Fig. 16 Each cone photopigment has some sensitivity to light across the spectrum, although each differs from the other. Perhaps surprisingly, the blue cones (S cones) are no more sensitive to blue light than the red or green cones (upper left) .All three cones are involved in the detection of blue lights in a normal everyday environment. However, gazing at a bright yellow light (i.e., white light with blue/violet removed) desensitizes the red (L) and green (G) cones and leaves the blue (S) cones more sensitive to deep blue or violet light (lower left) when it is flashed on top of the yellow background (upper left).