emmetropic Children

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Weizhong Lan ◽  
Zhenghua Lin ◽  
Zhikuang Yang ◽  
Pablo Artal
Keyword(s):  
Optical Properties ◽  
Visual Field ◽  
Age Groups ◽  
Baseline Data ◽  
Two Dimensional ◽  
Future Evolution ◽  
Homogeneous Pattern ◽  
Horizontal Refraction ◽  
The Relationship

Abstract The relationship between the optical properties of the eye in the periphery and myopia development is still under debate. To further clarify this issue, we provide here baseline data of two-dimensional peripheral optics results in a group of emmetropic Chinese children. Peripheral aberrations were measured under cycloplegia by using an open-view Hartmann-Shack wavefront sensor (VPR, Voptica SL, Spain). This instrument allows to measure fast in the horizontal visual field from temporal 30° to nasal 30° every 1°. Two-dimensional (2D) maps were retrieved from a series of horizonal scans taken every 4° from 20° superior to 16° inferior covering a visual field of 60 × 36°. A relatively homogeneous pattern of the 2D relative peripheral refraction was found across all these emmetropic subjects. Using cluster analysis followed by manual visual refinement, the 2D maps were identified to fit into four categories. More than 70% of the subjects showed a nearly flat horizontal refraction with a slightly myopic shift in the superior retina. Peripheral astigmatism was quite constant across subjects and similar to that expected theoretically. Peripheral aberrations were also similar to those in the fovea for a large retinal area. These baseline data would offer an important reference to compare with the future evolution with time, as well as with other refractive or age groups of subjects, to better understand the role of peripheral optical properties in myopia development.

Combined Influences of Gravitoinertial Force Level and Visual Field Pitch on Visually Perceived Eye Level

1997 ◽  
Vol 7 (5) ◽  
pp. 381-392
Author(s):  
Paul DiZio ◽  
Wenxun Li ◽  
James R. Lackner ◽  
Leonard Matin
Keyword(s):  
Visual Field ◽  
Visual Target ◽  
Weighted Average ◽  
Total Darkness ◽  
Force Level ◽  
Parallel Lines ◽  
Quantitative Characteristics ◽  
Gravitoinertial Force ◽  
The Subject ◽  
Vector Sum

Psychophysical measurements of the level at which observers set a small visual target so as to appear at eye level (VPEL) were made on 13 subjects in 1.0 g and 1.5 g environments in the Graybiel Laboratory rotating room while they viewed a pitched visual field or while in total darkness. The gravitoinertial force was parallel to the z-axis of the head and body during the measurements. The visual field consisted of two 58° high, luminous, pitched-from-vertical, bilaterally symmetric, parallel lines, viewed in otherwise total darkness. The lines were horizontally separated by 53° and presented at each of 7 angles of pitch ranging from 30° with the top of the visual field turned away from the subject (top backward) to 30° with the top turned toward the subject (top forward). At 1.5 g, VPEL changed linearly with the pitch of the 2-line stimulus and was depressed with top hackward pitch and elevated with top forward pitch as had been reported previously at 1.0 g (1.2): however, the slopes of the VPEL-vs-pitch functions at 1.0 g and 1.5 g were indistinguishable. As reported previously also (3,4), the VPEL in darkness was considerably lower at 1.5 g than at 1.0 g: however, although the y-intercept of the VPEL-vs-pitch function in the presence of the 2-line visual field (visual field erect) was also lower at 1.5 g than at 1.0 g as it was in darkness, the G-related difference was significantly attenuated by the presence of the visual field. The quantitative characteristics of the results are consistent with a model in which VPEL is treated as a consequence of an algebraic weighted average or a vector sum of visual and nonvisual influences although the two combining rules lead to fits that are equally good.

