scholarly journals Interference in Tilt-Illusion stimuli: A simple illustration

2020 ◽  
Author(s):  
Bernt Skottun
Keyword(s):  
Visual System ◽  
Relative Phase ◽  
Tilt Illusion ◽  
System P ◽  
Three Phase ◽  
Amplitude Spectra ◽  
Phase Differences

The relevance of relative phase for addition of amplitude spectra was demonstrated by comparing theeffect of three phase differences, 0, π/2 = 90 degrees, and π = 180 degrees, with two theoretical amplitudespectra displaced relative to each other as they would if they represented stimuli of different orientations.Differences in phase cause the amplitudes in the combined stimulus to be reduced relative to the sum ofamplitudes in the two spectra. Because the reductions are most pronounced where the spectra overlap, inthe case of partially overlapping spectra this may cause the two spectra to be effectively shifted away fromeach other. In the case where the spectra belong to stimuli of different orientations such shifts may cause theapparent angle between two stimuli to increase. This may be consistent with the Tilt Illusion. In which caseit may be possible to account for this illusion based on the stimuli without implicating the visual system.

scholarly journals Is the Tilt-Illusion in the stimuli?

2018 ◽  
Author(s):  
Bernt Skottun
Keyword(s):  
Visual System ◽  
Present Report ◽  
Visual Stimuli ◽  
Orientation Tuning ◽  
Tilt Illusion ◽  
Amplitude Spectra

Interference between visual stimuli has been assessed mainly in regard to how such interactions mayreduce stimulus power. The question of if, or to what extent, interference may change stimuli in other wayshas been largely ignored. The present report asks if interference may alter the amplitude spectra of elongatedcontours so as cause their perceived orientations to be changed. Computations indicate that for two stimulidiffering in orientation by between 5 and 40 degrees interference is largest for orientations between the peakorientations of the two stimuli which may cause their orientation tuning functions to be ”pushed” apart.Since interference takes place in the stimuli and is independent of vision and the visual system it is possible,therefore, for the physics of stimuli to cause illusory tilt.

Friedel'S law breakdown and interpretation of stacking fault images in tetrahedral semiconductors

1987 ◽  
Vol 45 ◽  
pp. 318-319
Author(s):  
Rob. W. Glaisher ◽  
A.E.C. Spargo
Keyword(s):  
Relative Phase ◽  
Point Group ◽  
Binary Compound ◽  
Stacking Fault ◽  
Fold Axis ◽  
Atom Pair ◽  
Tetrahedral Semiconductors ◽  
Group Symmetries ◽  
Thin Crystal ◽  
Phase Differences

Images of <11> oriented crystals with diamond structure (i.e. C,Si,Ge) are dominated by white spot contrast which, depending on thickness and defocus, can correspond to either atom-pair columns or tunnel sites. Olsen and Spence have demonstrated a method for identifying the correspondence which involves the assumed structure of a stacking fault and the preservation of point-group symmetries by correctly aligned and stigmated images. For an intrinsic stacking fault, a two-fold axis lies on a row of atoms (not tunnels) and the contrast (black/white) of the atoms is that of the {111} fringe containing the two-fold axis. The breakdown of Friedel's law renders this technique unsuitable for the related, but non-centrosymmetric binary compound sphalerite materials (e.g. GaAs, InP, CdTe). Under dynamical scattering conditions, Bijvoet related reflections (e.g. (111)/(111)) rapidly acquire relative phase differences deviating markedly from thin-crystal (kinematic) values, which alter the apparent location of the symmetry elements needed to identify the defect.

scholarly journals Combined Reduced Phase Dual-Directional Illumination Digital Holography and Speckle Displacements for Shape Measurement

2019 ◽  
Vol 2019 ◽  
pp. 1-6
Author(s):  
Davood Khodadad
Keyword(s):  
Phase Difference ◽  
Digital Holography ◽  
Relative Phase ◽  
Groove Depth ◽  
Phase Unwrapping ◽  
Shape Measurement ◽  
Phase Ambiguity ◽  
Holographic Method ◽  
Height Range ◽  
Phase Differences

We present a digital holographic method to increase height range measurement with a reduced phase ambiguity using a dual-directional illumination. Small changes in the angle of incident illumination introduce phase differences between the recorded complex fields. We decrease relative phase difference between the recorded complex fields 279 and 139 times by changing the angle of incident 0.5° and 1°, respectively. A two cent Euro coin edge groove is used to measure the shape. The groove depth is measured as ≈300  μm. Further, numerical refocusing and analysis of speckle displacements in two different planes are used to measure the depth without a use of phase unwrapping process.

