scholarly journals Curveball: A tool for rapid measurement of contrast sensitivity based on smooth eye movements

2018 ◽  
Vol 18 (12) ◽  
pp. 7 ◽  
Author(s):  
Scott W. J. Mooney ◽  
N. Jeremy Hill ◽  
Melis S. Tuzun ◽  
Nazia M. Alam ◽  
Jason B. Carmel ◽  
...  
Keyword(s):  
Eye Movements ◽  
Contrast Sensitivity ◽  
Rapid Measurement

scholarly journals Estimation of Contrast Sensitivity From Fixational Eye Movements

2018 ◽  
Vol 59 (13) ◽  
pp. 5408
Author(s):  
Jonathan Denniss ◽  
Chris Scholes ◽  
Paul V. McGraw ◽  
Se-Ho Nam ◽  
Neil W. Roach
Keyword(s):  
Eye Movements ◽  
Contrast Sensitivity ◽  
Fixational Eye Movements

scholarly journals Contrast sensitivity, V1 neural activity, and natural vision

2017 ◽  
Vol 117 (2) ◽  
pp. 492-508 ◽  
Author(s):  
James E. Niemeyer ◽  
Michael A. Paradiso
Keyword(s):  
Eye Movements ◽  
Contrast Sensitivity ◽  
Visual Processing ◽  
Brain Area ◽  
Saccadic Eye Movements ◽  
Visual Sensitivity ◽  
Natural Image ◽  
Spatial Frequencies ◽  
Natural Vision ◽  
Common Laboratory

Contrast sensitivity is fundamental to natural visual processing and an important tool for characterizing both visual function and clinical disorders. We simultaneously measured contrast sensitivity and neural contrast response functions and compared measurements in common laboratory conditions with naturalistic conditions. In typical experiments, a subject holds fixation and a stimulus is flashed on, whereas in natural vision, saccades bring stimuli into view. Motivated by our previous V1 findings, we tested the hypothesis that perceptual contrast sensitivity is lower in natural vision and that this effect is associated with corresponding changes in V1 activity. We found that contrast sensitivity and V1 activity are correlated and that the relationship is similar in laboratory and naturalistic paradigms. However, in the more natural situation, contrast sensitivity is reduced up to 25% compared with that in a standard fixation paradigm, particularly at lower spatial frequencies, and this effect correlates with significant reductions in V1 responses. Our data suggest that these reductions in natural vision result from fast adaptation on one fixation that lowers the response on a subsequent fixation. This is the first demonstration of rapid, natural-image adaptation that carries across saccades, a process that appears to constantly influence visual sensitivity in natural vision. NEW & NOTEWORTHY Visual sensitivity and activity in brain area V1 were studied in a paradigm that included saccadic eye movements and natural visual input. V1 responses and contrast sensitivity were significantly reduced compared with results in common laboratory paradigms. The parallel neural and perceptual effects of eye movements and stimulus complexity appear to be due to a form of rapid adaptation that carries across saccades.

scholarly journals Foveal vision at the time of microsaccades

2021 ◽  
Author(s):  
Naghmeh Mostofi ◽  
Janis Intoy ◽  
Michele Rucci
Keyword(s):  
Eye Movements ◽  
Contrast Sensitivity ◽  
Time Course ◽  
Visual Sensitivity ◽  
Saccadic Suppression ◽  
Visual Exploration ◽  
Social Grooming ◽  
Foveal Vision ◽  
High Acuity ◽  
Display Control

AbstractHumans use rapid eye movements (saccades) to inspect stimuli with the foveola, the region of the retina where receptors are most densely packed. It is well established that visual sensitivity is generally attenuated during these movements, a phenomenon known as saccadic suppression. This effect is commonly studied with large, often peripheral, stimuli presented during instructed saccades. However, little is known about how saccades modulate the foveola and how the resulting dynamics unfold during natural visual exploration. Here we measured the foveal dynamics of saccadic suppression in a naturalistic high-acuity task, a task designed after primate’s social grooming, which—like most explorations of fine patterns—primarily elicits minute saccades (microsaccades). Leveraging on recent advances in gaze-contingent display control, we were able to systematically map the peri-saccadic time-course of sensitivity across the foveola. We show that contrast sensitivity is not uniform across this region and that both the extent and dynamics of saccadic suppression vary within the foveola. Suppression is stronger and faster in the most central portion, where sensitivity is generally higher and selectively rebounds at the onset of a new fixation. These results shed new light on the modulations experienced by foveal vision during the saccade-fixation cycle and explain some of the benefits of microsaccades.

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 A computational observer model of spatial contrast sensitivity: Effects of photocurrent encoding, fixational eye movements and inference engine

2019 ◽  
Author(s):  
Nicolas P. Cottaris ◽  
Brian A. Wandell ◽  
Fred Rieke ◽  
David H. Brainard
Keyword(s):  
Eye Movements ◽  
Contrast Sensitivity ◽  
Cortical Neurons ◽  
Neural Population ◽  
Linear Filter ◽  
Response Dynamics ◽  
Translation Invariant ◽  
Fixational Eye Movements ◽  
Spatial Contrast Sensitivity ◽  
Observer Model

AbstractWe have recently shown that using the information carried by the mosaic of cone excitations of a stationary retina, the relative spatial contrast sensitivity function (CSF) of a computational observer has the same shape as a typical human subject. Absolute human sensitivity, however, is lower than the computational observer by a factor of 5 to 10. Here we model how additional known features of early vision affect spatial contrast sensitivity: fixational eye movements and the conversion of cone photopigment excitations to cone photocurrent responses. For a computational observer that uses a linear classifier applied to the responses of a stimulus-matched linear filter, fixational eye movements substantially change the shape of the spatial CSF, primarily by reducing sensitivity at spatial frequencies above 10 c/deg. For a computational observer that uses a translation-invariant calculation, in which decisions are based on the squared response of a quadrature-pair of linear filters, the CSF shape is little changed by eye movements, but there is a two-fold reduction in sensitivity. The noise and response dynamics of conversion of cone excitations into photocurrent introduce an additional two-fold sensitivity decrease. Hence, the combined effects of fixational eye movements and phototransduction bring the absolute sensitivity of the translation-invariant computational observer CSF to within a factor of 1 to 2 of the human CSF. We note that the human CSF depends on processing of the initial representation by many thalamic and cortical neurons, which are individually quite noisy. Our computational modeling suggests that the net effect of this noise on contrast-detection performance, when considered at the neural population level and behavioral level, is quite small: the inference mechanisms that determine the CSF, presumably in cortex, make efficient use of the information available from the cone photocurrents of the fixating eye.

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