Dynamics of Adaptation to Contrast

Perception ◽  
1982 ◽  
Vol 11 (5) ◽  
pp. 505-528 ◽  
Author(s):  
David Rose ◽  
Ivan Lowe
Keyword(s):  
Spatial Frequency ◽  
Visual System ◽  
Power Function ◽  
Single Phase ◽  
Detection Threshold ◽  
High Spatial Frequency ◽  
Sinusoidal Grating ◽  
Dual Phase ◽  
High Contrast ◽  
Inhibitory Interactions

An investigation has been made into the temporal parameters with which the detection threshold for a sinusoidal grating changes during and after adaptation to the same grating at high contrast. Stationary high-spatial-frequency gratings and a phase-reversing low-spatial-frequency grating have been studied separately. It was found that the threshold continues to rise during adaptation for at least 6 min without sign of levelling off, and that full recovery from 6 min of adaptation can take more than 45 min. Intermittent adaptation and continuous adaptation for the same period produce similar effects. Single-phase and dual-phase exponential fits to the data are rejected, and it is concluded that the level of adaptation of the visual system to spatial contrast changes as a power function of time. However, recovery is not always monotonic, especially after adaptation to phase-reversing gratings. This may be due to inhibitory interactions between channels (in particular, those for pattern and movement information).

Temporal summation of moving images by the human visual system

1981 ◽  
Vol 211 (1184) ◽  
pp. 321-339 ◽  
Keyword(s):  
Spatial Frequency ◽  
Visual System ◽  
Human Visual System ◽  
Temporal Summation ◽  
Temporal Integration ◽  
High Spatial Frequency ◽  
Slow Motion ◽  
Sinusoidal Grating ◽  
Moving Images ◽  
Sinusoidal Gratings

Measurements of threshold visibility were made as a function of duration of stimulus exposure for small moving dot targets, drifting sinusoidal gratings and moving patches of sinusoidal gratings, to investigate how the human visual nervous system summates over time signals arising from stimuli in motion. At image speeds of less that 16 deg/s, temporal summation is as strong and as extended for moving as for stationary dots (total summation over to about 100 ms). This summation is about twice that which would be expected from separate consideration of the regions of spatial and temporal integration. Measurements with sinusoidal gratings reveal that the nature of the summation depends critically on the spatial frequency of the stimulus: gratings of low spatial frequency summate well when in motion (and only when in motion), whereas those of high spatial frequency summate well only when stationary or in very slow motion. An analogue simulation with electronic filters showed that these psychophysical results are directly predictable from the known transfer characteristics of the human visual system (with the additional assumption of probability summation at threshold). Finally, with small patches of sinusoidal grating, it was established that translation per se across the retina has little effect on temporal summation. This suggests that the results obtained with sinusoidal gratings of large extent are also relevant to small moving stimuli, allowing the summation results obtained with dot stimuli to be discussed in terms of the temporal transfer properties of spatially selective visual detectors. On the basis of these results it is proposed that the extended temporal summation observed for dots in motion results from summation of energy of low spatial frequency present in these stimuli.

scholarly journals Is Peripheral Motion Detection Affected by Myopia?

2021 ◽  
Vol 15 ◽  
Author(s):  
Junhan Wei ◽  
Deying Kong ◽  
Xi Yu ◽  
Lili Wei ◽  
Yue Xiong ◽  
...  
Keyword(s):  
Visual Field ◽  
Spatial Frequency ◽  
Motion Detection ◽  
High Speed ◽  
Detection Threshold ◽  
High Spatial Frequency ◽  
Spherical Equivalent ◽  
Detection Thresholds ◽  
Significant Difference ◽  
Motion Speed

PurposeThe current study was to investigate whether myopia affected peripheral motion detection and whether the potential effect interacted with spatial frequency, motion speed, or eccentricity.MethodsSeventeen young adults aged 22–26 years participated in the study. They were six low to medium myopes [spherical equivalent refractions −1.0 to −5.0 D (diopter)], five high myopes (<-5.5 D) and six emmetropes (+0.5 to −0.5 D). All myopes were corrected by self-prepared, habitual soft contact lenses. A four-alternative forced-choice task in which the subject was to determine the location of the phase-shifting Gabor from the four quadrants (superior, inferior, nasal, and temporal) of the visual field, was employed. The experiment was blocked by eccentricity (20° and 27°), spatial frequency (0.6, 1.2, 2.4, and 4.0 cycles per degree (c/d) for 20° eccentricity, and 0.6, 1.2, 2.0, and 3.2 c/d for 27° eccentricity), as well as the motion speed [2 and 6 degree per second (d/s)].ResultsMixed-model analysis of variances showed no significant difference in the thresholds of peripheral motion detection between three refractive groups at either 20° (F[2,14] = 0.145, p = 0.866) or 27° (F[2,14] = 0.475, p = 0.632). At 20°, lower motion detection thresholds were associated with higher myopia (p < 0.05) mostly for low spatial frequency and high-speed targets in the nasal and superior quadrants, and for high spatial frequency and high-speed targets in the temporal quadrant in myopic viewers. Whereas at 27°, no significant correlation was found between the spherical equivalent and the peripheral motion detection threshold under all conditions (all p > 0.1). Spatial frequency, speed, and quadrant of the visual field all showed significant effect on the peripheral motion detection threshold.ConclusionThere was no significant difference between the three refractive groups in peripheral motion detection. However, lower motion detection thresholds were associated with higher myopia, mostly for low spatial frequency targets, at 20° in myopic viewers.

