scholarly journals Illusion decrement and transfer of illusion decrement in obtuse- and acute-angle variants of the Poggendorff illusion

1990 ◽  
Vol 48 (5) ◽  
pp. 467-476 ◽  
Author(s):  
John Predebon
Keyword(s):  
Poggendorff Illusion ◽  
Acute Angle ◽  
Illusion Decrement

Are the Obtuse Angles the Key Components of the Poggendorff Illusion?

Perception ◽  
1981 ◽  
Vol 10 (2) ◽  
pp. 165-172 ◽  
Author(s):  
Peter Wenderoth ◽  
Michael Johnson
Keyword(s):  
Poggendorff Illusion ◽  
Acute Angle ◽  
Obtuse Angle ◽  
Negative Effects ◽  
Linear Summation ◽  
Displacement Effect ◽  
Positive Effects ◽  
Poggendorff Figure

An experiment is reported which confirms and extends a previous finding that amputations of the Poggendorff figure do not necessarily result in large positive effects with obtuse-angle stimuli, and small or even negative effects with acute-angle stimuli. Indeed, the acute-angle effects found were significantly greater than the obtuse-angle effects, and the full Poggendorff error was not explicable in terms of the linear summation of the component-angle effects. An ‘alignment displacement effect’ reported earlier by Hotopf and Obonai was shown to occur, but could not be an important component of the Poggendorff illusion.

Acute Angles and the Poggendorff Illusion

1972 ◽  
Vol 24 (2) ◽  
pp. 169-174 ◽  
Author(s):  
A. W. Pressey ◽  
O. Sweeney
Keyword(s):  
Poggendorff Illusion ◽  
Test Line ◽  
Acute Angle ◽  
Highly Effective ◽  
Formed Part ◽  
Apparent Orientation

Burns and Pritchard's (1971) explanation of the Poggendorff illusion is criticized. An experiment was designed to determine whether the acute angle plays any role in the perception of the illusion. The results showed that (i) an inducing line which crossed a test-line was highly effective in altering the apparent orientation of the test line, (ii) an inducing line forming an acute angle with a test-line had a small effect in changing the apparent orientation of the test-line, and (iii) an acute angle which formed part of the Poggendorff configuration produced an effect opposite to that predicted by the view that acute angles are perceptually enlarged.

The Poggendorff Illusion: An Illusion of Linear Extent?

Perception ◽  
1981 ◽  
Vol 10 (2) ◽  
pp. 155-164 ◽  
Author(s):  
Suzanne Greist-Bousquet ◽  
Harvey R Schiffman
Keyword(s):  
Poggendorff Illusion ◽  
Acute Angle ◽  
Obtuse Angle ◽  
Spatial Distortion ◽  
Standard Version ◽  
Lyer Illusion ◽  
Poggendorff Figure ◽  
Linear Extent ◽  
Poggendorff Effect ◽  
Intersection Points

In the standard version of the Poggendorff figure a transversal intersects two parallel verticals and the segment of the transversal between the two intersection points, A and B, is not shown. The two portions of the transversal outside the parallels then seem to be misaligned. Besides this illusion of direction, there is also an illusion of size, the distance AB being underestimated in the standard figure. The influence of configural components in determining this spatial distortion of the Poggendorff figure was examined by having subjects reproduce the inner oblique (at 45°) extent AB in variations of the figure. This distance was found to be underestimated in Poggendorff variations which contained parallel (vertical) components that formed an acute angle with AB; and the underestimation increased as the number of these components present in the figure increased. The distance AB was found not to be significantly distorted in figures which contained only those parallel (vertical) components that formed an obtuse angle with AB, yet their presence in the figure tended to counteract the underestimation. When the transversals were omitted, the underestimation was found to increase. The findings are interpreted in support of an explanation that reduces the Poggendorff effect to those factors which mediate the Müller-Lyer illusion.

Crack divergence phenomena in tempered glass

2020 ◽  
Vol 13 (3) ◽  
pp. 115-129
Author(s):  
Shin’ichi Aratani
Keyword(s):  
Optimal Design ◽  
High Speed ◽  
Glass Plate ◽  
Acute Angle ◽  
Divergence Angle ◽  
High Speed Photography ◽  
Tempered Glass ◽  
Thick Glass

High speed photography using the Cranz-Schardin camera was performed to study the crack divergence and divergence angle in thermally tempered glass. A tempered 3.5 mm thick glass plate was used as a specimen. It was shown that two types of bifurcation and branching existed as the crack divergence. The divergence angle was smaller than the value calculated from the principle of optimal design and showed an acute angle.

