To determine, whether visual, fatigue, which can occur for some individuals working in red light at close distances, is a problem of importance for the operation of visual sonar displays. FINDINGS There was evidence that older, far-sighted individuals did show changes indicative of fatigue under red light while younger individuals with normal vision did not. No performance decrements were found for any group.

The second study investigated in more detail the lighting conditions, target sizes, and contrasts for which yellow is effective. Specifically these were low contrast targets in the middle of the range of spatial frequencies. The use of a white or a lighted surround theoretically should enhance the yellow advantage and it was shown to do so, adding a further explanation for the popularity of yellow goggles in snow-covered terrain. * This test was designed and constructed by Dr. Mark Vernoy of Palomar College, CA. We are indebted to him for making it available.

Since light is defined quantitatively as radiant energy evaluated according to the CIE photopic luminosity curve, ordinary t units are inappropriate whenever the organism's spectral sensitivity differs markedly from the CIE curve. Examples of differing spectral sensitivities include those of animals, of color defective individuals, and curves for all individuals under low light levels or with large fields. Calculations are presented of the amount of error involved when units of light are used for these inappropriate conditions; alternative solutions to the problem are discussed.

No abstract

No abstract