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.

Contrast adaptation in retinal and cortical evoked potentials: No adaptation to low spatial frequencies

2002 ◽  
Vol 19 (5) ◽  
pp. 645-650 ◽  
Author(s):  
THOMAS STEPHAN HEINRICH ◽  
MICHAEL BACH
Keyword(s):  
Spatial Frequency ◽  
Visual Evoked Potential ◽  
Evoked Potential ◽  
Opposite Effect ◽  
Pattern Electroretinogram ◽  
Low Contrast ◽  
Contrast Adaptation ◽  
Spatial Frequencies ◽  
Sinusoidal Gratings ◽  
Cross Adaptation

Contrast adaptation occurs in both the retina and the cortex. Defining its spatial dependence is crucial for understanding its potential roles. We thus asked to what degree contrast adaptation depends on spatial frequency, including cross-adaptation. Measuring the pattern electroretinogram (PERG) and the visual evoked potential (VEP) allowed separating retinal and cortical contributions. In ten subjects we recorded simultaneous PERGs and VEPs. Test stimuli were sinusoidal gratings of 98% contrast with spatial frequencies of 0.5 or 5.0 cpd, phase reversing at 17 reversals/s. Adaptation was controlled by prolonged presentation of these test stimuli or homogenous gray fields of the same luminance. When adaptation and test frequency were identical, we observed significant contrast adaptation only at 5 cpd: an amplitude reduction in the PERG (−22%) and VEP (−58%), and an effective reduction of latency in the PERG (−0.95 ms). When adapting at 5 cpd and testing at 0.5 cpd, the opposite effect was observed: enhancement of VEP amplitude by +26% and increase in effective PERG latency by +1.35 ms. When adapting at 0.5 cpd and testing at 5 cpd, there was no significant amplitude change in PERG and VEP, but a small effective PERG latency increase of +0.65 ms. The 0.5-cpd channel was not adapted by spatial frequencies of 0.5 cpd. The adaptability of the 5-cpd channel may mediate improved detail recognition after prolonged blur. The existence of both adaptable and nonadaptable mechanisms in the retina allows for the possibility that by comparing the adaptational state of spatial-frequency channels the retina can discern between overall low contrast and defocus in emmetropization control.

Right-Hemisphere Superiority in the Discrimination of Spatial Phase

Perception ◽  
1984 ◽  
Vol 13 (6) ◽  
pp. 695-708 ◽  
Author(s):  
Adriana Fiorentini ◽  
Nicoletta Berardi
Keyword(s):  
Spatial Frequency ◽  
Right Hemisphere ◽  
Frequency Discrimination ◽  
High Contrast ◽  
Spatial Phase ◽  
Phase Discrimination ◽  
Visual Hemifield ◽  
Spatial Frequencies ◽  
Sinusoidal Gratings ◽  
The Right

Visual field differences have been investigated in various detection and discrimination tasks for simple sinusoidal gratings or for complex gratings composed of two sinusoids of spatial frequencies f and 3 f. Sinusoidal gratings were employed to evaluate contrast sensitivity, subthreshold summation effects, aftereffects of adaptation to a high-contrast grating, and spatial-frequency discrimination. The tasks with complex gratings were detection of the 3 f component in the presence of a high-contrast f component and spatial-phase discrimination. The stimuli were presented either in the left or in the right visual hemifield. The results indicate a lack of lateralization for detection and spatial-frequency discrimination of sinusoidal gratings, and for the bandwidth of subthreshold summation effects and adaptation aftereffects, whereas the detection of the 3 f component in the presence of a high-contrast f component, as well as spatial-phase discrimination of f + 3 f gratings, show a left-field advantage. This suggests a right-hemisphere superiority in the processing of spatial phase.

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.

Orientation Specificity and Spatial Selectivity in Human Vision

Perception ◽  
1973 ◽  
Vol 2 (1) ◽  
pp. 53-60 ◽  
Author(s):  
J A Movshon ◽  
C Blakemore
Keyword(s):  
Spatial Frequency ◽  
Human Visual System ◽  
Human Vision ◽  
Orientation Tuning ◽  
High Contrast ◽  
Vertical Grating ◽  
Spatial Frequencies ◽  
High Contrast Grating ◽  
Orientation Specificity ◽  
Adaptation Method

An adaptation method is used to determine the orientation specificity of channels sensitive to different spatial frequencies in the human visual system. Comparison between different frequencies is made possible by a data transformation in which orientational effects are expressed in terms of equivalent contrast (the contrast of a vertical grating producing the same adaptational effect as a high-contrast grating of a given orientation). It is shown that, despite great variances in the range of orientations affected by adaptation at different spatial frequencies (±10° to ±50°), the half-width at half-amplitude of the orientation channels does not vary systematically as a function of spatial frequency over the range tested (2·5 to 20 cycles deg−1). Two subjects were used and they showed significantly different orientation tuning across the range of spatial frequencies. The results are discussed with reference to previous determinations of orientation specificity, and to related psychophysical and neurophysiological phenomena.

