Two-Dimensional Tilt Illusions Induced by Orthogonal Plaid Patterns: Effects of Plaid Motion, Orientation, Spatial Separation, and Spatial Frequency

Perception ◽  
1989 ◽  
Vol 18 (1) ◽  
pp. 25-38 ◽  
Author(s):  
Peter Wenderoth ◽  
Syren Johnstone ◽  
Rick Van der Zwan
Keyword(s):  
Spatial Frequency ◽  
Real Line ◽  
Repeated Measures ◽  
Spatial Separation ◽  
Frequency Condition ◽  
Angular Function ◽  
Frame Effect ◽  
Tilt Illusion ◽  
Plaid Motion ◽  
Axes Of Symmetry

Tilt illusions occur when a drifting vertical test grating is surrounded by a drifting plaid pattern composed of orthogonal moving gratings. The angular function of this illusion was measured as the plaid orientation (and therefore its drift direction) varied over a 180° range, This was done when the test and inducing stimuli abutted and had the same spatial frequency, and when the test and inducing stimuli either differed in frequency by an octave, or were spatially separated by a 2 deg blank annulus, or both differed in frequency and were also separated by the annulus (experiments 1–4). The obtained angular function was virtually identical to that obtained previously with the rod and frame effect and other cases involving orthogonal inducing components, with evidence for illusions induced both by real-line components and by virtual axes of symmetry. Although the magnitude of the illusion was very similar in all four experiments, there was evidence to suggest that largest real-line effects occurred in the abutting same-frequency condition, with a pattern of results similar to that obtained previously with the simple one-dimensional tilt illusion. On the other hand, virtual-axis effects were more prominent with gaps between test and inducing stimuli. A fifth, repeated-measures, experiment confirmed this pattern of results. It is suggested that this pattern-induced tilt effect reflects both striate and extrastriate mechanisms and that the apparent influence of spatially distal virtual axes of symmetry upon perceived orientation implies the existence of AND-gate mechanisms, or conjunction detectors, in the orientation domain.

Component Analysis of Orientation Illusions

Perception ◽  
1977 ◽  
Vol 6 (1) ◽  
pp. 57-75 ◽  
Author(s):  
Peter Wenderoth ◽  
Helen Beh
Keyword(s):  
Spatial Frequency ◽  
Indirect Effects ◽  
Component Analysis ◽  
Angular Function ◽  
Local Component ◽  
Tilt Illusion ◽  
Global Orientation ◽  
Positive Direct ◽  
Rod And Frame

Orientation illusions occur when the inducing figure is a line or grating (the tilt illusion) or a square outline frame (the rod-and-frame illusion). In the range of inducing figure tilts between vertical and horizontal, the tilt illusion describes one cycle of positive (direct) and negative (indirect) effects but the rod-and-frame illusion describes two such cycles. In two experiments, angular functions of illusions were measured with the six possible inducing figures which result when two of the four sides of a square inducing frame are deleted. As expected, the parallel-sided frame amputations induced angular functions similar to the tilt illusion and these functions differed from those induced by the orthogonal-sided amputations. In agreement with previous findings on the nonadditivity of tilt illusions, the sum of angular functions induced by frame amputations, which together form a complete frame, were not always equivalent to the angular function induced by a complete frame, and there were asymmetries in the data for which neither of two simple hypotheses could adequately account. The discussion focuses upon properties of inducing figures which psychophysical hypotheses might need to consider in order to account for the shapes of angular functions of orientation illusions and, in particular, a distinction is drawn between the global orientation of the inducing figure and the orientations of its (local) component features. It is suggested that it might be fruitful if the tilt illusion and the rod-and-frame illusion were conceived of as illusions resulting from inducing figures composed of all or part of n gratings of spatial frequency fn intersecting at angles of 180°/ n.

