Centre-Surround Tuning of Orientation Detectors in Human Vision

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 326-326 ◽  
Author(s):  
D L Ringach ◽  
R Shapley
Keyword(s):  
Presentation Rate ◽  
Stimulus Sequence ◽  
Human Vision ◽  
Orientation Tuning ◽  
Psychophysical Method ◽  
Circular Aperture ◽  
Spatial Frequencies ◽  
Mexican Hat ◽  
Horizontal Grating ◽  
Orientation Domain

We present a new psychophysical method to study the tuning of orientation detectors in the human visual system. The stimulus consists of a sequence of sinusoidal gratings of random orientations and spatial phases (but of fixed spatial frequency) shown at a high presentation rate (30 Hz) in 60 s long trials. The gratings are seen through a circular aperture. The subject's task is to report, as fast as possible, by pressing a key, when the presence of a horizontal grating is seen embedded in the stimulus sequence. The data are analysed by calculating the distribution of orientations present in the stimulus sequence at different times [before] the key was pressed. Similar experiments can be done by asking the subject to detect vertical and oblique orientations. In these experiments we used 100% contrast, a 3 deg diameter circular aperture, and spatial frequencies ranging from 1 to 4 cycles deg−1. The resulting orientation-tuning profiles have a ‘centre—surround’ (or Mexican hat) shape in the orientation domain. These findings are consistent with the idea of fast ‘lateral inhibition’ between orientation detectors. The centre—surround profiles may explain systematic errors in visual angle judgments, such as the perceptual expansion of acute angles and the contraction of obtuse angles, the tilt aftereffect, and the effects observed in the Zöllner, Hering, Ponzo, and Poggendorff illusions.

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.

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.

scholarly journals The Initial Disparity Vergence Elicited With Single and Dual Grating Stimuli in Monkeys: Evidence for Disparity Energy Sensing and Nonlinear Interactions

2008 ◽  
Vol 100 (5) ◽  
pp. 2907-2918 ◽  
Author(s):  
K. Miura ◽  
Y. Sugita ◽  
K. Matsuura ◽  
N. Inaba ◽  
K. Kawano ◽  
...  
Keyword(s):  
Sine Wave ◽  
Nonlinear Dependence ◽  
One Dimensional ◽  
Quarter Wavelength ◽  
Spatial Frequencies ◽  
Energy Sensing ◽  
The One ◽  
Winner Take All ◽  
Lower Contrast ◽  
Horizontal Grating

We recorded the initial vertical vergence eye movements elicited in monkeys at short latency (∼70 ms) when the two eyes see one-dimensional (1D) horizontal grating patterns that are identical except for a phase difference (disparity) of one-quarter wavelength. With gratings composed of single sine waves, responses were always compensatory, showing Gaussian dependence on log spatial frequency (on average: peak = 0.75 cycles/deg; SD = 0.74; r2 = 0.980) and monotonic dependence on log contrast with a gradual saturation well described by the Naka-Rushton equation (on average: n = 0.89; C50 = 4.1%; r2 = 0.978). With gratings composed of two sine waves whose spatial frequencies were in the ratio 3:5 and whose disparities were of opposite sign (the 3f5f stimulus), responses were determined by the disparities and contrasts of the two sine-wave components rather than the disparity of the features, consistent with early spatial filtering of the monocular inputs before their binocular combination and mediation by detectors sensitive to disparity energy. In addition, responses to the 3f5f stimulus showed a nonlinear dependence on the relative contrasts of the two sine waves. Thus on average, when the contrast of one sine wave was 2.3 times greater than that of the other, the one with the lower contrast was largely ineffective as though suppressed, and responses were determined almost entirely by the sine wave of higher contrast: Winner-Take-All. These findings are very similar to those published previously on the vertical vergence responses of humans, indicating that the monkey provides a good animal model for studying these disparity vergence responses.

