Iconic storage: the role of rods.

The hypothesis that rods mediate iconic storage was tested by presenting letters of one color against a field of another. The colors were chosen to be discriminable only by the cones, only by the rods, or both. Under dark adaptation, the rods had little if any effect on partial-report advantage; however, they were important in determining the phenomenal persistence of the stimulus. Under light adaptation, the rods played no apparent role in either type of persistence.