scholarly journals Monocular blur alters the tuning characteristics of stereopsis for spatial frequency and size

2016 ◽  
Vol 3 (9) ◽  
pp. 160273 ◽  
Author(s):  
Roger W. Li ◽  
Kayee So ◽  
Thomas H. Wu ◽  
Ashley P. Craven ◽  
Truyet T. Tran ◽  
...  
Keyword(s):  
Spatial Frequency ◽  
Narrow Band ◽  
Frequency Tuning ◽  
Low Frequency ◽  
High Spatial Frequency ◽  
Spatial Filters ◽  
Optimum Frequency ◽  
Spatial Frequencies ◽  
Coarse To Fine ◽  
Tuning Function

Our sense of depth perception is mediated by spatial filters at different scales in the visual brain; low spatial frequency channels provide the basis for coarse stereopsis, whereas high spatial frequency channels provide for fine stereopsis. It is well established that monocular blurring of vision results in decreased stereoacuity. However, previous studies have used tests that are broadband in their spatial frequency content. It is not yet entirely clear how the processing of stereopsis in different spatial frequency channels is altered in response to binocular input imbalance. Here, we applied a new stereoacuity test based on narrow-band Gabor stimuli. By manipulating the carrier spatial frequency, we were able to reveal the spatial frequency tuning of stereopsis, spanning from coarse to fine, under blurred conditions. Our findings show that increasing monocular blur elevates stereoacuity thresholds ‘selectively’ at high spatial frequencies, gradually shifting the optimum frequency to lower spatial frequencies. Surprisingly, stereopsis for low frequency targets was only mildly affected even with an acuity difference of eight lines on a standard letter chart. Furthermore, we examined the effect of monocular blur on the size tuning function of stereopsis. The clinical implications of these findings are discussed.

Spatial-frequency and orientation tuning in psychophysical end-stopping

1998 ◽  
Vol 15 (4) ◽  
pp. 585-595 ◽  
Author(s):  
CONG YU ◽  
DENNIS M. LEVI
Keyword(s):  
Spatial Frequency ◽  
Frequency Tuning ◽  
Spatial Filter ◽  
Orientation Tuning ◽  
Maximal Strength ◽  
Facilitation Effect ◽  
Spatial Filters ◽  
Spatial Frequency Tuning ◽  
Spatial Frequencies ◽  
Wide Range

A psychophysical analog to cortical receptive-field end-stopping has been demonstrated previously in spatial filters tuned to a wide range of spatial frequencies (Yu & Levi, 1997a). The current study investigated tuning characteristics in psychophysical spatial filter end-stopping. When a D6 (the sixth derivative of a Gaussian) target is masked by a center mask (placed in the putative spatial filter center), two end-zone masks (placed in the filter end-zones) reduce thresholds. This “end-stopping” effect (the reduction of masking induced by end-zone masks) was measured at various spatial frequencies and orientations of end-zone masks. End-stopping reached its maximal strength when the spatial frequency and/or orientation of the end-zone masks matched the spatial frequency and/or orientation of the target and center mask, showing spatial-frequency tuning and orientation tuning. The bandwidths of spatial-frequency and orientation tuning functions decreased with increasing target spatial frequency. At larger orientation differences, however, end-zone masks induced a secondary facilitation effect, which was maximal when the spatial frequency of end-zone masks equated the target spatial frequency. This facilitation effect might be related to certain types of contour and texture perception, such as perceptual pop-out.

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

Perception ◽  
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.

Spatial Scale Interactions and Visual-Tracking Performance

Perception ◽  
1997 ◽  
Vol 26 (8) ◽  
pp. 1047-1058 ◽  
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.

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

2005 ◽  
Vol 55 (3) ◽  
pp. 245-258 ◽  
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.