Spatio-Chromatic Information Content of Natural Scenes

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 162-162 ◽  
Author(s):  
T Troscianko ◽  
C A Parraga ◽  
G Brelstaff ◽  
D Carr ◽  
K Nelson
Keyword(s):  
Spatial Frequency ◽  
Human Vision ◽  
Natural Scenes ◽  
Data Set ◽  
Frequency Space ◽  
Sensitivity Functions ◽  
Visual Encoding ◽  
Spatial Frequencies ◽  
Hyper Spectral ◽  
Fourier Spectra

A common assumption in the study of the relationship between human vision and the visual environment is that human vision has developed in order to encode the incident information in an optimal manner. Such arguments have been used to support the 1/f dependence of scene content as a function of spatial frequency. In keeping with this assumption, we ask whether there are any important differences between the luminance and (r/g) chrominance Fourier spectra of natural scenes, the simple expectation being that the chrominance spectrum should be relatively richer in low spatial frequencies than the luminance spectrum, to correspond with the different shape of luminance and chrominance contrast sensitivity functions. We analysed a data set of 29 images of natural scenes (predominantly of vegetation at different distances) which were obtained with a hyper-spectral camera (measuring the scene through a set of 31 wavelength bands in the range 400 – 700 nm). The images were transformed to the three Smith — Pokorny cone fundamentals, and further transformed into ‘luminance’ (r+g) and ‘chrominance’ (r-g) images, with various assumptions being made about the relative weighting of the r and g components, and the form of the chrominance response. We then analysed the Fourier spectra of these images using logarithmic intervals in spatial frequency space. This allowed a determination of the total energy within each Fourier band for each of the luminance and chrominance representations. The results strongly indicate that, for the set of scenes studied here, there was no evidence of a predominance of low-spatial-frequency chrominance information. Two classes of explanation are possible: (a) that raw Fourier content may not be the main organising principle determining visual encoding of colour, and/or (b) that our scenes were atypical of what may have driven visual evolution. We present arguments in favour of both of these propositions.

Managing Level of Detail in Virtual Environments: A Perceptual Framework

1997 ◽  
Vol 6 (6) ◽  
pp. 658-666 ◽  
Author(s):  
Martin Reddy ◽  
Benjamin Watson ◽  
Neff Walker ◽  
Larry F. Hodges
Keyword(s):  
Virtual Environments ◽  
Visual Information ◽  
Companion Paper ◽  
Sensitivity Function ◽  
Level Of Detail ◽  
Human Vision ◽  
Immersive Virtual Reality ◽  
Visual Change ◽  
Visual Detail ◽  
Spatial Frequencies

In the companion paper, Watson et al. (1997), we demonstrated the effectiveness of using perceptual criteria to select the amount of detail that is displayed in an immersive virtual reality (VR) system. Based upon this determination, we will now attempt to develop a principled, perceptually oriented framework to automatically select the appropriate level of detail (LOD) for each object in a scene, taking into consideration the limitations of the human visual system. We apply knowledge and theories from the domain of visual perception to the field of VR, thus optimizing the visual information presented to the user based upon solid metrics of human vision. Through a series of contrast grating experiments, a user's visual acuity may be assessed in terms of spatial frequency (c/deg) and contrast. The results of these tests can be modeled mathematically using a contrast sensitivity function (CSF). Therefore, we can use the CSF results to estimate how much visual detail the user can perceive in an object at any instant. Then, if we could describe this object in terms of its spatial frequencies, this would enable us to select the lowest LOD available without the user being able to perceive any visual change.

scholarly journals The representational dynamics of visual objects in rapid serial visual processing streams

2018 ◽  
Author(s):  
Tijl Grootswagers ◽  
Amanda K. Robinson ◽  
Thomas A. Carlson
Keyword(s):  
Visual Processing ◽  
Temporal Dynamics ◽  
Target Selection ◽  
Presentation Rate ◽  
Stimulus Presentation ◽  
Human Vision ◽  
Object Representations ◽  
Daily Lives ◽  
Multivariate Pattern ◽  
Rapid Serial Visual Processing

