Visual Stimuli for Strabismic Suppression

Perception ◽  
1977 ◽  
Vol 6 (5) ◽  
pp. 583-593 ◽  
Author(s):  
Clifton M Schor
Keyword(s):  
Spatial Frequency ◽  
Binocular Vision ◽  
Binocular Rivalry ◽  
Visual Stimuli ◽  
Normal Group ◽  
Sensory Fusion ◽  
Sinusoidal Gratings

The effects of orientation and spatial frequency of grating stimuli upon suppression were examined with a binocular rivalry paradigm in a group of ten strabismic patients and in a control normal group. Duration, frequency, and period of rivalry were examined as functions of differences in orientation and spatial frequency of dichoptic achromatic sinusoidal gratings. Records were made of responses by the sighting and by the nonsighting eye as well as responses during periods of combined binocular vision. Strabismic subjects reported normal binocular rivalry when presented with gratings of dissimilar orientation. Suppression of the deviating eye in strabismic subjects occurred with stimuli of similar orientation and was unaffected by spatial-frequency differences between dichoptic stimuli. Suppression was most intense under conditions that normally stimulate stereopsis and sensory fusion.

A Dissociation between Reaction Time to Sinusoidal Gratings and Temporal-Order Judgment

Perception ◽  
1994 ◽  
Vol 23 (3) ◽  
pp. 335-347 ◽  
Author(s):  
Thomas Tappe ◽  
Michael Niepel ◽  
Odmar Neumann
Keyword(s):  
Reaction Time ◽  
Spatial Frequency ◽  
Comparison Stimulus ◽  
Motor System ◽  
Temporal Order ◽  
Temporal Order Judgment ◽  
Visual Stimuli ◽  
Visual Latency ◽  
Sinusoidal Gratings ◽  
Sharp Edges

The effect of the spatial frequency (SF) of visual gratings on reaction time (RT) and temporal-order judgment (TOJ) was examined in three experiments. In experiment 1 the visual stimuli were vertical sinusoidal gratings with SFs between 2 and 8 cycles deg−1 and the comparison stimulus in the TOJ task was a 2300 Hz tone. Whereas SF had a highly significant effect on RT, it left TOJ completely unaffected. To test whether this dissociation was due to the sharp (high SF) horizontal edges of the gratings, a second experiment was carried out with circular stimuli with no sharp edges. These stimuli did produce an effect of SF on TOJ, but it was significantly smaller than was the effect on RT. In experiment 3 we confirmed that this difference was not due to differences in grating orientation between the first two experiments. These findings (a) solve discrepancies between findings reported in the literature and (b) strongly suggest that RT and TOJ cannot be regarded as converging operations for determining ‘visual latency’. This dissociation can best be accounted for by assuming that the output of early stimulus analysis can feed directly into the motor system (direct parameter specification), whereas the conscious representation that is used for TOJ is based on later integrative processes.

Adaptation in single units in visual cortex: The tuning of aftereffects in the spatial domain

1989 ◽  
Vol 2 (6) ◽  
pp. 593-607 ◽  
Author(s):  
A. B. Saul ◽  
M. S. Cynader
Keyword(s):  
Spatial Frequency ◽  
Cortical Neurons ◽  
Frequency Tuning ◽  
Cortical Cell ◽  
Selective Adaptation ◽  
Single Units ◽  
Spatial Frequency Tuning ◽  
Sinusoidal Gratings ◽  
A Cell ◽  
Drift Direction

AbstractCat striate cortical neurons were investigated using a new method of studying adaptation aftereffects. Stimuli were sinusoidal gratings of variable contrast, spatial frequency, and drift direction and rate. A series of alternating adapting and test trials was presented while recording from single units. Control trials were completely integrated with the adapted trials in these experiments.Every cortical cell tested showed selective adaptation aftereffects. Adapting at suprathreshold contrasts invariably reduced contrast sensitivity. Significant aftereffects could be observed even when adapting at low contrasts.The spatial-frequency tuning of aftereffects varied from cell to cell. Adapting at a given spatial frequency generally resulted in a broad response reduction at test frequencies above and below the adapting frequency. Many cells lost responses predominantly at frequencies lower than the adapting frequency.The tuning of aftereffects varied with the adapting frequency. In particular, the strongest aftereffects occurred near the adapting frequency. Adapting at frequencies just above the optimum for a cell often altered the spatial-frequency tuning by shifting the peak toward lower frequencies. The fact that the tuning of aftereffects did not simply match the tuning of the cell, but depended on the adapting stimulus, implies that extrinsic mechanisms are involved in adaptation effects.

