The influence of intermittent pre-exposure upon subsequent dark adaptation was investigated for two intermittent conditions. In one condition the intensity was increased in the same proportion as the amount of light-time in the light-dark ratio was decreased, keeping duration constant. In the other, intensity was constant but the duration was extended to compensate for variations in light-time. Both conditions were compared with equivalent control pre-exposures to continuous light. The control intensities and durations were 140, 281, and 562 mL and 1 and 3 minutes. The rate of intermittence was 1 cycle/second, and four light-to-dark ratios were used. The curves of dark adaptation obtained after intermittent pre-exposures of constant duration but different intensities were almost identical with those after the equivalent control pre-exposure. This was not so for the intermittent pre-exposures of constant intensity but different durations; after the longer durations, dark adaptation was much slower than after the equivalent control condition.
© 1952 Optical Society of AmericaFull Article | PDF Article