Abstract
Most people are trichromats, but some people have an extra kind of cone cell in their retinas: they are tetrachromats. Recent science shows that some tetrachromats make distinctions between reflectances that ordinary viewers are unable to detect. This paper asks what kind of colour experience these tetrachromats have. It rejects the claim that they simply see finer gradations of those colours familiar to trichromats. Instead, it draws on both scientific evidence and anecdotal data to argue that tetrachromats’ visual acuity is due to seeing novel colours: elementary colours that trichromat viewers are unable to see or imagine.
References
Abramov, I., & Gordon, J. (2005). Seeing unique hues. Journal of the Optical Society of America A, 22, 2143–2153.
Adcock, B. (2022, January 30). “I’m really just high on life and beauty”: The woman who can see 100 million colours. The Guardian. https://www.theguardian.com/society/2022/jan/30/im-really-just-high-on-life-and-beauty-the-woman-who-can-see-100-million-colours
Albers, J. (1975). Interaction of color: Unabridged text and selected plates (Rev. ed). Yale University Press.
Allen, K. (2016). A naı̈ve realist theory of colour. Oxford University Press.
Blog, M. C. (2015). Beyond average color vision: An interview with tetrachromat artist Concetta Antico. https://munsell.com/color-blog/tetrachromat-artist-concetta-antico/
Broackes, J. (2010). What do the color-blind see? In J. Cohen & M. Matthen (Eds.), Color ontology and color science (pp. 291–405). The MIT Press. https://doi.org/10.7551/mitpress/9780262013857.003.0013
Burns, K. C. (2015). The color of plant reproduction: Macroecological trade-offs between biotic signaling and abiotic tolerance. Frontiers in Ecology and Evolution, 3, 1–4. https://doi.org/10.3389/fevo.2015.00118
Byrne, A., & Hilbert, D. R. (2010). How do things look to the color-blind? In J. Cohen & M. Matthen (Eds.), Color ontology and color science (pp. 258–290). The MIT Press. https://doi.org/10.7551/mitpress/9780262013857.003.0012
Cao, D., Pokorny, J., Smith, V. C., & Zele, A. J. (2008). Rod contributions to color perception: Linear with rod contrast. Vision Research, 48(26), 2586–2592. https://doi.org/10.1016/j.visres.2008.05.001
Chen, D.-M., Collins, J. S., & Goldsmith, T. H. (1984). The ultraviolet receptor of bird retinas. Science, 225(4659), 337–340. https://doi.org/10.1126/science.6740315
Cohen, J. D. (2009). The red and the real: An essay on color ontology. Oxford University Press.
Cosentino, A. (2014). FORS spectral database of historical pigments in different binders. E-Conservation Journal, 54–65. https://doi.org/10.18236/econs2.201410
Danilova, M. V., & Mollon, J. D. (2022). Bongard and Smirnov on the tetrachromacy of extra-foveal vision. Vision Research, 195, 107952, 1–7. https://doi.org/10.1016/j.visres.2021.08.007
De Vries, H. (1948). The fundamental response curves of normal and abnormal dichromatic and trichromatic eyes. Physica, 14(6), 367–380. https://doi.org/10.1016/0031-8914(48)90021-4
Dorment, R., & MacDonald, M. F. (Eds.). (1994). James McNeill Whistler: Tate Gallery, London 13 October 1994 - 8 January 1995; Musée d'Orsay, Paris 6 February - 30 April 1995; National Gallery of Art, Washington 28 May - 20 August 1995. Tate Gallery.
Fleming, S. M., & Shea, N. (2024). Quality space computations for consciousness. Trends in Cognitive Sciences, 28(10), 896–906. https://doi.org/10.1016/j.tics.2024.06.007
Galilei, G. (1960). The assayer. In S. Drake & C. D. O’Malley (Eds.), The Controversy on the Comets of 1618: Galileo Galilei, Horatio Grassi, Mario Guiducci, Johann Kepler (pp. 151–336). University of Pennsylvania Press.