Monkeys Show an Oblique Effect

Perception ◽  
1979 ◽  
Vol 8 (3) ◽  
pp. 247-253 ◽  
Author(s):  
Joseph A Bauer ◽  
Donald A Owens ◽  
Joseph Thomas ◽  
Richard Held
Keyword(s):  
Animal Model ◽  
Spatial Frequency ◽  
Oblique Effect ◽  
High Contrast ◽  
Square Wave ◽  
Spatial Frequencies

Monkeys aligned a cursor bar with high-contrast square-wave gratings presented in a variety of orientations. Alignment time increased with increasing spatial frequency from 6 to 24 cycles deg−1 regardless of the orientation of the grating. At higher spatial frequencies, alignment tasks took longer for obliquely oriented gratings than for horizontal and vertical ones. Reducing grating contrast by blurring the image of the 24 cycle deg−1 grating also produced longer alignment times for the obliques. These data indicate that monkeys have an oblique effect similar to that found in humans, implying that the monkey is a useful animal model for investigating the development of meridional anisotropies.

Flicker Masking and Developmental Dyslexia

Perception ◽  
1986 ◽  
Vol 15 (4) ◽  
pp. 473-482 ◽  
Author(s):  
Andrew T Smith ◽  
Frances Early ◽  
Sarah C Grogan
Keyword(s):  
Spatial Frequency ◽  
Visual System ◽  
Developmental Dyslexia ◽  
Cell Function ◽  
Cell Activity ◽  
Reaction Times ◽  
Visual Persistence ◽  
Reading Impairment ◽  
Spatial Frequencies

Recent studies have provided evidence that dyslexic children tend to show longer visual persistence than control children when presented with low-spatial-frequency grating stimuli. The possibility that this phenomenon might reflect an impairment of inhibitory Y-cell activity in the visual system of dyslexics has been investigated. A flicker masking technique was used to mask Y-cell activity selectively in a group of dyslexic boys and a group of age-matched controls. There were no overall differences in reaction times to the offsets of grating patterns of various spatial frequencies between the groups, and no differences between subgroups defined by age, degree of reading impairment, or any other criterion. The results show no evidence of abnormal Y-cell function in developmental dyslexia.

Suprathreshold Stereo-Depth Matches as a Function of Contrast and Spatial Frequency

Perception ◽  
1986 ◽  
Vol 15 (3) ◽  
pp. 249-258 ◽  
Author(s):  
Clifton M Schor ◽  
Peter A Howarth
Keyword(s):  
Spatial Frequency ◽  
Depth Perception ◽  
Low Frequency ◽  
Stereoscopic Depth ◽  
Apparent Depth ◽  
Black Line ◽  
Low Contrast ◽  
Spatial Frequencies ◽  
Vertical Bars ◽  
Thin Black Line

Thresholds for stereoscopic-depth perception increase with decreasing spatial frequency below 2.5 cycles deg−1. Despite this variation of stereo threshold, suprathreshold stereoscopic-depth perception is independent of spatial frequency down to 0.5 cycle deg-1. Below this frequency the perceived depth of crossed disparities is less than that stimulated by higher spatial frequencies which subtend the same disparities. We have investigated the effects of contrast fading upon this breakdown of stereo-depth invariance at low spatial frequencies. Suprathreshold stereopsis was investigated with spatially filtered vertical bars (difference of Gaussian luminance distribution, or DOG functions) tuned narrowly over a broad range of spatial frequencies (0.15–9.6 cycles deg−1). Disparity subtended by variable width DOGs whose physical contrast ranged from 10–100% was adjusted to match the perceived depth of a standard suprathreshold disparity (5 min visual angle) subtended by a thin black line. Greater amounts of crossed disparity were required to match broad than narrow DOGs to the apparent depth of the standard black line. The matched disparity was greater at low than at high contrast levels. When perceived contrast of all the DOGs was matched to standard contrasts ranging from 5–72%, disparity for depth matches became similar for narrow and broad DOGs. 200 ms pulsed presentations of DOGs with equal perceived contrast further reduced the disparity of low-contrast broad DOGs needed to match the standard depth. A perceived-depth bias in the uncrossed direction at low spatial frequencies was noted in these experiments. This was most pronounced for low-contrast low-spatial-frequency targets, which actually needed crossed disparities to make a depth match to an uncrossed standard. This bias was investigated further by making depth matches to a zero-disparity standard (ie the apparent fronto-parallel plane). Broad DOGs, which are composed of low spatial frequencies, were perceived behind the fixation plane when they actually subtended zero disparity. The magnitude of this low-frequency depth bias increased as contrast was reduced. The distal depth bias was also perceived monocularly, however, it was always greater when viewed binocularly. This investigation indicates that contrast fading of low-spatial-frequency stimuli changes their perceived depth and enhances a depth bias in the uncrossed direction. The depth bias has both a monocular and a binocular component.

