[Autopsy case of plasma cell granulomas of meninges with difficulty of the diagnosis].
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Aged↗
Biomedical subjects
M Ayama
Publications and source records attributed to M Ayama.
Dependence of the chromatic valence function on chromatic standards.
The red, green, yellow, and blue curve portions of chromatic valence functions (CVFs) were measured by an iso-cancellation technique using three or four different chromatic standards (cancellation stimuli of fixed intensity and chromaticity) for each of the four curve portions. Curve shapes of the red, green, and yellow CVF portions varied with different chromatic standards, while that of blue did not. These results of chromatic standard dependency in CVFs are discussed with respect to opponent equilibria in a color mixture space.
Adult↗
Constant hue loci of unique and binary balanced hues at 10, 100, and 1000 Td.
Constant hue loci for unique red, yellow, green, and blue and the loci of four binary balanced hues (e.g., equally reddish and yellowish) were measured at 10, 100, and 1000 Td for two observers. Wavelengths of the unique hues were not invariant from 10 to 1000 Td. In Judd's modification of the 1931 CIE chromaticity diagram, only the unique yellow loci at 10 and 1000 Td plotted as straight lines. The other constant hue loci were curved, and all the constant hue loci changed with retinal illuminance.
Color Perception↗
Additivity of yellow chromatic valence.
The additivity of yellow chromatic valence was investigated by the hue cancellation method for two normal observers. Additivity held in 530-550 nm and 600-630 nm pairs, while additivity failure of reduction type occurred in 530-570 nm pair for both observers. Additivity failure of enhancement type occurred in 530-600 and 530-630 nm pairs in which one observer showed reduction type failure when mixture ratio of 530 nm is greater than 600 or 630 nm. The results suggest a nonlinear property of the yellow-blue process and are discussed in an interaction between the two opponent processes.
Color Perception↗
Small, brief foveal stimuli: an additivity experiment.
In an additivity experiment, increment thresholds were determined for 510 and 660 nm and for 470 and 570 nm. These thresholds were determined for each wavelength separately and for the wavelengths of each pair mixed. These measurements were made against a 1000-Td white background using fields subtending 0.16 degrees and 1.04 degrees visual angles and at 10- and 200-msec durations. For most conditions with the 510- and 660-nm pair, additivity of the reduction type was obtained. Generally, the larger field and longer duration produced larger additivity failures than the smaller field and shorter duration. For the 470- and 570-nm pair, two of the three observers showed additivity for the 0.16 degrees field in both the long- and the short-duration conditions. The larger field with longer durations yielded additivity failure for the three observers, but these failures were smaller than for the 510- and 660-nm pair.
Adult↗
Flicker photometry: residual minimum flicker.
We show that when all possible optical artifacts are eliminated in a flicker photometric procedure, there is still a residual minimum flicker after color fusion occurs. Our stimuli were alternated with approximately rectangular pulses; we obtained results contrary to those of a previous report in which the stimuli were alternated sinusoidally. In a subsidiary test using a computer-generated cosine wave on a RGB monitor, one observer perceived no residual flicker but a second observer did.
Adult↗
Additivity of red chromatic valence.
The additivity of red chromatic valence was investigated by the hue cancellation method for 4 normal observers. Additivity held for wavelength combinations of 610-680 nm and 400-440 nm. When using 400-680 nm, additivity failure of enhancement type was found for two observers, reduction type failure for a third, and additivity, for a forth. The results suggest a nonlinear property of the red-green process for some observers and are discussed in terms of the contribution of B-cones to the process.
Adaptation, Ocular↗
Just noticeable inhomogeneity criterion for determining wavelength discrimination functions.
The visual criterion of just noticeable inhomogeneity is described for determining wavelength discrimination functions. It involved determining the wavelength differences between reference and test fields required to produce a just noticeable inhomogeneity which cannot be eliminated by a brightness adjustment. The fields formed a checkerboard pattern the element size of which variable. Tritanopic delta lambda functions were obtained by using the small field insensitivity of the fovea. Just noticeable border, data obtained from bipartite field studies, were replicated with this checkerboard field.
Color Perception↗
Chromatic valence curves: alternative interpretation derived by the direct matching method.
The amount of red chromatic valence of the red-green opponent colors channel of the human visual system has been reported to be greatly reduced in short wavelengths when the hue-matching method is used to measure red valence instead of the more typical cancellation method. Receptive fields with a silent surround were postulated to explain the reduction, and it was emphasized that the reduced valence curve represented the true chromatic valence curve of the visual system. In the present studies the previous results are interpreted to be a direct consequence of the method and the particular matching stimuli used. It is shown that the reduction can be explained by the existing color-matching data without appealing to the silent surround hypothesis.
Color Perception↗
Additivity of opponent chromatic valence.
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Color Perception↗