Pleasingness vs Interestingness of Visual Stimuli with Controlled Complexity: Their Relationship to Looking Time as a Function of Exposure Time

1975 ◽  
Vol 40 (1) ◽  
pp. 3-7 ◽  
Author(s):  
Gerda Smets
Keyword(s):  
Exposure Time ◽  
Binocular Rivalry ◽  
Stimulus Pair ◽  
Significant Interaction ◽  
Visual Stimuli ◽  
The Other ◽  
Stimulus Complexity

Ss take more time to perceive interesting/displeasing stimuli than uninteresting/pleasing ones. This is consistent with the results of former experiments. However we used a different operationalization of looking time, based on binocular rivalry. Each of six stimulus pairs was presented in a stereoscope. One member of each pair was interesting but displeasing in comparison to the other member. Stimulus complexity was under control. Due to binocular rivalry Ss perceived only one pattern a time. 20 Ss were asked to indicate which pattern they actually saw by pushing two buttons. For each stimulus pair was registered how long each button was pushed during each of six successive minutes. Unlike other operationalizations this one is less dependent on S's determination of what stimulus will be looked at or for how long. It has the advantage that it is bound up more exclusively with relations of similarity and dissimilarity between stimulus elements. It allows manipulation of exposure time in a systematic and continuous way. There is no significant interaction between looking and exposure time.

Temporal-Discontinuity Detection with Contrast-Modulated Gratings

Perception ◽  
1995 ◽  
Vol 24 (11) ◽  
pp. 1257-1264
Author(s):  
Shigeru Ichihara ◽  
Kenji Susami
Keyword(s):  
Spatial Frequency ◽  
Modulation Frequency ◽  
Sinusoidal Grating ◽  
Local Contrast ◽  
Staircase Method ◽  
Low Contrast ◽  
Discontinuity Detection ◽  
Temporal Discontinuity ◽  
Sinusoidal Gratings ◽  
The Subject

Three experiments on temporal-discontinuity detection were carried out. In experiment 1, temporal-discontinuity thresholds were measured for sinusoidal gratings by the use of the double-staircase method. A sinusoidal grating was presented twice successively. The subject judged whether or not an interval was present. The temporal-discontinuity threshold increased as the spatial frequency of the grating increased, but decreased as the contrast of the grating increased. In experiment 2, contrast-modulated gratings were used instead of the sinusoidal grating. The temporal-discontinuity threshold increased as the carrier frequency increased, and the threshold for each contrast-modulated grating was similar to that for the no-modulation (sinusoidal) grating whose contrast was the same as the maximum local contrast of the contrast-modulated grating. In experiment 3, temporal-discontinuity thresholds were measured for low-contrast (3%) sinusoidal gratings. The thresholds were very low, even for such low-contrast gratings. These results suggest that the low-spatial-frequency channels are not involved in detecting the modulation frequency of the contrast-modulated grating. Rather, the local contrast seems to be the determinant of the detection of the contrast-modulated grating itself.

The Effect of Spatial Frequency and Contrast on Visual Persistence

Perception ◽  
1979 ◽  
Vol 8 (5) ◽  
pp. 529-539 ◽  
Author(s):  
Alison Bowling ◽  
William Lovegrove ◽  
Barry Mapperson
Keyword(s):  
Spatial Frequency ◽  
Visual Persistence ◽  
Published Data ◽  
High Contrast ◽  
Low Contrast ◽  
Spatial Frequencies ◽  
Sinusoidal Gratings

The visual persistence of sinusoidal gratings of varying spatial frequency and contrast was measured. It was found that the persistence of low-contrast gratings was longer than that of high-contrast stimuli for all spatial frequencies investigated. At higher contrast levels of 1 and 4 cycles deg−1 gratings, a tendency for persistence to be independent of contrast was observed. For 12 cycles deg−1 gratings, however, persistence continued to decrease with increasing contrast. These results are compared with recently published data on other temporal responses, and are discussed in terms of the different properties of sustained and transient channels.

