Measurements of the contrast threshold for peripheral vision for size d of the circular test spot between 4′ and 420′ and for flash time t between 0.02 and 1 sec are presented. Wavelengths for adapting field λ1 and test stimulus λ2 6500 and 5250A so that four λ1 − λ2 combinations were explored. The merits of theoretical speculations on the perception of contrast considering the statistical fluctuations in the number of incident quanta and nerve impulses are discussed.
It proved that the perception of red light is dominant over the stimulation of the rod system by the background and that the state of adaptation of the one eye and the perception of light via this eye is not affected or influenced by the actual stimulation or state of adaptation of the opposite eye when influences due to variations in pupil size are eliminated. Exception must be made for very high brightnesses of a green background.
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