Direction-sensitive X and Y cells within the A laminae of the cat's LGNd

1994 ◽  
Vol 11 (5) ◽  
pp. 927-938 ◽  
Author(s):  
Kirk G. Thompson ◽  
Yifeng Zhou ◽  
Audie G. Leventhal
Keyword(s):  
Visual Cortex ◽  
Spatial Frequency ◽  
Preferred Orientation ◽  
General Direction ◽  
Preferred Direction ◽  
X And Y Cells ◽  
Spatial Frequencies ◽  
Sinusoidal Gratings ◽  
Direction Sensitivity ◽  
Y Cells

AbstractDrifting sinusoidal gratings, moving bars, and moving spots were employed to study the direction sensitivity of 425 neurons in the A laminae of the cat's LGNd. Thirty-two percent of X- and Y-type LGNd relay cells exhibit significant direction sensitivity when tested with drifting sinusoidal gratings. X and Y cells exhibit the same degree of direction sensitivity. Moving spots and bars elicit direction specific responses from LGNd cells that are consistent with those elicited when drifting sinusoidal gratings are employed. For cells that are both orientation and direction sensitive, the preferred direction tends to be orthogonal to the preferred orientation. In general, direction sensitivity is strongest at relatively low spatial frequencies, well below the spatial-frequency cutoff for the cell. The presence of significant numbers of direction-sensitive LGNd cells raises the possibility that subcortical direction specificity is important for the generation of this property in the visual cortex.

The physics of visual perception

1980 ◽  
Vol 290 (1038) ◽  
pp. 5-9 ◽  
Keyword(s):  
Visual Perception ◽  
Spatial Frequency ◽  
Visual System ◽  
Contrast Threshold ◽  
High Contrast ◽  
Spatial Frequencies ◽  
Band Pass ◽  
High Contrast Grating ◽  
Orientational Tuning

By measuring the contrast threshold for gratings of different waveform and spatial frequency, Campbell & Robson suggested in 1968 that there may be ‘channels’ tuned to different spatial frequencies. By using the technique of adapting to a high contrast grating, it was possible to measure the band-pass characteristics of these channels. Similar techniques were used to establish the orientational tuning of the channels. Reasons are put forward why it is advantageous to organize the visual system in this manner.

Orientation and Direction Tuning of Goldfish Ganglion Cells

1989 ◽  
Vol 2 (1) ◽  
pp. 3-13 ◽  
Author(s):  
Joseph Bilotta ◽  
Israel Abramov
Keyword(s):  
Receptive Field ◽  
Spatial Frequency ◽  
Ganglion Cell ◽  
Ganglion Cells ◽  
Receptive Fields ◽  
Orientation Tuning ◽  
Retinal Ganglion ◽  
Spatial Frequencies ◽  
Sinusoidal Gratings ◽  
Direction Tuning

AbstractOrientation and direction tuning were examined in goldfish ganglion cells by drifting sinusoidal gratings across the receptive field of the cell. Each ganglion cell was first classified as X-, Y- or W-like based on its responses to a contrast-reversal grating positioned at various spatial phases of the cell's receptive field. Sinusoidal gratings were drifted at different orientations and directions across the receptive field of the cell; spatial frequency and contrast of the grating were also varied. It was found that some X-like cells responded similarly to all orientations and directions, indicating that these cells had circular and symmetrical fields. Other X-like cells showed a preference for certain orientations at high spatial frequencies suggesting that these cells possess an elliptical center mechanism (since only the center mechanism is sensitive to high spatial frequencies). In virtually all cases, X-like cells were not directionally tuned. All but one Y-like cell displayed orientation tuning but, as with X-like cells, orientation tuning appeared only at high spatial frequencies. A substantial portion of these Y-like cells also showed a direction preference. This preference was dependent on spatial frequency but in a manner different from orientation tuning, suggesting that these two phenomena result from different mechanisms. All W-like cells possessed orientation and direction tuning, both of which depended on the spatial frequency of the stimulus. These results support past work which suggests that the center and surround components of retinal ganglion cell receptive fields are not necessarily circular or concentric, and that they may actually consist of smaller subareas.

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