Systematic violations of von Kries rule reveal its limitations for explaining color and lightness constancy.

Cone contrast remains constant, when the same object/background is seen under different illuminations-the von Kries rule [Shevell, Vis. Res. 18, 1649 (1978)]. Here we explore this idea using asymmetric color matching. We find that von Kries adaptation holds, regardless of whether chromatic constancy index is low or high. When illumination changes the stimulus luminance (reflectance), lightness constancy is weak and matching is dictated by object/background luminance contrast. When this contrast is masked or disrupted, lightness constancy mechanisms are more prominent. Thus von Kries adaptation is incompatible with lightness constancy, suggesting that cortical mechanisms must underlie color constancy, as expected from neurophysiological studies [Zeki, Nature 284, 412 (1980); Wild, Nature 313, 133 (1985)].