Color constancy improves as the amount of valid cues to the illuminant is increased (Jin & Shevell,
1996; Kraft & Brainard,
1999; Kraft, Maloney, & Brainard,
2002; Yang & Maloney,
2001). However, color constancy is incomplete even in realistic experimental settings, which poses the question of whether there might be additional mechanisms at play that cannot be revealed with simplified stimulus arrangements. von Helmholtz (
1867) was one of the first to emphasize the role of previous experience together with sensory input in the formation of a perceptual image (
Anschauungsbild). Along the same lines, Hering (
1920) suggested that the knowledge of an object's typical color might be a clue in estimating an unknown illuminant. Studies on memory colors indicate that the knowledge of an object's typical color can indeed affect an object's perceived color (Adams,
1924; Bruner, Postman, & Rodrigues,
1951; Delk & Fillenbaum,
1965; Duncker,
1939; Hansen & Gegenfurtner,
2006; Hansen, Olkkonen, Walter, & Gegenfurtner,
2006; Hurlbert & Ling,
2005; but see Bolles, Hulicka, & Hanly,
1959). Duncker (
1939) showed that when subjects were presented with a donkey and a leaf cut from the same material, the leaf was matched to a significantly greener color in a color wheel than the donkey. However, the effect only showed reliably in 55–75% of the subjects. Later reports on the memory color effect are somewhat contradictory, some showing a strong effect in various settings (Delk & Fillenbaum,
1965), others finding the effect only in settings where stimulus information was much reduced or the matching task otherwise made difficult (Bolles et al.,
1959; Bruner et al.,
1951). Observers could not adjust the stimulus color themselves in any of these studies. Moreover, in most cases, the matching was done over a spatial or a temporal interval, which necessarily required keeping the color in memory during matching (Adams,
1924; Bolles et al.,
1959; Bruner et al.,
1951; Duncker,
1939; Hurlbert & Ling,
2005). Even in cases where simultaneous matching was possible, subjects had to give a verbal response (Bruner et al.,
1951; Delk & Fillenbaum,
1965). These limitations might have led to measuring other than purely perceptual effects—for instance, an observer might have asked the experimenter to set the color wheel to a greener hue in the case of the leaf merely because leaves tend to be greener than donkeys.