Elisabeth T Davis

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A quantitative multiple-channels model can account for changes in perceived spatial frequency between foveally and peripherally viewed patterns; these frequency shifts are as large as 0.47 octave (38.5%). Factors that change as a function of eccentricity and that can alter the appearance of visual patterns include (1) scaling of receptive-field sizes, (2)(More)
A grating viewed in the periphery usually appears to be of higher frequency than the same grating viewed at the fovea, for frequencies below the Nyquist frequency of the periphery. Systematic shifts in perceived frequency between fovea and periphery were found under several experimental conditions: spatially localized or extended sine-wave patterns, test(More)
Of the estimated 1 million patients each year in the United States who undergo surgery for media opacities, perhaps 5-10% fail to improve because of pre-existing, undiagnosed retinal and/or optic nerve disease. In this paper, the standard presurgical evaluation (case history, visual acuity, refraction, pupillary response testing, biomicroscopy,(More)
Effects of stimulus context on magnitude estimations and on category ratings were examined for a range of stimulus intensities of a 1-kHz tone. The stimuli were distributed in equal-interval steps of energy so they formed a perceptual cluster of high-intensity tones with a perceptual outlier at the lowest intensity. According to the Invariance Principle,(More)
We studied shifts in perceived spatial frequency of foveally viewed stimuli as a function of contrast, using lower contrasts and/or a lower range of spatial frequencies than used previously by others. Reliable shifts in perceived spatial frequency were found, but the direction of the shift at low frequencies was not the same as at high frequencies for some(More)
The effects of aging, interocular comparisons, pupil dilation, iris pigmentation, and simulated cataracts on bright flash visual evoked potentials (VEP's) of normal observers were studied to assess the flash VEP as a potential predictor of postsurgical visual function in cataract patients. Seventy-six observers (from 20 to 80 years old) were tested for age(More)