Selective Adaptation to Low Spatial Frequencies Does Not Decrease the Mueller-Lyer Illusion

1994 ◽  
Vol 78 (1) ◽  
pp. 339-347
Author(s):  
Janet D. Larsen ◽  
Beth Anne Goldstein
Keyword(s):  
Spatial Frequency ◽  
Visual System ◽  
Major Part ◽  
Selective Adaptation ◽  
Sinusoidal Grating ◽  
Square Wave ◽  
Frequency Information ◽  
Lyer Illusion ◽  
Spatial Frequencies

The idea that low spatial-frequency information in the Mueller-Lyer figure accounts for a major part of the illusion was tested in a series of five studies. In Study 1, subjects were selectively adapted to high or low square-wave spatial-frequency gratings with no difference in the magnitude of illusion they experienced. Similarly, adaptation to sinusoidal grating patterns with either high or low spatial frequency had no effect on the magnitude of illusion experienced (Studies 2 to 5). The failure of adaptation to low spatial-frequency gratings to affect the magnitude of illusion experienced indicates either that the illusion cannot be accounted for by the low spatial-frequency information or that adaptation of the visual system by grating patterns cannot be used to explore any effects of the low spatial frequencies in the figure.

Dark Adaptation as a Model of the Parkinsonian Visual System

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 48-48
Author(s):  
B Wink ◽  
J P Harris
Keyword(s):  
Spatial Frequency ◽  
Visual System ◽  
Dark Adaptation ◽  
Peripheral Vision ◽  
Receptive Fields ◽  
High Spatial Frequency ◽  
Normal Subjects ◽  
Apparent Contrast ◽  
Contrast Gain ◽  
Spatial Frequencies

It has been suggested that the Parkinsonian visual system is like the normal visual system, but is inappropriately dark-adapted (Beaumont et al, 1987 Clinical Vision Sciences2 123 – 129). Thus it is of interest to ask to what extent dark adaptation of normal subjects produces visual changes like those of Parkinson's disease (PD). One such change is the reduction in apparent contrast of medium and high spatial frequencies in peripheral vision in the illness (Harris et al, 1992 Brain115 1447 – 1457). Normal subjects judged whether the contrast of a peripherally viewed grating was higher or lower than that of a foveally viewed grating, and a staircase technique was used to estimate the point of subjective equality. Judgements were made at four spatial frequencies (0.5 to 4.0 cycles deg−1) and four contrasts (8.0% to 64%). The display, the mean luminance of which was 26 cd m−2, was viewed through a 1.5 lu nd filter in the relatively dark-adapted condition. The ANOVA showed an interaction between dark adaptation and the spatial frequency of the gratings. Dark adaptation reduces the apparent contrast of high-spatial-frequency gratings, an effect which is greater at lower contrasts. This mimics the effect found with PD sufferers, and suggests that dark adaptation may provide a useful model of the PD visual system. In a second experiment, the effect of dark adaptation on the relationship between apparent spatial frequency in the fovea and periphery was investigated. The experiment was similar to the first, except that judgements were made about the apparent spatial frequency, rather than the contrast, of the peripheral grating. ANOVA showed no differential effect of dark adaptation on the apparent spatial frequency of the peripheral grating. This suggests that the observed reduction in apparent contrast of the peripheral gratings in dark-adapted normals and Parkinson's sufferers may reflect relative changes in contrast gain, rather than relative changes in the spatial organisation of receptive fields.

Pretectal Neurons Optimized for the Detection of Saccade-Like Movements of the Visual Image

2001 ◽  
Vol 85 (4) ◽  
pp. 1512-1521 ◽  
Author(s):  
N.S.C. Price ◽  
M. R. Ibbotson
Keyword(s):  
Spatial Frequency ◽  
Second Harmonic ◽  
Temporal Frequency ◽  
Receptive Fields ◽  
High Spatial Frequency ◽  
Sine Wave ◽  
Wide Field ◽  
Visual Response ◽  
High Contrast ◽  
Sine Wave Gratings

