Spatial vision in strabismic cats

1983 ◽  
Vol 50 (1) ◽  
pp. 287-296 ◽  
Author(s):  
K. Holopigian ◽  
R. Blake
Keyword(s):  
Contrast Sensitivity ◽  
Preceding Paper ◽  
Spatial Vision ◽  
Performance Difference ◽  
Single Class ◽  
Convergent Strabismus ◽  
Contrast Thresholds

Contrast thresholds for detection of stationary and flickering gratings were measured behaviorally for each eye of cats raised with induced convergent strabismus. The performance of the deviating eye was inferior to that of the nondeviating eye when test patterns were stationary. Flicker served to reduce the performance difference between the eyes in two cats but not in a third. These results suggest that strabismus amblyopia may not result from deficits within a single class of neurons. In all strabismic cats the contrast sensitivity of the nondeviating eye was significantly reduced relative to normal cats. These behavioral findings, including the deficits found bilaterally, correspond very well with results from cortical recordings from these and other strabismic cats presented in the preceding paper (7).

Visual Contrast Sensitivity Functions Obtained with Colored and Achromatic Gratings

1979 ◽  
Vol 21 (2) ◽  
pp. 225-228 ◽  
Author(s):  
Michael A. Nelson ◽  
Ronald L. Halberg
Keyword(s):  
Contrast Sensitivity ◽  
Spatial Information ◽  
Sensitivity Functions ◽  
Visual Contrast ◽  
Spatial Frequencies ◽  
Sinusoidal Gratings ◽  
Visual Contrast Sensitivity ◽  
Contrast Thresholds

Threshold contrasts for red, green, and achromatic sinusoidal gratings were measured. Spatial frequencies ranged from 0.25 to 15 cycles/deg. No significant differences in contrast thresholds were found among the three grating types. From this finding it was concluded that, under conditions of normal viewing, no significant differences should be expected in the acquisition of spatial information from monochromatic or achromatic displays of equal resolution.

Bandwidth of the Contrast Sensitivity Function as an Index of Spatial Vision with Application to Refraction

1990 ◽  
Vol 67 (4) ◽  
pp. 260-267 ◽  
Author(s):  
BAI-CHUAN JIANG ◽  
CHARLES T. SCIALFA ◽  
RICHARD A. TYRRELL ◽  
PHILIP M. GARVEY ◽  
HERSCHEL W. LEIBOWITZ
Keyword(s):  
Contrast Sensitivity ◽  
Spatial Vision ◽  
Sensitivity Function ◽  
Contrast Sensitivity Function

An Assessment of Decision-Making as a Possible Factor in the Age-Related Loss of Contrast Sensitivity

Perception ◽  
1986 ◽  
Vol 15 (5) ◽  
pp. 541-552 ◽  
Author(s):  
James D Morrison ◽  
James Reilly
Keyword(s):  
Decision Making ◽  
Contrast Sensitivity ◽  
Contrast Threshold ◽  
Sinusoidal Grating ◽  
Hit Rate ◽  
Grating Pattern ◽  
Age Related ◽  
Spatial Frequencies ◽  
Young Subjects ◽  
Contrast Thresholds

The possibility that changes in decision-making may contribute to the age-related decline in contrast sensitivity has been investigated in nineteen young subjects (ages 21–38 years) and twenty-seven old subjects (ages 55–92 years). A signal detection paradigm was employed in which the detection of stationary sinusoidal grating patterns was measured at 3 and 15 cycles deg−1 for a range of contrasts which were psychophysically equivalent for each subject. A decline in contrast sensitivity with age at the spatial frequencies studied was confirmed for contrast thresholds obtained both by the ascending method and from the 50% hit rate for detection of the grating pattern. The criterion adopted for decision-making, expressed as both β and percentage bias, did not change significantly between young and old subjects at 15 cycles deg−1. At 3 cycles deg−1, criterion β did not change significantly at x0.8, x1.0, or x1.2 contrast threshold, but at contrast giving 50% hit rate there was a significant increase with age. The percentage bias increased significantly at contrast threshold but not at 50% hit rate. It is inferred from the results that the loss of contrast sensitivity was not accountable in terms of the adoption of a more conservative criterion by older subjects. Hence visual loss in ageing is attributed to changes within the visual pathway rather than within higher decision-making centres.