A superamphiphobic surface with a hydrogen peroxide-triggered switch to antithetic fluid repellence in a liquid–liquid–air three-phase fluid system

2020 ◽  
Vol 56 (31) ◽  
pp. 4312-4315
Author(s):  
Yihan Sun ◽  
Jinxia Huang ◽  
Zhiguang Guo
Keyword(s):  
Hydrogen Peroxide ◽  
The Other ◽  
Fluid System ◽  
System P ◽  
Arbitrary Phase ◽  
Three Phase ◽  
Air System ◽  
Two Phases ◽  
Phase Fluid

Fluid repellence in one arbitrary phase for repelling the other two phases in a generalized liquid–liquid–air system was achieved on a hydrogen peroxide-treated surface.

scholarly journals Moving mechanisms of the three-phase contact line in a water–decane–silica system

RSC Advances ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 3092-3101 ◽  
Author(s):  
Wenxiu Zheng ◽  
Chengzhen Sun ◽  
Boyao Wen ◽  
Bofeng Bai
Keyword(s):  
Liquid Phase ◽  
Contact Line ◽  
Phase Contact ◽  
Chain Molecules ◽  
System P ◽  
Three Phase

Wettability-related moving mechanisms of the three-phase contact line with one liquid phase composed of chain molecules are revealed.

Neural Model of Coding Stimulus Orientation and Adaptation

2020 ◽  
Vol 32 (4) ◽  
pp. 711-740
Author(s):  
Henrikas Vaitkevičius ◽  
Algimantas Švegžda ◽  
Rytis Stanikūnas ◽  
Remigijus Bliumas ◽  
Alvydas Šoliūnas ◽  
...  
Keyword(s):  
Visual System ◽  
Neural Model ◽  
Line Orientation ◽  
Neural Mechanisms ◽  
Stimulus Orientation ◽  
Tilt Illusion ◽  
Proposed Model ◽  
After Effect ◽  
Orientation Perception ◽  
Normalization Effect

The coding of line orientation in the visual system has been investigated extensively. During the prolonged viewing of a stimulus, the perceived orientation continuously changes (normalization effect). Also, the orientation of the adapting stimulus and the background stimuli influence the perceived orientation of the subsequently displayed stimulus: tilt after-effect (TAE) or tilt illusion (TI). The neural mechanisms of these effects are not fully understood. The proposed model includes many local analyzers, each consisting of two sets of neurons. The first set has two independent cardinal detectors (CDs), whose responses depend on stimulus orientation. The second set has many orientation detectors (OD) tuned to different orientations of the stimulus. The ODs sum up the responses of the two CDs with respective weightings and output a preferred orientation depending on the ratio of CD responses. It is suggested that during prolonged viewing, the responses of the CDs decrease: the greater the excitation of the detector, the more rapid the decrease in its response. Thereby, the ratio of CD responses changes during the adaptation, causing the normalization effect and the TAE. The CDs of the different local analyzers laterally inhibit each other and cause the TI. We show that the properties of this model are consistent with both psychophysical and neurophysiological findings related to the properties of orientation perception, and we investigate how these mechanisms can affect the orientation's sensitivity.

scholarly journals The Effects of Blue Light–Filtering Intraocular Lenses on the Protection and Function of the Visual System

2019 ◽  
Vol Volume 13 ◽  
pp. 2427-2438 ◽  
Author(s):  
Billy R Hammond ◽  
Vidhyapriya Sreenivasan ◽  
Rajaraman Suryakumar
Keyword(s):  
Visual System ◽  
Blue Light ◽  
Intraocular Lenses ◽  
System P ◽  
And Function

8. The physiology and anatomy of the visual system

2017 ◽  
pp. 123-143
Author(s):  
Brian Rogers
Keyword(s):  
Information Processing ◽  
Visual Cortex ◽  
Visual System ◽  
Lateral Inhibition ◽  
Visual Information ◽  
Receptive Fields ◽  
Neural Pathways ◽  
Human Retina ◽  
Feature Detectors ◽  
System P

‘The physiology and anatomy of the visual system’ describes what we have learned from neurophysiology and anatomy over the past eighty years and what this tells us about the meaning of the circuits involved in visual information processing. It explains how psychologists and physiologists use the terms ‘mechanism’ and ‘process’. For physiologists, a mechanism is linked to the actions of individual neurons, neural pathways, and the ways in which the neurons are connected up. For psychologists, the term is typically used to describe the processes the neural circuits may carry out. The human retina is described with explanations of lateral inhibition, receptive fields, and feature detectors as well as the visual cortex and different visual pathways.

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