@misc{WernerCiceroneKliegletal.1984,
  author    = {Werner, John S. and Cicerone, Carola M. and Kliegl, Reinhold and DellaRosa, Denise},
  title     = {Spectral efficiency of blackness induction},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-16897},
  year      = {1984},
  abstract  = {The spectral efficiency of blackness induction was measured in three normal trichromatic observers and in one deuteranomalous observer. The psychophysical task was to adjust the radiance of a monochromatic 60-120′ annulus until a 45′ central broadband field just turned black and its contour became indiscriminable from a dark surrounding gap that separated it from the annulus. The reciprocal of the radiance required to induce blackness with annulus wavelengths between 420 and 680 nm was used to define a spectral-efficiency function for the blackness component of the achromatic process. For each observer, the shape of this blackness-sensitivity function agreed with the spectral-efficiency function based on heterochromatic flicker photometry when measured with the same 60-120′ annulus. Both of these functions matched the Commission Internationale de l'Eclairage Vλ function except at short wavelengths. Ancillary measurements showed that the latter difference in sensitivity can be ascribed to nonuniformities of preretinal absorption, since the annular field excluded the central 60′ of the fovea. Thus our evidence indicates that, at least to a good first approximation, induced blackness is inversely related to the spectral-luminosity function. These findings are consistent with a model that separates the achromatic and the chromatic pathways.},
  language  = {en}
}
@misc{KlieglVolbrechtWerner1984,
  author    = {Kliegl, Reinhold and Volbrecht, Vicki J. and Werner, John S.},
  title     = {Influences of variation in lenticular and macular pigmentation on dichromatic neutral points},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-41101},
  year      = {1984},
  abstract  = {Protanopie, deuteranopic and tritanopic neutral points were computed by determining the wavelength of light that produced the same quantal-catch ratio in the photopigments as that produced by a broad-band light of specified color temperature (range: 2 800—6 600 K). The Vos-Walraven primaries were used as photopigment absorption spectra that were screened by varying densities of ocular (0.5—2.5 at 400 nm) and macular (0.0—1.0 at 460 nm) pigmentation. The computations were carried out in 1 nm steps for the wavelength range of 380 to 720 nm. Most of the empirically determined mean, neutral-point loci in the literature were predicted from these computations to within 1—2nm when average ocular and macular pigment densities were used. The neutral-point range associated with the extreme values of the prereceptoral screening pigments was up to 25 nm for protanopes and deuteranopes and up to 13 nm for tritanopes.},
  language  = {en}
}
@misc{WernerDonnellyKliegl1987,
  author    = {Werner, John S. and Donnelly, Seaneen K. and Kliegl, Reinhold},
  title     = {Aging and human macular pigment density : appended with translations from the work of Max Schultze and Ewald Hering},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-16836},
  year      = {1987},
  abstract  = {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°, 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 broad-band, short-wave background. Macular pigment density was determined by comparing sensitivity under these conditions for the fovea, where macular pigment is maximal, and 5° temporally. This difference spectrum, measured for 12 observers, matched Wyszecki and Stiles's standard density spectrum for macular pigment. To study variation in macular pigment density for a larger group of observers, measurements were made at only selected spectral points (460, 500 and 550 nm). The mean optical density at 460 nm for the complete sample of 50 subjects was 0.39. Substantial individual differences in density were found (ca. 0.10-0.80), but this variation was not systematically related to age.},
  language  = {en}
}