scholarly journals Gradiate: a radial sweep approach to measuring detailed contrast sensitivity functions from eye movements

2020 ◽  
Author(s):  
Scott William Joseph Mooney ◽  
Nazia Alam ◽  
N. Jeremy Hill ◽  
Glen T. Prusky
Keyword(s):  
Eye Movements ◽  
Aspect Ratio ◽  
Contrast Sensitivity ◽  
Spatial Vision ◽  
Shape Factors ◽  
High Agreement ◽  
Low Contrast ◽  
Sensitivity Functions ◽  
Logmar Acuity ◽  
Visual Health

The contrast sensitivity function (CSF) is an informative measure of visual health, but the practical difficulty of measuring it has impeded detailed analyses of its relationship to different visual disorders. Furthermore, most existing tasks cannot be used in populations with cognitive impairment. We analyzed detailed CSFs measured with a non-verbal procedure called “Gradiate”, which efficiently infers visibility from eye movements and manipulates stimulus appearance in real time. Sixty observers of varying age (38 with refractive error) were presented with moving stimuli. Stimulus spatial frequency and contrast advanced along fifteen radial sweeps through CSF space in response to stimulus-congruent eye movements. A point on the CSF was recorded when tracking ceased. Gradiate CSFs were reliable and in high agreement with independent low contrast acuity thresholds. Overall CSF variation was largely captured by two orthogonal factors (“radius” and “slope”), or two orthogonal shape factors when size was normalized (“aspect ratio” and “curvature”). CSF radius was highly predictive of LogMAR acuity, as were aspect ratio and curvature together, but only radius was predictive of observer age. Our findings suggest that Gradiate holds promise for assessing spatial vision in both verbal and non-verbal populations and indicate that variation between detailed CSFs can reveal useful information about visual health.

scholarly journals More than noise: Context-dependant luminance contrast discrimination in a coral reef fish (Rhinecanthus aculeatus)

2020 ◽  
Author(s):  
Cedric P. van den Berg ◽  
Michelle Hollenkamp ◽  
Laurie J. Mitchell ◽  
Erin J. Watson ◽  
Naomi F. Green ◽  
...  
Keyword(s):  
Contrast Sensitivity ◽  
Luminance Contrast ◽  
Individual Species ◽  
Diverse Range ◽  
Bright Spots ◽  
Context Dependent ◽  
Luminance Discrimination ◽  
Contrast Perception ◽  
Contrast Discrimination ◽  
Contrast Thresholds

AbstractAchromatic (luminance) vision is used by animals to perceive motion, pattern, space and texture. Luminance contrast sensitivity thresholds are often poorly characterised for individual species and are applied across a diverse range of perceptual contexts using over-simplified assumptions of an animal’s visual system. Such thresholds are often estimated using the Receptor Noise Limited model (RNL) using quantum catch values and estimated noise levels of photoreceptors. However, the suitability of the RNL model to describe luminance contrast perception remains poorly tested.Here, we investigated context-dependent luminance discrimination using triggerfish (Rhinecanthus aculeatus) presented with large achromatic stimuli (spots) against uniform achromatic backgrounds of varying absolute and relative contrasts. ‘Dark’ and ‘bright’ spots were presented against relatively dark and bright backgrounds. We found significant differences in luminance discrimination thresholds across treatments. When measured using Michelson contrast, thresholds for bright spots on a bright background were significantly higher than for other scenarios, and the lowest threshold was found when dark spots were presented on dark backgrounds. Thresholds expressed in Weber contrast revealed increased contrast sensitivity for stimuli darker than their backgrounds, which is consistent with the literature. The RNL model was unable to estimate threshold scaling across scenarios as predicted by the Weber-Fechner law, highlighting limitations in the current use of the RNL model to quantify luminance contrast perception. Our study confirms that luminance contrast discrimination thresholds are context-dependent and should therefore be interpreted with caution.

