Abstract
Curves are presented showing the times required for three observers to resolve a series of high contrast targets after initial adaptation to red or white light of 3.4 ft-L when the target luminances were 3.22, 3.82, 4.17, 4.77, and 5.13 log μμL. The resolution times were also measured as a function of three levels of red and white initial adaptation, 22, 3.4, and 0.19 ft-L, while the target luminance was held constant at 4.17 log μμL. In addition, a few measurements were made on low contrast targets at this last luminance. The curves generally conform with previous determinations, rising steeply at first and reaching an asymptote within ten minutes. They are sharply divided into two distinct groups, depending on the color of the initial adapting light, red interfering less with the subsequent rise in acuity than white. The results indicate that the savings in time effected by the use of red rather than an equated white initial adapting light are not a function of the target illumination but remain approximately constant throughout the range of pure scotopic brightness at about 3 min. This decreased to about 2 min when the target luminance entered the mesopic range. Previous findings concerning the relation between target contrast and acuity, and that time savings with the use of red increase as the preadapting luminance increases, were confirmed.
© 1960 Optical Society of America
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