Use of Pulsed Magnetic Fields to Measure the Faraday Effect in Gases

Color recognition and discrimination under full-moon light

The ability to recognize and discriminate colors under full-moon light was measured Color naming was performed at three sizes (0.5°, 2°, and 4°) by the use of one white and six colored chips that spanned the spectrum at two levels of saturation. The results show that correct color recognition is possible under full-moon light. However, the recognition rate depends on a complex interaction between hue, level of saturation, and size of test field. For small fields and desaturated colors, the recognition rate is low. However, for saturated colors, most hues can be recognized at better than chance levels, with red being recognized very accurately.

Achromatic and chromatic sensation as a function of color temperature and retinal illuminance

Changes in color appearance with retinal illuminance were studied by scaling the achromatic, yellow, and blue sensation components for test lights with color temperatures from 3041 to 8650 K at 4.10, 2.18, and 0.33 log Td. At 4.10 log Td two observers showed similar pure whites (4823 and 5258 K) and narrow transition zones (1502 and 969 K) from yellow to blue chromatic response categories. The relative amounts of yellow, blue, and white varied with color temperature in a similar manner for both observers. One observer maintained similar absolute whites and transition zones for all illuminances. For the second observer the transition zone broadened and shifted to higher color temperatures as illuminance decreased. At color temperatures both above and below the transition zone chromatic saturation was greatest at the intermediate illuminance. The loss of saturation at 0.33 and 4.10 log Td is consistent with the observation that as the illuminance of a spectral color is raised above threshold, saturation increases to a maximum and then falls. Our findings reinforce the notion that at relatively low illuminances chromatic responses increase with increasing illuminance more rapidly than achromatic responses and that the opposite is true at high illuminances.