The Neural Substrates and Timing of Top–Down Processes during Coarse-to-Fine Categorization of Visual Scenes: A Combined fMRI and ERP Study

2010 ◽  
Vol 22 (12) ◽  
pp. 2768-2780 ◽  
Author(s):  
Carole Peyrin ◽  
Christoph M. Michel ◽  
Sophie Schwartz ◽  
Gregor Thut ◽  
Mohamed Seghier ◽  
...  
Keyword(s):  
Spatial Frequency ◽  
Visual Analysis ◽  
High Spatial Frequency ◽  
Neural Substrates ◽  
Brain Network ◽  
Processing Scheme ◽  
Spatial Frequencies ◽  
Visual Areas ◽  
Initial Activation ◽  
Coarse To Fine

Spatial frequencies in an image influence visual analysis across a distributed, hierarchically organized brain network. Low spatial frequency (LSF) information may rapidly reach high-order areas to allow an initial coarse parsing of the visual scene, which could then be “retroinjected” through feedback into lower level visual areas to guide finer analysis on the basis of high spatial frequency (HSF). To test this “coarse-to-fine” processing scheme and to identify its neural substrates in the human brain, we presented sequences of two spatial-frequency-filtered scenes in rapid succession (LSF followed by HSF or vice versa) during fMRI and ERPs in the same participants. We show that for low-to-high sequences (but not for high-to-low sequences), LSF produces a first increase of activity in prefrontal and temporo-parietal areas, followed by enhanced responses to HSF in primary visual cortex. This pattern is consistent with retroactive influences on low-level areas that process HSF after initial activation of higher order areas by LSF.

scholarly journals Sharpening coarse-to-fine stereo vision by perceptual learning: asymmetric transfer across the spatial frequency spectrum

2016 ◽  
Vol 3 (1) ◽  
pp. 150523 ◽  
Author(s):  
Roger W. Li ◽  
Truyet T. Tran ◽  
Ashley P. Craven ◽  
Tsz-Wing Leung ◽  
Sandy W. Chat ◽  
...  
Keyword(s):  
Spatial Frequency ◽  
Perceptual Learning ◽  
Frequency Spectrum ◽  
Three Dimensional ◽  
High Spatial Frequency ◽  
Visual Image ◽  
Spatial Frequencies ◽  
Early Visual Cortex ◽  
Coarse To Fine ◽  
Spatial Frequency Spectrum

Neurons in the early visual cortex are finely tuned to different low-level visual features, forming a multi-channel system analysing the visual image formed on the retina in a parallel manner. However, little is known about the potential ‘cross-talk’ among these channels. Here, we systematically investigated whether stereoacuity, over a large range of target spatial frequencies, can be enhanced by perceptual learning. Using narrow-band visual stimuli, we found that practice with coarse (low spatial frequency) targets substantially improves performance, and that the improvement spreads from coarse to fine (high spatial frequency) three-dimensional perception, generalizing broadly across untrained spatial frequencies and orientations. Notably, we observed an asymmetric transfer of learning across the spatial frequency spectrum. The bandwidth of transfer was broader when training was at a high spatial frequency than at a low spatial frequency. Stereoacuity training is most beneficial when trained with fine targets. This broad transfer of stereoacuity learning contrasts with the highly specific learning reported for other basic visual functions. We also revealed strategies to boost learning outcomes ‘beyond-the-plateau’. Our investigations contribute to understanding the functional properties of the network subserving stereovision. The ability to generalize may provide a key principle for restoring impaired binocular vision in clinical situations.

Depth Interpolation with Sparse Disparity Cues

Perception ◽  
1989 ◽  
Vol 18 (1) ◽  
pp. 39-54 ◽  
Author(s):  
Sofia M Würger ◽  
Michael S Landy
Keyword(s):  
Spatial Frequency ◽  
Narrow Band ◽  
High Spatial Frequency ◽  
Linear Interpolation ◽  
Uniform Field ◽  
Frequency Content ◽  
Apparent Contrast ◽  
Spatial Frequencies ◽  
Basic Stimulus ◽  
Filtered Noise

