Ghost imaging of the low or high frequency based on the corresponding spatial-frequency of the reference pattern

The aim of the experiments was to discover whether the visual system has independent access to motion information at different spatial scales when presented with a broadband stimulus. Subjects were required to discriminate between a pair of two-frame motion sequences, one containing a coherently displacing pattern and the other containing a pattern with high-frequency noise. The stimuli were either narrowband (1 octave) or broadband (6 octaves spanning 0.23–15.0 cycles deg−1) and their power spectra were either flat or followed a 1 /f2 function. For the broadband stimuli, noise was introduced cumulatively into increasingly lower frequencies. For the narrowband stimuli, noise was introduced into the same frequency band as the signal. All stimuli could be defined by the lowest noise frequency ( n1) they contained. For each stimulus, the largest spatial displacement across the two frames at which the task could be performed was measured ( dmax). For the narrowband stimuli, dmax increased as n1 was lowered. This was true over the entire frequency range for the 1 /f2 stimuli, though the task became impossible for the flat-spectrum stimuli at the lowest frequencies. This is attributed to the very low contrast of these latter stimuli. The dmax values for the broadband stimuli tended to shadow those of the narrowband stimuli with the equivalent values of n1 being around 25% lower. The data were modelled by spatiotemporally filtering the stimuli and considering the amount of directional power in the signal and noise sequences. The results suggest that there must be multiple spatial-frequency channels in operation, and that for broadband patterns the visual system has perceptual access to these individual channel outputs, utilising different filters depending on the task requirements.

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Disparity Modulation Sensitivity for Narrow-Band-Filtered Stereograms Viewed out of the Plane of Fixation

Perception ◽

10.1068/v96p0206 ◽

1996 ◽

Vol 25 (1_suppl) ◽

pp. 94-94

Author(s):

B Lee ◽

B J Rogers

Keyword(s):

Spatial Frequency ◽

High Frequency ◽

Significant Interaction ◽

Narrow Band ◽

Low Frequency ◽

Frequency Pattern ◽

Spatial Frequencies ◽

Size Disparity ◽

Random Dot Stereograms

Narrow-band-filtered random-dot stereograms were used to determine stereo thresholds for detecting sinusoidal disparity modulations. These stereograms were designed to stimulate selectively channels tuned to luminance and corrugation spatial frequencies (Schumer and Ganz, 1979 Vision Research19 1303 – 1314). Thresholds were determined for corrugation frequencies ranging from 0.125 to 1 cycle deg−1, luminance centre spatial frequencies ranging from 1 to 8 cycles deg−1 and disparity pedestal sizes ranging from −32 to +32 min arc. For small disparity pedestals, lowest modulation thresholds were found around 0.5 cycle deg−1 corrugation frequency and 4 cycles deg−1 luminance centre spatial frequency. For large disparity pedestals (±32 arc min), lowest thresholds were shifted towards the lower corrugation frequencies (0.125 cycle deg−1) and lower luminance frequencies (2 cycles deg−1). There was a significant interaction between luminance spatial frequency and disparity pedestal size. For small pedestals, lowest thresholds were found with the highest luminance frequency pattern (4 cycles deg−1). For large pedestals, best performance shifted towards the low-frequency patterns (1 cycle deg−1). This effect demonstrates a massive reduction in stereo-efficiency for high-frequency patterns in the luminance domain at large disparity pedestals which is consistent with the ‘size-disparity relation’ proposed by previous researchers.

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Transfer of Learning in Transformed Random-Dot Stereostimuli

Perception ◽

10.1068/p110409 ◽

1982 ◽

Vol 11 (4) ◽

pp. 409-414 ◽

Cited By ~ 2

Author(s):

Nigel R Long

Keyword(s):

Spatial Frequency ◽

High Frequency ◽

Transfer Of Learning ◽

Low Frequency ◽

Frequency Characteristics ◽

Frequency Transformations

The transfer of learning between normal and monocularly-transformed small-disparity, random-dot stereostimuli has been examined under extended viewing conditions. When the disparity value was constant, transfer of learning between normal and monocularly-transformed stereostimuli was disrupted by both low-frequency and high-frequency transformations. These results suggest that stereolearning is restricted to disparity units that are selective to the same spatial-frequency characteristics.

