Pattern and Flicker Detection Examined in Terms of the Nasal — Temporal Division of the Retina

Perception ◽  
1979 ◽  
Vol 8 (5) ◽  
pp. 549-555 ◽  
Author(s):  
Randolph Blake ◽  
Jamie Mills
Keyword(s):  
Spatial Frequency ◽  
Hemispheric Asymmetries ◽  
Contrast Thresholds

Contrast thresholds for the detection of flicker and the detection of pattern were measured for nasal and temporal retinae of each eye separately. While confirming that these two types of thresholds can differ, depending on spatial frequency, the results provide no support for hemiretinal or hemispheric asymmetries in the distribution of the putative pattern and movement channels.

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.

Effect of temporal constraints on hemispheric asymmetries during spatial frequency processing

2006 ◽  
Vol 62 (3) ◽  
pp. 214-220 ◽  
Author(s):  
Carole Peyrin ◽  
Martial Mermillod ◽  
Sylvie Chokron ◽  
Christian Marendaz
Keyword(s):  
Spatial Frequency ◽  
Temporal Constraints ◽  
Hemispheric Asymmetries ◽  
Frequency Processing

Re-Examination of Evidence Questions Christman's (1989) Report of Moderate Experimental Support for the Visual Spatial Frequency Hypothesis

1995 ◽  
Vol 80 (3) ◽  
pp. 955-962
Author(s):  
Robert Fudin
Keyword(s):  
Literature Review ◽  
Spatial Frequency ◽  
Significant Interaction ◽  
Hemispheric Asymmetries ◽  
Experimental Support ◽  
Visual Spatial ◽  
Perceptual Characteristics ◽  
Experimental Comparisons

The visual spatial frequency hypothesis contends that perceptual characteristics of stimulus arrays can affect the magnitude and direction of hemispheric asymmetries in laterality experiments. In a 1989 literature review, Christman reported that 45 of 79 experimental comparisons yielded significant interactions for side of hemispheric advantage x perceptual characteristic which supported the visual spatial frequency hypothesis, a level of support he characterized as moderate. Re-examination of those 45 outcomes shows that in 20 of them either a significant interaction for side of hemispheric advantage x perceptual characteristic was not found or, if it was, the particulars do not agree fully with predictions of the visual spatial frequency hypothesis as presented by Christman in the 1989 paper. These findings suggest that experimental support for the visual spatial frequency hypothesis is weak, not moderate as characterized by Christman.

BOLD fMRI Response of Early Visual Areas to Perceived Contrast in Human Amblyopia

2000 ◽  
Vol 84 (4) ◽  
pp. 1907-1913 ◽  
Author(s):  
Bradley G. Goodyear ◽  
David A. Nicolle ◽  
G. Keith Humphrey ◽  
Ravi S. Menon
Keyword(s):  
Spatial Frequency ◽  
Neuronal Response ◽  
Blood Oxygenation ◽  
Normal Vision ◽  
Staircase Method ◽  
Visual Areas ◽  
Oxygenation Level ◽  
Fmri Response ◽  
Visual Cortical ◽  
Contrast Thresholds

In this study, we used a temporal two-alternative forced choice psychophysical procedure to measure the observer's perception of a 22% physical contrast grating for each eye as a function of spatial frequency in four subjects with unilateral amblyopia and in six subjects with normal vision. Contrast thresholds were also measured using a standard staircase method. Additionally, blood-oxygenation-level–dependent (BOLD) functional magnetic resonance imaging (fMRI) was used to measure the neuronal response within early visual cortical areas to monocular presentations of the same 22% physical contrast gratings as a function of spatial frequency. For all six subjects with normal vision and for three subjects with amblyopia, the psychophysically measured perception of 22% contrast as a function of spatial frequency was the same for both eyes. Threshold contrast, however, was elevated for the amblyopic eye for all subjects, as expected. The magnitude of the fMRI response to 22% physical contrast within “activated” voxels was the same for each eye as a function of spatial frequency, regardless of the presence of amblyopia. However, there were always fewer “activated” fMRI voxels during amblyopic stimulation than during normal eye stimulation. These results are consistent with the hypotheses that contrast thresholds are elevated in amblyopia because fewer neurons are responsive during amblyopic stimulation, and that the average firing rate of the responsive neurons, which reflects the perception of contrast, is unaffected in amblyopia.

Detecting and Identifying Mirror-Symmetric Letters in the Periphery: A Test of the Equivalent-Size Hypothesis

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 53-53
Author(s):  
R Yssaad ◽  
L T Maloney ◽  
K Knoblauch
Keyword(s):  
Spatial Frequency ◽  
Power Function ◽  
Local Scale ◽  
Form Perception ◽  
Scaling Parameter ◽  
Scale Parameters ◽  
Detection And Identification ◽  
Single Function ◽  
Contrast Thresholds ◽  
Single Power

If the visual mechanisms underlying form perception scale similarly with eccentricity, then performance in regions of different eccentricity should be characterised by a single function of the form f( s/ e) where s is a spatial variable, like size or spatial frequency, and e is a parameter that represents the local scale at that eccentricity. This formulation implies that performance at a given size s0 and eccentricity should be identical to that at a size s1= s0 e1/ e0, at a different eccentricity, where e0 and e1 are the local scale parameters for the two eccentricities. We refer to this as the equivalent-size hypothesis. We tested the equivalent-size hypothesis by measuring contrast thresholds for detection and identification of four mirror symmetric letters (b, p, d, q) for a series of sizes at each of three eccentricities (2, 4, and 8 deg). Psychometric functions were obtained for each size and eccentricity with the use of a spatial, 4-alternative forced-choice, double-judgment technique. First, observers specified at which of four positions around the fovea the stimulus appeared. Then they responded with the letter name. At each eccentricity, contrast thresholds for detection and identification as a function of size were described well by a power function. A single power function scaled for eccentricity was able to account for either the detection or the identification behaviour, and a single scaling parameter for the two tasks would not suffice.

Contrast Sensitivity Function for Stereopsis

Perception ◽  
1978 ◽  
Vol 7 (4) ◽  
pp. 423-429 ◽  
Author(s):  
John P Frisby ◽  
John E W Mayhew
Keyword(s):  
Spatial Frequency ◽  
Contrast Sensitivity ◽  
Narrow Band ◽  
Sensitivity Function ◽  
Contrast Sensitivity Function ◽  
Band Noise ◽  
Random Dot Stereograms ◽  
Simple Detection ◽  
Global Stereopsis ◽  
Contrast Thresholds

Contrast thresholds for stereopsis from narrow-band-filtered random-dot stereograms were compared with contrast thresholds for simple detection of similar narrow-band noise. Centre frequencies of filters were in the range 2·5–15 cycles deg−1. It was found that the contrast sensitivity function for stereopsis is similar in shape to that for detection, suggesting that as far as contrast requirements are concerned the mechanisms of global stereopsis do not show a bias in sensitivity to any particular spatial frequency but instead require a constant level of suprathreshold contrast regardless of spatial frequency.

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