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Biomedical subjects

J J Wisowaty

Publications and source records attributed to J J Wisowaty.

5 recordsLinked to original sources
PubMed1984

Selective color effects in dichoptic masking.

Dichoptic masking was investigated under conditions designed to isolate, in turn, achromatic and chromatic pathways in the visual system. Red, green, and blue tests and masks were used in various combinations. For the achromatic condition, achieved with a 3 min, 10 msec test flash and a 3 deg masking flash and with both eyes light adapted, there is essentially no dichoptic masking. With a 50 min test flash and conditions otherwise the same, a small amount of chromatically nonselective dichoptic masking occurs which is attributed to interaction between fairly remote contours, a form of weak pattern masking. For the chromatic condition, achieved with a 1 deg test flash delivered for 200 msec with both eyes light adapted, a small, nonselective masking effect, also attributed to weak pattern masking, occurs for most color combinations. The only chromatically-selective effect observed occurs for blue tests seen with blue masks. For this condition, dichoptic thresholds reach a maximum at modest photopic luminances of the mask and then decline.

Adaptation, Ocular↗
PubMed1983

An action spectrum for the production of transient tritanopia.

The site of yellow/blue chromatic-opponency has been thought to include synergistic input from either or both of the longwave-sensitive cone types to the "yellow" side. It has remained controversial whether one of these cone types provides all the "yellow" input or if both contribute to some extent. By measuring the action spectrum of adapting fields that produce transient tritanopia at their offset it appears that both the red- and green-sensitive cone types contribute in approximately the same ratio that they contribute to luminance. There also appears to be a contribution from an antagonistic red/green mechanism in producing transient tritanopia. These seem consistent with current physiological and psychophysical evidence.

Adaptation, Ocular↗
PubMed1981

Estimates for the temporal response characteristics of chromatic pathways.

When equiluminous red and green fields are temporally alternated, it is generally accepted that the hue of the field fuses to yellow at a slower flicker rate than the critical flicker frequency (cff). However, when sufficient precautions are taken to avoid optically created achromatic artifacts and the illumination of the test field is kept fairly low (70 trolands), the modulation threshold for color fusion and that for flicker fusion are equivalent. The purely chromatic, artifact-free stimulus shows a much lower cff than has been reported in the literature under comparable conditions. It seems likely that many studies of the chromatic pathways have overestimated the ability of these pathways to follow rapid temporal alternation, presumably because the more sensitive achromatic pathways were detecting achromatic artifacts. A simple means for detecting achromatic artifacts in a temporal alternation will be demonstrated by the finding that an equiluminous surrounding field enhances modulation sensitivity only for achromatic flicker and not for chromatic flicker.

Color Perception↗
PubMed1980

Equations for chromatic discrimination models.

Equations are derived to fit the cone sensitivity values of Smith and Pokorny, which are based mainly upon Judd's modified color matching functions and the spectral sensitivities of normal and dichromatic observers. The equations, which fit Smith and Pokorny's values to within 1 to 3%, are smooth and differentiable. Derivatives of cone sensitivities for an equal luminance spectrum, which are of particular importance for models of chromatic discrimination, have been calculated and are shown graphically.

Color Perception↗