Memory color effect
Memory color is the canonical hue of a type of object (e.g., sky, leaf, banana, or apple) that human observers acquire through their experiences with instances of that type. For example, most human observers know that an apple typically has a reddish hue; this knowledge about the canonical color which is represented in memory constitutes a memory color.[1][2]
The memory color effect is the phenomenon that memory colors directly modulate the appearance of the actual colors of objects. For example, normal human trichromats, when presented with a gray banana, often perceive the gray banana as being yellow - the banana's memory color. In light of this, subjects typically adjust the color of the banana towards the color blue - the opponent color of yellow - when asked to adjust its surface to gray to cancel the subtle activation of banana's memory color.[3] Subsequent empirical studies have also shown the memory color effect on man-made objects (e.g. smurfs, German mailboxes), the effect being especially pronounced for blue and yellow objects. To explain this, researchers have argued that because natural daylight shifts from short wavelengths of light (i.e., bluish hues) towards light of longer wavelengths (i.e., yellowish-orange hues) during the day, the memory colors for blue and yellow objects are recruited by the visual system to a higher degree to compensate for this fluctuation in illumination, thereby providing a stronger memory color effect.[4]
Significance to the evolution of trichromacy
While objects that possess a canonical hue make up a small percentage of the objects which populate humans’ visual experience, the human visual system evolved in an environment populated with objects that possess a canonical hue. This suggests that the memory color effect is related to the emergence of trichromacy because it has been argued that trichromacy evolved to optimize the ability to detect ripe fruits - objects that appear in canonical hues.[5]
In perception research
In perception research, the memory color effect is cited as evidence for the opponent color theory. Researchers have also found empirical evidence that suggests memory color is recruited by the visual system to achieve color constancy.[6]
References
- ^ Ewald Hering (1964). Outlines of a theory of the light sense. Harvard University Press.
- ^ Bartleson, C. J. (1960). "Memory Colors of Familiar Objects". Journal of the Optical Society of America. 50 (1): 73. doi:10.1364/JOSA.50.000073. ISSN 0030-3941.
- ^ Hansen, T.; Olkkonen, M.; Walter, S.; Gegenfurtner, K.R. (October 2006). "Memory modulates color appearance". Nature Neuroscience. 9 (11): 1367–1368. doi:10.1038/nn1794. PMID 17041591.
- ^ Witzel, C.; Valkova, H.; Hansen, T.; Gegenfurtner, K.R. (March 2011). "Object knowledge modulates colour appearance". I-perception. 2 (1): 13–49. doi:10.1068/i0396. PMC 3485772. PMID 23145224.
- ^ Regan, B.C.; Julliot, C.; Simmen, B.; Vienot, F.; Charles-Dominique, P.; Mollon, J.D. (March 2011). "Fruits, foliage and the evolution of primate colour vision". Philosophical Transactions of the Royal Society B: Biological Sciences. 356 (1407): 229–283. doi:10.1098/rstb.2000.0773. PMC 1088428. PMID 11316480.
- ^ Granzier, J.M.; Gegenfurtner, K.R. (2012). "Effects of memory colour on colour constancy for unknown coloured objects". I-Perception. 3 (3): 190–215. doi:10.1068/i0461. PMC 3485846. PMID 23145282.