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Spatial Scale Interactions and Visual-Tracking Performance

Perception ◽

10.1068/p261047 ◽

1997 ◽

Vol 26 (8) ◽

pp. 1047-1058 ◽

Cited By ~ 1

Author(s):

Howard C Hughes ◽

David M Aronchick ◽

Michael D Nelson

Keyword(s):

Spatial Frequency ◽

High Frequency ◽

Visual Information ◽

Low Frequency ◽

High Spatial Frequency ◽

Performance Measure ◽

High Frequency Component ◽

Stimulus Velocity ◽

Spatial Frequencies ◽

Wide Range

It has previously been observed that low spatial frequencies (≤ 1.0 cycles deg−1) tend to dominate high spatial frequencies (≥ 5.0 cycles deg−1) in several types of visual-information-processing tasks. This earlier work employed reaction times as the primary performance measure and the present experiments address the possibility of low-frequency dominance by evaluating visually guided performance of a completely different response system: the control of slow-pursuit eye movements. Slow-pursuit gains (eye velocity/stimulus velocity) were obtained while observers attempted to track the motion of a sine-wave grating. The drifting gratings were presented on three types of background: a uniform background, a background consisting of a stationary grating, or a flickering background. Low-frequency dominance was evident over a wide range of velocities, in that a stationary high-frequency component produced little disruption in the pursuit of a drifting low spatial frequency, but a stationary low frequency interfered substantially with the tracking of a moving high spatial frequency. Pursuit was unaffected by temporal modulation of the background, suggesting that these effects are due to the spatial characteristics of the stationary grating. Similar asymmetries were observed with respect to the stability of fixation: active fixation was less stable in the presence of a drifting low frequency than in the presence of a drifting high frequency.

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Spatial Frequency Tuning and Transfer of Perceptual Learning for Motion Coherence Reflects the Tuning Properties of Global Motion Processing

Vision ◽

10.3390/vision3030044 ◽

2019 ◽

Vol 3 (3) ◽

pp. 44 ◽

Cited By ~ 1

Author(s):

Jordi Asher ◽

Vincenzo Romei ◽

Paul Hibbard

Keyword(s):

Spatial Frequency ◽

Perceptual Learning ◽

Contrast Sensitivity ◽

High Frequency ◽

Frequency Tuning ◽

Low Frequency ◽

Motion Processing ◽

Global Motion ◽

Low Frequencies ◽

Motion Coherence

Perceptual learning is typically highly specific to the stimuli and task used during training. However, recently, it has been shown that training on global motion can transfer to untrained tasks, reflecting the generalising properties of mechanisms at this level of processing. We investigated (i) if feedback was required for learning in a motion coherence task, (ii) the transfer across the spatial frequency of training on a global motion coherence task and (iii) the transfer of this training to a measure of contrast sensitivity. For our first experiment, two groups, with and without feedback, trained for ten days on a broadband motion coherence task. Results indicated that feedback was a requirement for robust learning. For the second experiment, training consisted of five days of direction discrimination using one of three motion coherence stimuli (where individual elements were comprised of either broadband Gaussian blobs or low- or high-frequency random-dot Gabor patches), with trial-by-trial auditory feedback. A pre- and post-training assessment was conducted for each of the three types of global motion coherence conditions and high and low spatial frequency contrast sensitivity (both without feedback). Our training paradigm was successful at eliciting improvement in the trained tasks over the five days. Post-training assessments found evidence of transfer for the motion coherence task exclusively for the group trained on low spatial frequency elements. For the contrast sensitivity tasks, improved performance was observed for low- and high-frequency stimuli, following motion coherence training with broadband stimuli, and for low-frequency stimuli, following low-frequency training. Our findings are consistent with perceptual learning, which depends on the global stage of motion processing in higher cortical areas, which is broadly tuned for spatial frequency, with a preference for low frequencies.

