As intensity increases, the apparent hue of stimuli of a constant spectral distribution shifts towards blue, if its dominant wavelength is below around 500 nm; or yellow, if its dominant wavelength is above 500 nm.
As intensity is decreased, apparent hue shifts towards red or green.
[2] The effect was noted in 1866 by physiologist Ernst Wilhelm von Brücke, and experimental investigations by physicist and meteorologist Wilhelm von Bezold were published in 1873.
[5][6] A similar hue shift, the Abney effect, occurs when a visual stimulus is mixed with white light.
[7] The shift in the hue is also accompanied by the changes in the perceived saturation.