Greenwood, V. (2012, June 18). The humans with super human vision. Discover. https://www.discovermagazine.com/mind/the-humans-with-super-human-vision
Hacker, P. M. S. (1987). Appearance and reality: A philosophical investigation into perception and perceptual qualities. B. Blackwell.
Hardin, C. L. (1993). Color for philosophers: Unweaving the rainbow (rev.). Hackett Pub. Co.
Hardin, C. L. (2014). More color science for philosophers. In D. Stokes, M. Matthen, & S. Biggs (Eds.), Perception and its modalities (pp. 379–390). Oxford University Press. https://doi.org/10.1093/acprof:oso/9780199832798.003.0016
Hering, E. (1964). Outlines of a theory of the light sense (L. M. Hurvich & D. Jameson, Trans.). Harvard University Press.
Higgins, J. (2022, February 19). The rare gift of seeing extra colors. Wall Street Journal. https://www.wsj.com/articles/the-rare-gift-of-seeing-extra-colors-11645246860
Hou, K. (2016, September 27). This lipstick was designed by a woman who can see 100 million colors. The Cut. thecut.com/2016/09/m-a-cs-liptensity-lipsticks-were-created-by-a-tetrachromat.html
Ings, S. (2007, March 7). You won’t believe your eyes: The mysteries of sight revealed. The Independent. https://www.independent.co.uk/news/science/you-won-t-believe-your-eyes-the-mysteries-of-sight-revealed-5332314.html#comments-area
Jackson, F. (1982). Epiphenomenal qualia. The Philosophical Quarterly, 32(127), 127–136. https://doi.org/10.2307/2960077
Jacobs, G. H., Williams, G. A., Cahill, H., & Nathans, J. (2007). Emergence of novel color vision in mice engineered to express a human cone photopigment. Science, 315(5819), 1723–1725. https://doi.org/10.1126/science.1138838
Jameson, K. A., Satalich, T. A., Joe, K. C., Bochko, V. A., Atilano, S. R., & Kenney, M. C. (2020). Human color vision and tetrachromacy (1st ed). Cambridge University Press.
Jameson, K. A., & Winkler, A. D. (2014). Preliminary research report on the results of Concetta Antico’s psychophysical color vision testing and its relation to her photopigment opsin genotype. https://sites.socsci.uci.edu/~kjameson/JamesonWinkler2014.pdf
Jameson, K. A., Winkler, A. D., Herrera Ortiz, C., & Goldfarb, K. (2015). The veridicality of color: A case study of potential human tetrachromacy. GLIMPSE Journal: The Art + Science of Seeing [Pre-Print], 12, 1–36.
Jordan, G., Deeb, S. S., Bosten, J. M., & Mollon, J. D. (2010). The dimensionality of color vision in carriers of anomalous trichromacy. Journal of Vision, 10(8), 12, 1–19. https://doi.org/10.1167/10.8.12
Jordan, G., & Mollon, J. (2019). Tetrachromacy: The mysterious case of extra-ordinary color vision. Current Opinion in Behavioral Sciences, 30, 130–134. https://doi.org/10.1016/j.cobeha.2019.08.002
Jordan, G., & Mollon, J. D. (1993). A study of women heterozygous for colour deficiencies. Vision Research, 33(11), 1495–1508. https://doi.org/10.1016/0042-6989(93)90143-K
Kuehni, R. G. (2014). Unique hues and their stimuli—state of the art. Color Research & Application, 39(3), 279–287. https://doi.org/10.1002/col.21793
Li, J., Feng, X., & Fan, H. (2020). Saliency-based image correction for colorblind patients. Computational Visual Media, 6(2), 169–189. https://doi.org/10.1007/s41095-020-0172-x
Locke, J. (1961). An essay concerning human understanding (J. W. Yolton, Ed.). Dent.