Texture Preference and Global Frequency Magnitudes

2003 ◽  
Vol 30 (2) ◽  
pp. 297-318 ◽  
Author(s):  
Gretchen Schira
Keyword(s):  
Spatial Frequency ◽  
Physical Properties ◽  
Visual Stimuli ◽  
Gabor Filters ◽  
Visual Texture ◽  
Aesthetic Preference

A relationship between human preferences for physical properties of visual texture is established in this paper. The author asks whether there is a measurable correlation between aesthetic ratings for textural images and their physical properties. A bank of Gabor filters covering a range of frequencies and orientations are used to extract properties. Three studies are conducted and the correlations between aesthetic ratings and the properties were significant and large. The correlations proved robust when image identifiability was incorporated in the first and third studies and removed from the second study. In this, it is suggested that memory and association are not exclusively driving (aesthetic) preference; that it is also tuned to properties of spatial frequency and orientation of certain visual stimuli.

The Sensitivity of Binocular Rivalry Suppression to Changes in Orientation Assessed by Reaction-Time and Forced-Choice Techniques

Perception ◽  
1981 ◽  
Vol 10 (3) ◽  
pp. 283-293 ◽  
Author(s):  
Robert P O'Shea ◽  
Boris Crassini
Keyword(s):  
Reaction Time ◽  
Spatial Frequency ◽  
Binocular Rivalry ◽  
Luminance Contrast ◽  
Forced Choice ◽  
Field Size ◽  
Correct Performance ◽  
Orientation Change ◽  
Choice Procedure ◽  
Forced Choice Procedure

Binocular rivalry was induced between two orthogonal square-wave gratings of the same spatial frequency, luminance, contrast, and field size, presented dichoptically. One of the gratings could be instantly replaced by a third grating differing only in orientation. In one experiment subjects were required to respond as soon as an orientation change was noticed, and to withold response to catch trials (no orientation change). When orientation changes were made to the visible grating, reaction time was found to be a U-shaped function of the magnitude of orientation change. When orientation changes were made to the grating undergoing binocular-rivalry suppression, an overall increase in reaction time was found with the increase being greater for large orientation changes (an asymmetrical U-shaped function). In another experiment subjects were required to detect the direction of a change in orientation in a two-alternative forced-choice procedure. Thresholds were thus obtained for 75% correct performance. It was found that thresholds for orientation changes made to the visible and invisible fields were identical from 20° to 70° orientation change. Outside this range thresholds were higher when orientation changes were made to the field suppressed by binocular rivalry. It is argued that the orientation functions obtained in the two experiments may represent incomplete suppression of either form or transient information during binocular rivalry.

Edge Computation in Human Vision: Anisotropy in the Combining of Oriented Filters

Perception ◽  
1995 ◽  
Vol 24 (6) ◽  
pp. 603-622 ◽  
Author(s):  
Tim S Meese ◽  
Tom C A Freeman
Keyword(s):  
Spatial Structure ◽  
Spatial Frequency ◽  
Human Vision ◽  
Contrast Effects ◽  
Compound Structure ◽  
Component Structure ◽  
Zero Crossings ◽  
Coding Scheme ◽  
Two Component ◽  
Sinusoidal Gratings

Above threshold, two superimposed sinusoidal gratings of the same spatial frequency (eg 1 cycle deg−1) and equal contrasts, and with orientations balanced around vertical, usually look like a compound structure containing vertical and horizontal edges. However, at large plaid angles (ie large differences between component orientations) and low plaid contrasts there is a tendency for the stimulus to appear as two overlapping gratings (component structure) with obliquely oriented edges. These dependencies of perceived spatial structure in plaids are incompatible with an edge-coding scheme that uses only circular filters to compute zero-crossings, but instead support the idea that different oriented filters can (compound percept) or cannot (component percept) be combined before edges are represented. Here, further evidence is presented in support of this hypothesis. Two-component plaid stimuli had plaid angles of 45° or 90°, and a range of plaid orientations (ie a range of orientations around which the plaid components were balanced). Observers indicated whether each stimulus was perceived as a compound or component structure for a range of plaid contrasts. In addition to angle and contrast effects, perceived spatial structure was also found to depend on plaid orientation: compound structures were perceived more often when the plaid components were balanced around the cardinal axes of the retina. It is suggested that the principles governing the combination of oriented-filter outputs might be learnt during the development of the visual system by using a Hebb-type rule: coactivated filters are more likely to combine their outputs when activated on future occasions. Given the prominence of vertical and horizontal orientations in a carpentered environment, this simple rule promotes a network that combines filters balanced around cardinal axes more readily than oblique axes, in agreement with the results.

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