The Distinction between the Rod-and-Frame Illusion and the Rod-and-Frame Test

Perception ◽  
1974 ◽  
Vol 3 (2) ◽  
pp. 205-212 ◽  
Author(s):  
P M Wenderoth
Keyword(s):  
Angular Function ◽  
Frame Effect ◽  
Tilt Illusion ◽  
Single Frame ◽  
Frame Tilt ◽  
Attraction Effects ◽  
Gravitational Vertical ◽  
Rod And Frame Test ◽  
Rod And Frame

Errors in vertical settings of a test rod occur when the rod is enclosed in a laterally-tilted square-outline frame. The majority of previous experiments which have investigated this rod-and-frame effect have used a single frame tilt, usually 28°, and have tabulated errors as average unsigned deviations from gravitational vertical. Evidence is presented that, when the illusion is measured by taking algebraic differences between constant (signed) errors made with and without the frame being present, illusions occur in the direction of frame tilt for frame tilts up to about 25° from vertical (repulsion effects) but that directionally opposite illusions (attraction effects) occur for frame tilts between 25° and 45°. At the frame tilts used most frequently in previous studies (25° to 30°) little or no illusion occurs. A distinction is drawn between the rod-and-frame illusion (RFI), which has an angular function similar to the simple tilt illusion and aftereffect, and the rod-and-frame test (RFT), which uses unsigned deviations from vertical as its measure of error and which probably bears little or no relationship to the RFI.

Comparison at a Distance

Perception ◽  
10.1068/p3393 ◽  
2003 ◽  
Vol 32 (4) ◽  
pp. 395-414 ◽  
Author(s):  
Marina V Danilova ◽  
John D Mollon
Keyword(s):  
Visual Field ◽  
Spatial Frequency ◽  
Visual System ◽  
Spatial Separation ◽  
Orientation Discrimination ◽  
Human Observer ◽  
Systematic Effect ◽  
Trained Subjects ◽  
Stimulus Attribute ◽  
The Subject

The visual system is known to contain hard-wired mechanisms that compare the values of a given stimulus attribute at adjacent positions in the visual field; but how are comparisons performed when the stimuli are not adjacent? We ask empirically how well a human observer can compare two stimuli that are separated in the visual field. For the stimulus attributes of spatial frequency, contrast, and orientation, we have measured discrimination thresholds as a function of the spatial separation of the discriminanda. The three attributes were studied in separate experiments, but in all cases the target stimuli were briefly presented Gabor patches. The Gabor patches lay on an imaginary circle, which was centred on the fixation point and had a radius of 5 deg of visual angle. Our psychophysical procedures were designed to ensure that the subject actively compared the two stimuli on each presentation, rather than referring just one stimulus to a stored template or criterion. For the cases of spatial frequency and contrast, there was no systematic effect of spatial separation up to 10 deg. We conclude that the subject's judgment does not depend on discontinuity detectors in the early visual system but on more central codes that represent the two stimuli individually. In the case of orientation discrimination, two naïve subjects performed as in the cases of spatial frequency and contrast; but two highly trained subjects showed a systematic increase of threshold with spatial separation, suggesting that they were exploiting a distal mechanism designed to detect the parallelism or non-parallelism of contours.

Exposure-Time and Spatial-Frequency Effects in the Tilt Illusion

Perception ◽  
1979 ◽  
Vol 8 (5) ◽  
pp. 557-564 ◽  
Author(s):  
Brian I O'Toole
Keyword(s):  
Spatial Frequency ◽  
Indirect Effects ◽  
Time Course ◽  
Test Line ◽  
Acute Angle ◽  
Direct Effects ◽  
Time Constants ◽  
Frequency Effects ◽  
Tilt Illusion ◽  
Vertical Test

The exposure durations of a vertical test line and a tilted inducing grating were varied and the tilt illusion thus generated was found to change as a function of this variation. Significant direct effects (acute-angle expansion) and indirect effects (acute-angle contraction) were found to occur at times consistent with Andrews's estimate of the time course of inhibition in the visual system when the inducing grating had a spatial frequency of 10 cycles deg−1. However, a 2 · 71 cycles deg−1 grating gave significant effects at exposure durations of 10 as well as 1000 ms, while in a further experiment a 10 · 91 cycles deg−1 grating gave significant effects at 1000 ms only. These results seem to suggest that orientation interactions thought to be due to inhibition (direct effect) and disinhibition (indirect effect) may occur within both sustained and transient channels with concomitant differences in time constants.

