p297fig08.08 When a second flash is more intense than the first flash, then apparent motion may occur from the second to the first flash.<BR>||  Delta motion: motions from the second to the first flash.  Data: (Kolers 1972; Korte 1915). Simulation: (Grossberg, Rudd 1992).  This occurs when the luminance or contrast of the second flash is large compared to that of the first flash. Sustained and transient cells obey shunting dynamics whose averaging rates speed up with output intensity.  The first flash to wane is the one that will be the source of the G-wave.