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  • John Werner
  • Journal of the Optical Society of America
  • 1982
Scotopic spectral sensitivity was measured for nine observers (aged 4.5 months to 66 years) from 400 to 650 nm (10-nm steps) by using a 42 degree naturally viewed stimulus. The dependent measure was the visually evoked cortical-potential amplitude that was phase locked to an 8-Hz flickering stimulus. Sensitivity was similar for all observers at middle and(More)
The optical density of human macular pigment was measured for 50 observers ranging in age from 10 to 90 years. The psychophysical method required adjusting the radiance of a 1 degree, monochromatic light (400-550 nm) to minimize flicker (15 Hz) when presented in counterphase with a 460 nm standard. This test stimulus was presented superimposed on a(More)
OBJECTIVES To elucidate the visual significance of the foveal pit by measuring foveal architecture and function and to reassess use of the term foveal hypoplasia (as visual acuity can vary among patients who lack a pit). METHODS We describe 4 patients who lack a foveal pit. Visual acuities ranged from 20/20 to 20/50. Stratus and Cirrus (Carl Zeiss(More)
Contrast sensitivity functions (CSFs) of 25 infants were measured longitudinally at 4, 6 and 8 months of age using a preferential-looking method and the method of constant stimuli. Sine-wave gratings varied from 0.27 to 4.32 c/deg, contained eight unattenuated cycles (with edges tapered to uniform gray), and rose to the desired contrast in 2 sec. (1) The(More)
Mixtures of monochromatic lights that appear achromatic were measured for 50 normal, trichromatic observers ranging in age from 11 to 78 years. Stimuli were presented to one eye as a 1 degree-diameter, 1-s flash (10-s interstimulus interval) in Maxwellian view. We found the achromatic locus by varying the intensity ratio of each observer's spectral unique(More)
Accurately processing orientation information is a fundamental component of visual performance. Single-unit recordings have shown that the orientation tuning of individual neurons in macaque cortical areas V1 and V2 is reduced dramatically with age (M. T. Schmolesky, Y. Wang, M. Pu, & A. G. Leventhal, 2000; S. Yu, Y. Wang, X. Li, Y. Zhou, & A. G. Leventhal,(More)
Classical receptive-field concepts have been used to explain local perceptual effects such as border contrast and Mach bands, but are not sufficient to explain global perceptual effects. Examples are the perception of illusory contours, area contrast, color constancy, depth planes, coherent motion and texture contrast. These diverse effects require(More)
Opponent chromatic response functions were determined from monochromatic, equal-luminance stimuli from 400 to 700 nm for three observers using a hue cancellation procedure. The same observers scaled the hue of the stimuli using the terms red, green, yellow, and blue. The results showed that the hue scaling was accurately predicted from the cancellation(More)
Contrast sensitivity functions of forty 4-month-old human infants were measured using a preferential-looking method and the method of constant stimuli. Circular sinewave gratings varied from 0.27 to 1.08 c/deg, contained eight unattenuated cycles (with edges tapered to uniform gray), and rose to the desired contrast in 2 sec. Log contrast sensitivities for(More)
Spectral efficiency functions based on heterochromatic flicker photometry (HFP) were measured for three adults and 42 infants using a rapid visually-evoked potential (VEP) method. A 5 degrees-diameter, broadband standard (0.6 cd/m2) was presented in square-wave counterphase (15 Hz) with one of 13 monochromatic lights (420-660 nm; 20 nm steps). The intensity(More)