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Delineating the low and high spatial frequency inputs to face perception using transcranial random noise stimulation

10.31234/osf.io/t7dps ◽

2020 ◽

Author(s):

Bhuvanesh Awasthi

Keyword(s):

Spatial Frequency ◽

High Frequency ◽

Response Times ◽

Random Noise ◽

Temporal Cortex ◽

High Spatial Frequency ◽

Bayesian Approaches ◽

Frequency Information ◽

Transcranial Random Noise Stimulation ◽

The Right

This study used high frequency transcranial Random Noise Stimulation (tRNS) to examine how low and high spatial frequency filtered faces are processed. In a response time behavioral task, healthy young adults categorized male and female faces, presented at fovea and periphery in alternate blocks, while sham and high frequency random noise was applied to occipito-parietal location on their scalp. Both the frequentist and bayesian approaches show that stimulation at the right occipito-temporal cortex significantly reduced response times to peripherally presented low spatial frequency information. This finding points to a possible plasticity in targeted regions induced by non-invasive neuromodulation of spatial frequency information in rapid perception of faces.

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Регистрация высокочастотных рельефно-фазовых голографических структур на фотоматериале ПФГ-04

Письма в журнал технической физики ◽

10.21883/pjtf.2021.21.51621.18941 ◽

2021 ◽

Vol 47 (21) ◽

pp. 13

Author(s):

Н.М. Ганжерли ◽

С.Н. Гуляев ◽

И.А. Маурер ◽

А.В. Архипов

Keyword(s):

Spatial Frequency ◽

Uv Radiation ◽

Diffraction Efficiency ◽

High Frequency ◽

Short Wave ◽

Destructive Effect ◽

Holographic Gratings ◽

New Variant ◽

First Time ◽

Relief Phase

A new variant of processing photographic plates for holography based on dichromed gelatin PFG-04 (produced by JSC "Slavich Company", Pereslavl-Zalessky) for the manufacture of high-frequency relief–phase holographic gratings with a spatial frequency up to 1500 mm-1 is proposed. The technology is based on the selective destructive effect of short-wave UV radiation on gelatin and subsequent etching of the layer with various reagents. For the first time, relief-phase high-frequency holographic gratings with a maximum diffraction efficiency of 67% were obtained on PFG-04 photographic plates.

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Effect of repetitive visual stimuli on behaviour and plasma corticosterone of European starlings

Animal Biology ◽

10.1163/1570756054472827 ◽

2005 ◽

Vol 55 (3) ◽

pp. 245-258 ◽

Cited By ~ 3

Author(s):

◽

Keyword(s):

Spatial Frequency ◽

High Frequency ◽

Temporal Frequency ◽

Low Frequency ◽

High Spatial Frequency ◽

Plasma Corticosterone ◽

European Starlings ◽

Fluorescent Lamps ◽

Spatial Frequencies ◽

Temporal And Spatial

AbstractFlickering light can cause adverse effects in some humans, as can rhythmic spatial patterns of particular frequencies. We investigated whether birds react to the temporal frequency of standard 100 Hz fluorescent lamps and the spatial frequency of the visual surround in the manner predicted by the human literature, by examining their effects on the preferences, behaviour and plasma corticosterone of European starlings (Sturnus vulgaris). We predicted that high frequency lighting (> 30 kHz) and a relatively low spatial frequency on the walls of their cages (0.1 cycle cm−1) would be less aversive than low frequency lighting (100 Hz) and a relatively high spatial frequency (2.5 cycle cm−1). Birds had strong preferences for both temporal and spatial frequencies. These preferences did not always fit with predictions, although there was evidence that 100 Hz was more stressful than 30 kHz lighting, as birds were less active and basal corticosterone levels were higher under 100 Hz lighting. Our chosen spatial frequencies had no overall significant effect on corticosterone levels. Although there are clearly effects of, and interactions between, the frequency of the light and the visual surround on the behaviour and physiology of birds, the pattern of results is not straightforward.