Macpherson, F. (2020). Novel colour experiences and their implications. In D. H. Brown & F. Macpherson (Eds.), The Routledge handbook of philosophy of colour (1st ed., pp. 175–209). Routledge. https://doi.org/10.4324/9781351048521-15
Mancuso, K., Hauswirth, W. W., Li, Q., Connor, T. B., Kuchenbecker, J. A., Mauck, M. C., Neitz, J., & Neitz, M. (2009). Gene therapy for red–green colour blindness in adult primates. Nature, 461(7265), 784–787. https://doi.org/10.1038/nature08401
Marshall, J., & Arikawa, K. (2014). Unconventional colour vision. Current Biology, 24(24), R1150–R1154. https://doi.org/10.1016/j.cub.2014.10.025
Matthen, M. (2005). Seeing, doing, and knowing: A philosophical theory of sense perception (1st ed.). Oxford University Press. https://doi.org/10.1093/0199268509.001.0001
Mollon, J. D., & Jordan, G. (1997). On the nature of unique hues. In C. Dickinson, I. Murray, & D. Carden (Eds.), John Dalton’s Color Vision Legacy (pp. 381–392). Taylor & Francis.
Nagel, T. (1974). What is it like to be a bat? The Philosophical Review, 83(4), 435–450. https://doi.org/10.2307/2183914
Newall, M. (2021). Painting with impossible colours: Some thoughts and observations on yellowish blue. Perception, 50(2), 129–139. https://doi.org/10.1177/0301006620988845
Pastor, J. (2009, September 16). Pastor, J. 2009, “scientists cure color blindness in monkeys,” , 16 September, . https://ufhealth.org/news/2009/scientists-cure-color-blindness-monkeys
Reutersvärd, O. (1950). The ”violettomania” of the impressionists. The Journal of Aesthetics and Art Criticism, 9(2), 106–110. https://doi.org/10.2307/426328
Robson, D. (2014, September 5). The women with superhuman vision. https://www.bbc.com/future/article/20140905-the-women-with-super-human-vision
Roque, G. (1996). Chevreul and impressionism: A reappraisal. The Art Bulletin, 78(1), 27–39. https://doi.org/10.2307/3046155
Ruskin, J. (1864). The elements of drawing. John Wiley.
Seaberg, M. (2014, December). Girl with kaleidoscope eyes. Vogue, 232–234.
Seth, A. (2022). Being you: a new science of consciousness (Paperback edition). Faber.
Stapledon, O. (2012). Odd John. Gollancz.
Stoughton, C. M., & Conway, B. R. (2008). Neural basis for unique hues. Current Biology, 18(16), R698–R699. https://doi.org/10.1016/j.cub.2008.06.018
Thoen, H. H., How, M. J., Chiou, T.-H., & Marshall, J. (2014). A different form of color vision in mantis shrimp. Science, 343(6169), 411–413. https://doi.org/10.1126/science.1245824
Thompson, E. (1992). Novel colours. Philosophical Studies, 68(3), 321–349. https://doi.org/10.1007/BF00694850
Valberg, A. (2001). Unique hues: An old problem for a new generation. Vision Research, 41(13), 1645–1657. https://doi.org/10.1016/S0042-6989(01)00041-4
Viénot, F., Brettel, H., Ott, L., Ben M’Barek, A., & Mollon, J. D. (1995). What do colour-blind people see? Nature, 376(6536), 127–128. https://doi.org/10.1038/376127a0
Wolchover, N. (2012, June 29). Your color red really could be my blue. https://www.livescience.com/21275-color-red-blue-scientists.html
Zeki, S. (1980). The representation of colours in the cerebral cortex. Nature, 284(5755), 412–418. https://doi.org/10.1038/284412a0
Zorpette, G. (2000, November 1). Looking for madam tetrachromat. https://archives.evergreen.edu/webpages/curricular/2006-2007/anp07/Looking%20for%20Madam%20Tetrachromat.htm
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