scholarly journals Метод формирования единственного сфокусированного порядка дифракции при помощи бинарных амплитудных дифракционных элементов без пространственной несущей

2021 ◽  
Vol 129 (4) ◽  
pp. 436
Author(s):  
В.В. Краснов ◽  
Р.С. Стариков ◽  
Е.Ю. Злоказов
Keyword(s):  
Spatial Frequency ◽  
Wave Front ◽  
Diffraction Efficiency ◽  
Incident Wave ◽  
Diffraction Order ◽  
Spatial Separation ◽  
Iteration Algorithm ◽  
Self Focusing ◽  
Random Trajectory ◽  
Two Stages

The method of synthesis of self-focusing amplitude DOE without the carrier spatial frequency working in divergent beams and forming single focused diffraction order which can occupy whole DOE reconstruction field because there is no necessity for spatial separation of diffraction orders, which is the case with holograms, is presented. Synthesis was carried out in two stages. The first one was carried out by the iteration algorithm similar to Gerchberg-Saxton algorithm, with those differences that synthesizable DOE is an amplitude one and incident wave front is divergent. Then the method of direct search with random trajectory was applied. As a result for binary amplitude DOE synthesis error of 6% and diffraction efficiency of 6% was achieved. Results of experimental DOE implementation using DMD are presented.

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.

Spatial Frequency Selectivity of a Visual Tilt Illusion

Nature ◽  
1973 ◽  
Vol 245 (5419) ◽  
pp. 43-45 ◽  
Author(s):  
MARK A. GEORGESON
Keyword(s):  
Spatial Frequency ◽  
Frequency Selectivity ◽  
Tilt Illusion

Spatial frequency and duration effects on the tilt illusion and orientation acuity

1988 ◽  
Vol 28 (9) ◽  
pp. 1051-1059 ◽  
Author(s):  
J.E. Calvert ◽  
J.P. Harris
Keyword(s):  
Spatial Frequency ◽  
Tilt Illusion

scholarly journals Speech Recognition and Temporal Processing in Middle-Aged Women

2009 ◽  
Vol 20 (04) ◽  
pp. 264-271 ◽  
Author(s):  
Karen S. Helfer ◽  
Megan Vargo
Keyword(s):  
Steady State ◽  
Temporal Processing ◽  
Repeated Measures ◽  
Pure Tone ◽  
Spatial Separation ◽  
Strong Relationship ◽  
Speech Understanding ◽  
Middle Aged ◽  
Aged Subjects ◽  
Competing Speech

Purpose: This study was designed to examine speech understanding ability and temporal processing in middle-aged women with normal or near-normal pure-tone thresholds. Research Design: Speech understanding, temporal processing ability, and self-assessed hearing were measured in groups of younger and middle-aged females. Study Sample: Participants were younger and middle-aged females (n = 12 per group) with normal hearing through 4000 Hz bilaterally. Subjects were drawn from nonclinical populations. Data Collection and Analysis: Speech understanding was measured in the presence of steady-state noise and competing speech, with and without perceived spatial separation of the target speech and masker. The Gaps-In-Noise (GIN) test (Musiek et al, 2005) was used to assess temporal resolution ability. In addition, subjects completed a questionnaire with several items from the Speech, Spatial, and Qualities of Hearing Scale (Gatehouse and Noble, 2004) to gauge their subjective ability to understand speech in complex listening situations. Data were analyzed via repeated-measures ANOVA and Pearson r correlations. Results: Results showed that the performance of the middle-aged subjects was significantly poorer than that of the younger participants in the presence of a spatially coincident speech masker. Although performance in this listening condition was unrelated to pure-tone thresholds, it was strongly correlated with scores on the GIN test. Speech understanding performance in the presence of a steady-state masker was related to high-frequency pure-tone thresholds. Conclusions: These results suggest that some middle-aged women with little or no pure-tone hearing loss experience listening difficulty in complex environments. Results also suggest a strong relationship between temporal processing and speech understanding in certain competing speech situations.

Sign in / Sign up

Export Citation Format

Share Document