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.
F. A. MOTE and ELEANOR C. REED, "The Effect of High Intensity and Short Duration versus Low Intensity and Long Duration of Intermittent Pre-Exposure upon Human Dark Adaptation," J. Opt. Soc. Am. 42, 521-524 (1952)