AbstractIn our daily lives, we are bombarded with a stream of rapidly changing visual input. Humans have the remarkable capacity to detect and identify objects in fast-changing scenes. Yet, when studying brain representations, stimuli are generally presented in isolation. Here, we studied the dynamics of human vision using a combination of fast stimulus presentation rates, electroencephalography and multivariate decoding analyses. Using a presentation rate of 5 images per second, we obtained the representational structure of a large number of stimuli, and showed the emerging abstract categorical organisation of this structure. Furthermore, we could separate the temporal dynamics of perceptual processing from higher-level target selection effects. In a second experiment, we used the same paradigm at 20Hz to show that shorter image presentation limits the categorical abstraction of object representations. Our results show that applying multivariate pattern analysis to every image in rapid serial visual processing streams has unprecedented potential for studying the temporal dynamics of the structure of representations in the human visual system.

scholarly journals Training for object recognition with increasing spatial frequency: A comparison of deep learning with human vision

2021 ◽  
Author(s):  
Lev Kiar Avberšek ◽  
Astrid Zeman ◽  
Hans P. Op de Beeck
Keyword(s):  
Spatial Frequency ◽  
Poor Performance ◽  
Visual Input ◽  
Human Vision ◽  
Striking Similarity ◽  
Deep Convolutional Neural Networks ◽  
Frequency Information ◽  
Spatial Frequencies ◽  
Wide Range ◽  
Coarse To Fine

AbstractThe ontogenetic development of human vision, and the real-time neural processing of visual input, both exhibit a striking similarity – a sensitivity towards spatial frequencies that progress in a coarse-to-fine manner. During early human development, sensitivity for higher spatial frequencies increases with age. In adulthood, when humans receive new visual input, low spatial frequencies are typically processed first before subsequently guiding the processing of higher spatial frequencies. We investigated to what extent this coarse-to-fine progression might impact visual representations in artificial vision and compared this to adult human representations. We simulated the coarse-to-fine progression of image processing in deep convolutional neural networks (CNNs) by gradually increasing spatial frequency information during training. We compared CNN performance, after standard and coarse-to-fine training, with a wide range of datasets from behavioural and neuroimaging experiments. In contrast to humans, CNNs that are trained using the standard protocol are very insensitive to low spatial frequency information, showing very poor performance in being able to classify such object images. By training CNNs using our coarse-to-fine method, we improved the classification accuracy of CNNs from 0% to 32% on low-pass filtered images taken from the ImageNet dataset. When comparing differently trained networks on images containing full spatial frequency information, we saw no representational differences. Overall, this integration of computational, neural, and behavioural findings shows the relevance of the exposure to and processing of input with a variation in spatial frequency content for some aspects of high-level object representations.

Suprathreshold Contrast Increment Detection is not Affected by Grating Edge-Type

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 271-271
Author(s):  
D R Melmoth ◽  
H T Kukkonen
Keyword(s):  
Fourier Spectrum ◽  
Sinusoidal Grating ◽  
Circular Aperture ◽  
Edge Type ◽  
Spatial Frequencies ◽  
Significant Difference ◽  
Affect Detection ◽  
Sinusoidal Gratings ◽  
Frequency Components ◽  
Subject Performance

We have shown that the spatial frequency components introduced by sharply truncating the edge of a sinusoidal grating do not affect detection thresholds (Kukkonen et al, 1996 Perception25 Supplement, 117). This could be due to the fact that contrast energy at these spatial frequencies is much lower than at the nominal frequency. Any effect upon detection attributable to the broadening of the Fourier spectrum might therefore exert itself most strongly at suprathreshold rather than threshold contrast levels. To establish whether these extra components interfere with performance at higher contrasts, we measured contrast increment thresholds of circular-aperture sinusoidal gratings with a pedestal contrast of 0.5. Gratings were either sharply truncated or Gaussian-edged having a half-contrast diameter equal to that of its corresponding sharp-edged stimulus. Gratings of 0.125 and 0.5 cycle deg−1 were used, each tested with 1 – 8 cycles. There was no significant difference between contrast increment thresholds for the sharp-edged and Gaussian-edged gratings, which were spectrally narrower. The frequency components introduced into the Fourier spectrum by the abrupt edge of the truncated gratings appear to have no effect upon subject performance even in suprathreshold contrast increment detection.