The interpolation of stereoscopic depth given only sparse disparity information was investigated. The basic stimulus was a rectangle with zero disparity at one edge, and 20 or 30 min visual angle disparity at the other. The depth assigned to the ambiguous intervening locations was measured by means of a small briefly-flashed binocular comparison spot. For a stimulus consisting of a uniform rectangle presented on a background of random dots with zero disparity, interpolated depth was greater for a high mean contrast between rectangle and background than for a low mean contrast. Relative to a linear interpolation between the edges, a larger difference in edge disparity resulted in poorer depth interpolation. Depth interpolation based on rivalrous information was examined by filling the stimulus rectangle with narrow-band filtered noise which was uncorrelated between the two eyes. Four different passbands which were matched in apparent contrast were investigated. The results demonstrate that the rivalrous low-spatial-frequency content was resistant to interpolation; rivalrous high spatial frequencies did not interfere with depth interpolation. High-spatial-frequency stimuli yielded a percept similar to the uniform-field condition, whereas low-spatial-frequency stimuli lay in a depth plane near or even behind the background. In the latter case a transparent plane was perceived which was linearly interpolated between the two edges, and which floated above the rivalrous noise.

Vergence Eye Movements Made in Response to Spatial-Frequency-Filtered Random-Dot Stereograms

Perception ◽  
1981 ◽  
Vol 10 (3) ◽  
pp. 299-304 ◽  
Author(s):  
Peter Mowforth ◽  
John E W Mayhew ◽  
John P Frisby
Keyword(s):  
Eye Movements ◽  
Spatial Frequency ◽  
Stereo Vision ◽  
Narrow Band ◽  
High Spatial Frequency ◽  
Spatial Frequencies ◽  
Random Dot Stereograms ◽  
Made In

Vergence responses were recorded from practised observers viewing narrow-band spatial-frequency-filtered planar random-dot stereograms. It was found that low spatial frequencies of 1·75–3·5 cycles deg−1 could trigger appropriate vergence responses to larger disparities than could the relatively high spatial frequency of 7·0 cycles deg−1. Nevertheless, appropriate vergence shifts were observed reliably for spatial-frequency/disparity combinations well outside the range predicted by Marr and Poggio's (1979) model of stereo vision. It was also found that for large-disparity/high-spatial-frequency combinations which the subjects could not fuse, the vergence system went into oscillation with the eyes diverging and converging at a frequency of about 1·5 Hz and with an amplitude of about 10–20 min arc. Finally, it was demonstrated that when a prominent monocular cue was superimposed upon a large-disparity/high-spatial-frequency stereogram then a speedy vergence response occurred which resulted in successful fusion. This latter finding supports the hypothesis advanced earlier that monocular cues can facilitate stereopsis by triggering appropriate vergence shifts.

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.

scholarly journals Contrast thresholds reveal different visual masking functions in humans and praying mantises

2017 ◽  
Author(s):  
Ghaith Tarawneh ◽  
Vivek Nityananda ◽  
Ronny Rosner ◽  
Steven Errington ◽  
William Herbert ◽  
...  
Keyword(s):  
Spatial Frequency ◽  
Motion Detection ◽  
Visual Masking ◽  
High Spatial Frequency ◽  
Visual Noise ◽  
Frequency Noise ◽  
Detection Systems ◽  
Spatial Frequencies ◽  
Summary Statement ◽  
Contrast Thresholds

AbstractRecently, we showed a novel property of the Hassenstein-Reichardt detector: namely, that insect motion detection can be masked by “invisible” noise, i.e. visual noise presented at spatial frequencies to which the animals do not respond when presented as a signal. While this study compared the effect of noise on human and insect motion perception, it used different ways of quantifying masking in two species. This was because the human studies measured contrast thresholds, which were too time-consuming to acquire in the insect given the large number of stimulus parameters examined. Here, we run longer experiments in which we obtained contrast thresholds at just two signal and two noise frequencies. We examine the increase in threshold produced by noise at either the same frequency as the signal, or a different frequency. We do this in both humans and praying mantises (Sphodromantis lineola), enabling us to compare these species directly in the same paradigm. Our results confirm our earlier finding: whereas in humans, visual noise masks much more effectively when presented at the signal spatial frequency, in insects, noise is roughly equivalently effective whether presented at the same frequency or a lower frequency. In both species, visual noise presented at a higher spatial frequency is a less effective mask.Summary StatementWe here show that despite having similar motion detection systems, insects and humans differ in the effect of low and high spatial frequency noise on their contrast thresholds.

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