Room Tilt Illusion as a Manifestation of Peripheral Vestibular Disorders

2003 ◽  
Vol 112 (7) ◽  
pp. 600-605 ◽  
Author(s):  
Didier-David Malis ◽  
Jean-Philippe Guyot
Keyword(s):  
Visual Field ◽  
Brain Stem ◽  
Frontal Plane ◽  
Cortical Lesions ◽  
Vestibular Disorders ◽  
Review Of The Literature ◽  
Tilt Illusion ◽  
Proprioceptive Inputs ◽  
Peripheral Origin ◽  
Vestibular Pathways

Room tilt illusion is a subjective distortion of verticality with transient paradoxical rotation of the visual field, usually in the frontal plane. It might result from dysfunction of the vestibular pathways with subsequent contradictory vestibular, visual, and proprioceptive inputs and erroneous cortical integration. It has already been described in association with brain stem and cortical lesions, but reports of cases of peripheral origin are scarce. We report here 23 cases of room tilt illusion, all but 2 occurring in patients with either vestibular peripheral abnormalities or normal assessment findings. A review of the literature is presented, as well as a hypothesis addressing this phenomenon.

scholarly journals Stochastic re-calibration: contextual effects on perceived tilt

2006 ◽  
Vol 273 (1601) ◽  
pp. 2681-2686 ◽  
Author(s):  
Joshua A Solomon ◽  
Michael J Morgan
Keyword(s):  
Visual Field ◽  
Visual System ◽  
Lateral Inhibition ◽  
Human Visual System ◽  
Contextual Effects ◽  
Letter Recognition ◽  
Tilt Illusion ◽  
Reference Orientation ◽  
The Difference

The human visual system exaggerates the difference between the tilts of adjacent lines or grating patches. In addition to this tilt illusion, we found that oblique flanks reduced acuity for small changes of tilt in the centre of the visual field. However, no flanks—regardless of their tilts—decreased sensitivity to contrast. Thus, the foveal tilt illusion should not be attributed to orientation-selective lateral inhibition. Nor is it similar to conventional crowding, which typically does not impair letter recognition in the fovea. Our observers behaved as though the reference orientation (horizontal) had a small tilt in the direction of the flanks. We suggest that the extent of this re-calibration varies randomly over trials, and we demonstrate that this stochastic re-calibration can explain flank-induced acuity loss in the fovea.

Categorical versus Coordinate Spatial Processing: Effects of Blurring and Hemispheric Asymmetry

1994 ◽  
Vol 6 (2) ◽  
pp. 156-164 ◽  
Author(s):  
Elizabeth L. Cowin ◽  
Joseph B. Hellige
Keyword(s):  
Visual Field ◽  
Visual Information ◽  
Right Hemisphere ◽  
Visual Fields ◽  
Spatial Processing ◽  
Right Visual Field ◽  
Horizontal Line ◽  
Significant Difference ◽  
Categorical Task ◽  
The Right

The present experiment examined the effects of dioptric blurring on the performance of two different spatial processing tasks using the same visual stimuli. One task (the above/below, categorical task) required subjects to indicate whether a dot was above or below a horizontal line. The other task (the coordinate, near/far task) required subjects to indicate whether the dot was within 3 mm of the line. For both tasks, the stimuli on each trial were presented to either the right visual field and left hemisphere (RVF/LH) or the left Visual field and right hemisphere (LVF/RH). For the above/below task, dioptric blurring consistently increased reaction time (RT) and did so equally on LVF/RH and RVF/LH trials. Furthermore, there was no significant difference between the two visual fields for either clear or blurred stimuli. For the near/far task, dioptric blurring had no consistent effect on either RT or error rate for either visual field. On an initial block of trials, however, there were significantly fewer errors on LVF/RH than on RVF/LH trials, with the LVF/RH advantage being independent of whether the stimuli were clear or blurred. This initial LVF/RH advantage disappeared quickly with practice, regardless of whether the stimuli were clear or blurred. This pattern of results suggests that for both cerebral hemispheres, somewhat different aspects of visual information are relevant for categorical versus coordinate spatial processing and that the right hemisphere is superior to the left for coordinate (but not categorical) spatial processing.

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