The responses to red stimuli presenting different distributions of time luminance are compared. The height of the x wave seems to be independent of time distribution of the light stimulus while the height of the b wave is greater, the greater the time of variation of the luminance. The latencies to peak of both waves are greater with a slowly rising stimulus than with a steep stimulus.
LUCIA RONCHI, "On the Electrical Response of the Human Eye to Red Stimuli of Different Time Distribution of Luminance," J. Opt. Soc. Am. 48, 437-438 (1958)