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Diphasic and Polyphasic Temporal Modulations Multiply Apparent Spatial Frequency

Perception ◽

10.1068/p030323 ◽

1974 ◽

Vol 3 (3) ◽

pp. 323-336 ◽

Cited By ~ 21

Author(s):

V Virsu ◽

G Nyman ◽

P K Lehtiö

Keyword(s):

Spatial Frequency ◽

High Frequency ◽

Light Adaptation ◽

Second Harmonic ◽

Temporal Integration ◽

Low Frequency ◽

Integration Time ◽

Sinusoidal Grating ◽

Spatial Effects ◽

Spatial Integration

The effects of diphasic and polyphasic flicker on apparent spatial frequency were studied in several experiments through simultaneous spatial-frequency matches. In diphasic flicker the spatial phase of a sinusoidal grating alternated between two values in a counterphase fashion, and in polyphasic flicker the spatial phases of gratings were varied discretely in time in a variable number of steps. Both forms of flicker increased the apparent spatial frequency at low temporal frequencies, in the same manner as low-frequency monophasic flicker has been found to do. At high temporal frequencies, diphasic flicker doubled the apparent spatial frequency, as reported by Kelly (1966). We found that through high-frequency polyphasic flicker the spatial effect that Kelly mentions can be generalised to spatial frequency multiplication: polyphasic flicker produces not only the apparent second harmonic but also the third and the fourth harmonic, depending on the phase parameters. A numerical analysis showed that the spatial high-frequency effects can be explained through temporal integration of nonlinearly filtered input signals if a value of 200 td(1) is assumed for the nonlinearity constant in [Formula: see text] where B( I) is the brightness, I is the retinal illuminance, K is a scale constant, and I½ is the constant of nonlinearity. A minimum value of 60 ms had to be estimated for integration time. An investigation of the integration time with diphasic flicker indicated that spatial integration time decreases when the level of light adaptation increases, and that the integration time for spatial effects is longer than for flicker fusion. The spatial effects of low-frequency and high-frequency flicker differ in so many respects that different neural processes have to be postulated for their explanation.

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Global Precedence, Spatial Frequency Channels, and the Statistics of Natural Images

Journal of Cognitive Neuroscience ◽

10.1162/jocn.1996.8.3.197 ◽

1996 ◽

Vol 8 (3) ◽

pp. 197-230 ◽

Cited By ~ 168

Author(s):

Howard C. Hughes ◽

George Nozawa ◽

Frederick Kitterle

Keyword(s):

Spatial Frequency ◽

High Frequency ◽

Reaction Times ◽

Low Frequency ◽

Natural Images ◽

Visual Pattern ◽

Pattern Perception ◽

Global Precedence ◽

Processing Times ◽

Spatial Frequencies

A great deal of evidence suggests that early in processing, retinal images are filtered by parallel, spatial frequency selective channels. We attempt to incorporate this view of early vision with the principle of global precedence, which holds that Gestalt-like processes sensitive to global image configurations tend to dominate local feature processing in human pattern perception. Global precedence is inferred from the pattern of reaction times observed when visual patterns contain multiple cues at different levels of spatial scale. Specifically, it is frequently observed that global processing times are largely unaffected by conflicting local cues, but local processing times are substantially lengthened by conflicting global cues. The asymmetry of these effects suggests the dominant role of global configurations. Since global spatial information is effectively represented by low spatial frequencies, global precedence potentially implies a low frequency dominance. The thesis is that low spatial frequencies tend to be available before information carried by higher frequency bands, producing a coarse-to-fine temporal order in visual spatial perception. It is suggested that a variety of factors contribute to the “prior entry” of low frequency information, including the high contrast gain of the magnocellular pathway, the amplitude spectra typical of natural images, and inhibitory interactions between the parallel frequency-tuned channels. Evidence suggesting a close relationship between global precedence and spatial frequency channels is provided by observations that the essential features of the global precedence effect are obtained using patterns consisting of low and high frequency sinusoids. The hypothesis that these asymmetric interference effects are due to interactions between parallel spatial channels is supported by an analysis of reaction times (RTs), which shows that RTs to redundant low and high frequency cues produce less facilitation than predictions that assume the channels are independent. In view of previous work showing that global precedence depends upon the low frequency content of the stimuli, we suggest that low spatial frequencies represent the sine qua non for the dominance of configurational cues in human pattern perception, and that this configurational dominance reflects the microgenesis of visual pattern perception. This general view of the temporal dynamics of visual pattern recognition is discussed, is considered from an evolutionary perspective, and is related to certain statistical regularities in natural scenes. Potential adaptive advantages of an interactive parallel architecture that confers an initial processing advantage to low resolution information are explored.

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