The visual response properties of nondirectional wide-field sensitive neurons in the wallaby pretectum are described. These neurons are called scintillation detectors (SD-neurons) because they respond vigorously to rapid, high contrast visual changes in any part of their receptive fields. SD-neurons are most densely located within a 1- to 2-mm radius from the nucleus of the optic tract, interspersed with direction-selective retinal slip cells. Receptive fields are monocular and cover large areas of the contralateral visual field (30–120°). Response sizes are equal for motion in all directions, and spontaneous activities are similar for all orientations of static sine-wave gratings. Response magnitude increases near linearly with increasing stimulus diameter and contrast. The mean response latency for wide-field, high-contrast motion stimulation was 43.4 ± 9.4 ms (mean ± SD, n = 28). The optimum visual stimuli for SD-neurons are wide-field, low spatial frequency (<0.2 cpd) scenes moving at high velocities (75–500°/s). These properties match the visual input during saccades, indicating optimal sensitivity to rapid eye movements. Cells respond to brightness increments and decrements, suggesting inputs from on and off channels. Stimulation with high-speed, low spatial frequency gratings produces oscillatory responses at the input temporal frequency. Conversely, high spatial frequency gratings give oscillations predominantly at the second harmonic of the temporal frequency. Contrast reversing sine-wave gratings elicit transient, phase-independent responses. These responses match the properties of Y retinal ganglion cells, suggesting that they provide inputs to SD-neurons. We discuss the possible role of SD-neurons in suppressing ocular following during saccades and in the blink or saccade-locked modulation of lateral geniculate nucleus activity to control retino-cortical information flow.

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.

Predictions of U-Shaped Backward Pattern Masking from Considerations of the Spatio-Temporal Frequency Response

Perception ◽  
1975 ◽  
Vol 4 (3) ◽  
pp. 297-304 ◽  
Author(s):  
Bruno G Breitmeyer
Keyword(s):  
Spatial Frequency ◽  
Temporal Frequency ◽  
High Spatial Frequency ◽  
Stimulus Onset ◽  
Masking Effect ◽  
Time Interval ◽  
Sinusoidal Grating ◽  
Frequency Content ◽  
Pattern Masking ◽  
Spatio Temporal

The threshold detectability of a briefly presented target stimulus consisting of a vertical sinusoidal grating was affected not only by the spatial frequency content of an equally briefly presented, two-octave-wide masking noise, but also by the time interval separating the onsets of the target and its mask. Over a range of stimulus onset asynchronies, in which the mask onset either preceded, coincided with, or followed the target onset, a mask with a low spatial frequency content had its greatest masking effect on a high spatial frequency target grating when the mask followed the target by 120–180 ms. When the mask had a high spatial frequency content and the target was of low spatial frequency, or when the target was entered on the mask frequency band, optimal masking effects occurred when the onsets of the mask and target coincided. The results are discussed in relation to previous masking studies, particuarly those in which U-shaped backward pattern masking functions are obtained.

Spatial-Frequency Masking with Briefly Pulsed Patterns

Perception ◽  
1978 ◽  
Vol 7 (2) ◽  
pp. 161-166 ◽  
Author(s):  
Gordon E Legge ◽  
Michael A Cohen ◽  
Charles F Stromeyer
Keyword(s):  
Spatial Frequency ◽  
Frequency Band ◽  
Nonlinear Distortion ◽  
Test Pattern ◽  
Low Frequency ◽  
High Spatial Frequency ◽  
Sinusoidal Grating ◽  
Backward Masking ◽  
Frequency Test ◽  
Test Grating

Spatial-frequency masking was studied with briefly pulsed (25 ms) vertical gratings. The mask was a noise grating, and the test pattern was a sinusoidal grating. A low-frequency band of noise masked a low- but not high-spatial-frequency test grating when the patterns were presented simultaneously. A high-frequency band of noise did not mask a low-frequency test grating when the patterns were presented simultaneously or when the mask was presented after the test pattern (backward masking). Masking was, however, observed when the mask or test pattern was of sufficiently high contrast so that the stimuli had nonlinear distortion and thus produced DC shifts of the field luminance.

Recognition of Positive and Negative Bandpass-Filtered Images

Perception ◽  
1986 ◽  
Vol 15 (5) ◽  
pp. 595-602 ◽  
Author(s):  
Tony Hayes ◽  
M Concetta Morrone ◽  
David C Burr
Keyword(s):  
Spatial Frequency ◽  
Visual System ◽  
Visual Information ◽  
Recognition Performance ◽  
Low Frequency ◽  
High Spatial Frequency ◽  
Spatial Frequencies ◽  
Negative Images ◽  
Frequency Components

A study is reported in which the significance for vision of low- and high-spatial-frequency components of photographic positive and negative images was investigated by measuring recognition of bandpass-filtered photographs of faces. The results show that a 1.5 octave bandpass-filtered image contains sufficient visual information for good recognition performance, provided the filter is centred close to 20 cycles facewidth−1. At low spatial frequencies negatives are more difficult to recognize than positives, but at high spatial frequencies there is no difference in recognition, implying that it is the low-frequency components of negatives which present difficulties for the visual system.

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