Monocular and binocular response properties of cells in the striate-recipient zone of the cat's lateral posterior-pulvinar complex

1989 ◽  
Vol 62 (2) ◽  
pp. 544-557 ◽  
Author(s):  
C. Casanova ◽  
R. D. Freeman ◽  
J. P. Nordmann
Keyword(s):  
Spatial Frequency ◽  
Frequency Tuning ◽  
Single Cells ◽  
Temporal Frequency ◽  
Orientation Tuning ◽  
Low Frequencies ◽  
Response Properties ◽  
Spatial Frequencies ◽  
Lateral Posterior ◽  
The Mean

1. We have studied response properties of single cells in the striate-recipient zone of the cat's lateral posterior-pulvinar (LP-P) complex. This zone is in the lateral section of the lateral posterior nucleus (LP1). Our purpose was to determine basic response characteristics of these cells and to investigate the possibility that the LP-P complex is a center of integration that is dominated by input from visual cortex. 2. The majority (72%) of cells in the striate-recipient zone respond to drifting sinusoidal gratings with unmodulated discharge. 3. Cells in the LP1 are selective to the orientation of gratings, and tuning functions have a mean bandwidth of 31 degrees. More than one-half of these units are direction-selective. The preferred orientation and the tuning widths for the two eyes are generally well matched. However, a few cells exhibited the interesting property of opposite preferred directions for the two eyes. Orientation tuning for a small group of cells was different for the mean discharge and first harmonic components, suggesting a convergence from different inputs to these cells. 4. Two-thirds of LP1 cells are tuned to low spatial frequencies (less than 0.5 c/deg). The tuning is broad with a mean bandwidth of 2.2 octaves. The remaining one-third of the units are low-pass because they show no attenuation of their responses to low spatial frequencies. Both eyes exhibit the same spatial frequency preference and the same spatial frequency tuning. There is a high correlation between spatial frequency and orientation selectivities. 5. All cells tested are tuned for temporal frequency with a sharp attenuation for low frequencies. The optimal values range between 4 and 8 Hz, and the mean bandwidth is 2.2 octaves. 6. Cells in LP1 are mostly binocular. When monocular, cells are almost always contralaterally driven. Dichoptic presentation of gratings reveals the presence of strong binocular interaction. In almost all cases, these interactions are phase specific. The cell's discharge is facilitated at particular phases and inhibited at phases 180 degrees away. These binocular interactions are orientation dependent. 7. Twenty-five percent of the cells with phase-specific binocular facilitation appear to be monocular when each eye is tested separately. For three cells, we observed a non-phase-specific inhibitory effect of the silent eye. 8. Our findings indicate that LP1 cells form a relatively homogeneous group, suggesting a high degree of integration of multiple cortical inputs.(ABSTRACT TRUNCATED AT 400 WORDS)

Are Curves Detected by ‘Curvature Detectors’?

Perception ◽  
1978 ◽  
Vol 7 (1) ◽  
pp. 51-64 ◽  
Author(s):  
Brian N Timney ◽  
Colin Macdonald
Keyword(s):  
Visual System ◽  
Human Visual System ◽  
Human Vision ◽  
Orientation Tuning ◽  
Threshold Elevation ◽  
Maximum Value ◽  
Adaptation Experiment ◽  
The Relationship

Five experiments which attempted to evaluate the relationship between orientation and curvature selectivity in human vision are described. In the first two experiments, threshold elevation for curved gratings was measured after exposure to similar gratings, with the use of either an adaptation (experiment 1) or a masking (experiment 2) paradigm. In both experiments threshold elevation occurred which was selective for both the degree and the direction of curvature of the adapting pattern. Experiment 3 compared the effects of adapting to tilted rectilinear or vertical curved gratings upon threshold for a vertical rectilinear grating. Threshold elevation declined systematically as the adapting gratings were either tilted or made more curved. Experiment 4 measured curvature selectivity as a function of the orientation of a curved adapting grating. Threshold elevation declined as the adapting grating was tilted more, but curvature selectivity remained. Experiment 5 measured the orientation tuning for curved gratings directly. Threshold elevation declined to 50% of its maximum value at an adapting orientation of about 28°. This was constant for all values of curvature used. The results are discussed with reference to the question of whether the human visual system contains ‘curvature detectors’ or linear-contour detectors which respond to the tangents of curves.

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