The Binocular Summation of Chromatic Contrast

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 145-145 ◽  
Author(s):  
D R Simmons ◽  
F A A Kingdom
Keyword(s):  
Contrast Sensitivity ◽  
Detection Threshold ◽  
Luminance Contrast ◽  
Binocular Summation ◽  
Chromatic Contrast ◽  
Probability Summation ◽  
Investigative Ophthalmology ◽  
Contrast Thresholds ◽  
Detection Mechanisms ◽  
Neural Summation

The level of binocularity possessed by mechanisms sensitive to chromatic contrast is still unclear. Recent studies of stereopsis and chromatic contrast have suggested that stereopsis is maintained at isoluminance, although the contrast sensitivity and disparity ranges of chromatic stereopsis mechanisms are reduced compared to luminance stereopsis mechanisms. Rose, Blake, and Halpern (1988 Investigative Ophthalmology and Visual Science29 283 – 290) hypothesised a link between binocular summation (ie the superiority of binocular detection over monocular detection) and stereopsis. Is this link maintained with heterochromatic isoluminant stimuli? To address this question, the binocular and monocular contrast thresholds for the detection of 0.5 cycle deg−1 Gabor patches were measured. The stimuli possessed different relative amounts of colour and luminance contrast ranging from isoluminance (red/green) to isochrominance (yellow/black) through intermediate values. It was found that, with these stimuli, binocular detection was well modelled by assuming independent mechanisms sensitive to chromatic contrast and luminance contrast. Furthermore, with isoluminant stimuli, levels of binocular summation were above those expected from probability summation between the eyes, thus providing evidence for binocular neural summation within chromatic detection mechanisms. Given that stereoscopic depth identification is impossible at contrast detection threshold with isoluminant heterochromatic stimuli, these results suggest that the link between stereopsis and levels of binocular neural summation may not be a particularly strong one. These results also provide clear evidence for the binocularity of chromatic detection mechanisms.

scholarly journals Treated amblyopes remain deficient in spatial vision: A contrast sensitivity and external noise study

2007 ◽  
Vol 47 (1) ◽  
pp. 22-34 ◽  
Author(s):  
Changbing Huang ◽  
Liming Tao ◽  
Yifeng Zhou ◽  
Zhong-Lin Lu
Keyword(s):  
Contrast Sensitivity ◽  
Spatial Vision ◽  
External Noise

Spatial Vision and Aging. I: Contrast Sensitivity

1980 ◽  
Vol 35 (5) ◽  
pp. 692-699 ◽  
Author(s):  
R. Sekuler ◽  
L. P. Hutman
Keyword(s):  
Contrast Sensitivity ◽  
Spatial Vision

scholarly journals Sensitivity to visual motion in amblyopic macaque monkeys

2006 ◽  
Vol 23 (2) ◽  
pp. 247-256 ◽  
Author(s):  
LYNNE KIORPES ◽  
CHAO TANG ◽  
J. ANTHONY MOVSHON
Keyword(s):  
Contrast Sensitivity ◽  
Visual Motion ◽  
Spatial Scales ◽  
Spatial Vision ◽  
Motion Sensitivity ◽  
Sensitivity Functions ◽  
Wide Range ◽  
Spatial Contrast Sensitivity ◽  
Spatiotemporal Integration ◽  
Fellow Eyes

Amblyopia is usually considered to be a deficit in spatial vision. But there is evidence that amblyopes may also suffer specific deficits in motion sensitivity as opposed to losses that can be explained by the known deficits in spatial vision. We measured sensitivity to visual motion in random dot displays for strabismic and anisometropic amblyopic monkeys. We used a wide range of spatial and temporal offsets and compared the performance of the fellow and amblyopic eye for each monkey. The amblyopes were severely impaired at detecting motion at fine spatial and long temporal offsets, corresponding to fine spatial scale and slow speeds. This impairment was also evident for the untreated fellow eyes of strabismic but not anisometropic amblyopes. Motion sensitivity functions for amblyopic eyes were shifted toward large spatial scales for amblyopic compared to fellow eyes, to a degree that was correlated with the shift in scale of the spatial contrast sensitivity function. Amblyopic losses in motion sensitivity, however, were not correlated with losses in spatial contrast sensitivity. This, combined with the specific impairment for detecting long temporal offsets, reveals a deficit in spatiotemporal integration in amblyopia which cannot be explained by the lower spatial resolution of amblyopic vision.

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