EFFECTS OF FREE INSPECTION AND FIXATION ON THE MAGNITUDE OF THE POGGENDORFF ILLUSION

1966 ◽  
Vol 23 (2) ◽  
pp. 663-670 ◽  
Author(s):  
STANLEY NOVAK
Keyword(s):  
Poggendorff Illusion

Effect of postural changes on intraocular pressure in patients with acute angle-closure glaucoma in Indian population

2020 ◽  
Vol 3 ◽  
pp. 2
Author(s):  
Sanjay Mishra ◽  
Ashok Kumar
Keyword(s):  
Intraocular Pressure ◽  
Acute Angle ◽  
Angle Closure Glaucoma ◽  
Angle Closure ◽  
Sitting Position ◽  
Rebound Tonometer ◽  
Antiglaucoma Medication ◽  
Primary Angle Closure Glaucoma ◽  
Postural Changes ◽  
Healthy Control

Objective: The objective of the study was to compare the posture-induced intraocular pressure (IOP) changes in primary angle-closure glaucoma (PACG) with or without glaucoma medications, and healthy control eyes with normal IOPs in Indian subjects. Materials and Methods: The IOP was measured in the sitting position and the supine position after 10, 20, and 30 min with a rebound tonometer. Results: Twenty-five patients with PACG and 30 controls with normal IOPs were studied. The IOP in the sitting position measured with the rebound tonometer was 13.8 + 3.2 mm Hg in eyes with PAC, and 12.9 + 2.9 mm Hg in eyes with normal IOPs. The IOP increased to 14.4 mm Hg, 16.8 mm Hg, and 18.9 mm Hg at 10 min, 20 min, and 30 min in PACG subjects. In normal age-matched controls, the IOP increased to 13.4 mm Hg, 14.9 mm Hg, and 17.8 mm Hg at 10 min, 20 min, and 30 min, respectively, but none of these differences were significant (P = 0.09; P = 0.08, P = 0.08). The mean postural IOP change from baseline was also not significant between the two groups. Only three patients were on single antiglaucoma medication with well-controlled IOP in the PACG group. Conclusions: Postural IOP changes are comparable among eyes with PACG with and without glaucoma medications, and control eyes.

Glaucoma at a tertiary referral eye hospital in Nepal

1970 ◽  
Vol 3 (2) ◽  
pp. 123-127
Author(s):  
I Paudyal ◽  
SS Thapa ◽  
G Paudyal ◽  
R Gurung ◽  
S Ruit
Keyword(s):  
Primary Open Angle Glaucoma ◽  
Open Angle Glaucoma ◽  
Applanation Tonometry ◽  
Acute Angle ◽  
Secondary Glaucoma ◽  
Angle Closure Glaucoma ◽  
Field Analysis ◽  
Angle Closure ◽  
Open Angle ◽  
Tertiary Referral

Background: Glaucoma is an important cause of blindness. Objective: To report the distribution of various types of glaucoma among patients presenting to a tertiary eye hospital in Nepal. Materials and methods: All new patients visiting the hospital between March 2007 and February 2008 underwent a comprehensive eye examination. Whenever glaucoma was suspected, patients were referred to fellowship-trained glaucoma specialists. Patients received a comprehensive glaucoma workup including applanation tonometry, stereoscopic examination of the optic nerve head performed by the glaucoma specialists, and a Humphrey visual field analysis (SITA 24 - 2). Results: 447 patients were newly diagnosed with glaucoma. 171 (38.2 %) patients had primary open-angle glaucoma (POAG), while 143 (32 %) had primary angle-closure glaucoma (PACG). The average age of presentation of patients with POAG was 65.78 ± 9.1 years, while the average age for PACG patients was 54.6 ±12.8 years. 30 (21 %) patients with PACG had acute angle-closure on presentation, while 113 (79 %) had chronic angle closure glaucoma. 107 (75 %) of these patients with PACG had visual acuity of less than 3/60 (20/ 400) in the worse eye at presentation. The most common form of secondary glaucoma was lens-induced (5.3 %), followed by neovascular (3.2 %) and uveitic glaucoma (3.2 %). Conclusion: The most common glaucoma seen in a tertiary referral eye hospital of Nepal is primary open-angle glaucoma. Among the angle-closure glaucoma, chronic angle-closure is the most common. Lens-induced glaucoma is still the commonest cause of secondary glaucoma. Keywords: glaucoma, open-angle, angle-closure, lens-induced DOI: http://dx.doi.org/10.3126/nepjoph.v3i2.5263 Nepal J Ophthalmol 2011; 3(2): 123-127

Quantitative Study of the Poggendorff Illusion in School Children upon Presentation of 3D Images

2020 ◽  
Vol 46 (4) ◽  
pp. 366-372
Author(s):  
S. I. Rychkova ◽  
R. I. Sandimirov ◽  
L. V. Kosobutskaya
Keyword(s):  
Quantitative Study ◽  
School Children ◽  
Poggendorff Illusion ◽  
3D Images

scholarly journals Simultaneous and Bilateral Non-Arteritic Anterior Ischaemic Optic Neuropathy and Acute Angle-Closure

2021 ◽  
pp. 1-4
Author(s):  
Gerardo Esteban Cepeda-Ortegon ◽  
Alan Baltazar Treviño-Herrera ◽  
Abraham Olvera-Barrios ◽  
Alejandro Martínez-López-Portillo ◽  
Jesús Mohamed-Hamsho ◽  
...  
Keyword(s):  
Optic Neuropathy ◽  
Acute Angle ◽  
Angle Closure ◽  
Ischaemic Optic Neuropathy ◽  
Anterior Ischaemic Optic Neuropathy ◽  
Acute Angle Closure
Sign in / Sign up

Export Citation Format

Share Document