Results 201 to 210 of about 1,210,014 (249)

Contrast in night vision

Vision Research, 1973
Abstract Simultaneous contrast has been ascribed so far to spatial interactions in retinal receptive fields. The antagonistic surround of retinal receptive fields disappears after dark adaptation. The present work shows that simultaneous contrast for large fields and border contrast effects are preceived at low scotopic luminances. Moreover, both the
Adriana Fiorentini, Lamberto Maffei
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Contrast summation in dichoptic vision

Psychological Research, 1983
Two sinusoidal gratings equal in contrast and either equal or different in spatial frequency, orientation and spatial phase were presented dichoptically. At low contrast, the subjects perceived a fused image of the gratings, no matter how different the spatial frequencies or orientations on the gratings were.
SPINELLI D, CATTANEO, ANTONINO
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Contrast adaptation and contrast masking in human vision

Proceedings of the Royal Society of London. Series B: Biological Sciences, 1991
After a preliminary study of visual evoked potentials (VEPS) to a test grating seen in the presence of masks at different orientations, psychophysical data are presented showing the effects of adaptation and of masking on thresholds for detecting the same test grating.
Harriet D. Speed, John Ross
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Contrast masking in human vision

Journal of the Optical Society of America, 1980
Contrast masking was studied psychophysically. A two-alternative forced-choice procedure was used to measure contrast thresholds for 2.0 cpd sine-wave gratings in the presence of masking sine-wave gratings. Thresholds were measured for 11 masker contrasts spanning three log units, and seven masker frequencies ranging +/- one octave from the signal ...
John M. Foley, Gordon E. Legge
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Polarization Contrast Vision in Octopus [PDF]

Journal of Experimental Biology, 1996
ABSTRACT While the ability to analyze polarized light is widespread among animals, its contribution to form vision has not yet been documented. We tested the hypothesis that polarization vision can be used for object discrimination, by training octopuses to distinguish between targets on the basis of the presence or absence of a pattern ...
Nadav Shashar, Thomas W. Cronin
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Contrast discrimination in peripheral vision

Journal of the Optical Society of America A, 1987
Contrast discrimination provides a psychophysical method for studying contrast coding in vision. Our purpose was to compare properties of contrast discrimination in central and peripheral vision. We used forced-choice procedures to measure contrast-increment thresholds as a function of pedestal contrast.
Gordon E. Legge, Daniel Kersten
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Vision in dementia: Contrast effects

Neurological Research, 1996
Contrast sensitivity has been shown to be affected in Alzheimer's disease (Ad). We investigated low contrast acuity and contrast sensitivity using clinical test charts in this patient population. Additionally, we tested patients with vascular dementia (vd) and mixed dementia (md), (Alzheimer' with vascular dementia).
Mary Louise Kean, Vasudevan Lakshminarayanan, Malcolm B. Dick, John Lagrave, Rodman Shankle   +4 more
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Characteristic of Contrast Vision

1987
Six typical threshold contrast-sensitivity functions, frequently found in our ophthalmological practice, are analyzed, using the concept of spatial filtering in order to understand how we see the everyday world in the case of normal and abnormal vision.
Maria L. F. De Mattiello, Ernesto Mazzeo, A. Gonella   +2 more
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Contrasting the Vision and the Reality

Journal of Religion & Abuse, 2001
Abstract This article advocates the use of developing individual core ethical values as the first step in a process of using one's own principles as a means of keeping focused and grounded. The article does not stop but encourages the reader to actually use the value through the introduction of a straightforward yet sophisticated decision model ...
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Contrast Sensitivity and Functional Vision

International Ophthalmology Clinics, 2003
How well does a person see faces in a crowd, read a newspaper, or drive an automobile at night? These are vital questions about a person's quality of life and safety. Obtaining answers to these questions requires tests of functional vision.
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