“And Carly — you’re blue.” I looked up from my cheesy pasta to see Clara pointing at me from across the dining hall table. “‘C’, of course, is pink, but you are definitely blue.”
My pasta was delicious, but it was no longer the most interesting part of my lunch experience. Clara continued to go around the table, assigning a color to each person. She then explained that it wasn’t just people. Her mind tinted nearly every word she encountered, often by its first letter. I was blue because to Clara, my personality was blue, but “c” is generally pink — just as “t” is orange, “b” is blue, “e” is yellow, etc.
Clara has synesthesia. Based on its Greek roots, synesthesia literally means “joined perception” (Cytowic, 2006, 371). People who experience this — often called synesthetes — will associate senses such that a sound, for example, could be tasted or seen. Studies have shown that ⅔ of synesthetes experience the condition upon reading, thinking, or hearing some letter, word, or number that stimulates a sense not typically associated with the given input. (Cytowic, 2006, 371). All people have some form of cross-modal abilities whereby our senses interact with one another — for example, a certain sound might sometimes trigger a taste (Cuskley, Kirby, 2013, 3). Push comes to shove, I could tell you that the word “cave” is probably black, and “chair” is purple. But I do not automatically or naturally make these associations. Synesthetes, on the other hand, do.
“I associate people, words, and days of the weeks with colors. It’s not really related to sounds—more just to words I see. I even do it with places or subjects. I think it’s very associated with the letter of the alphabet. I don’t know the mechanism for why it changes, but there’s definitely a connection between the letters and colors.” — Clara (Interview, April 2021)
Two of the most common types of synesthesia relate to language, whether written or spoken (Cytowic, 2006, 371). Like Clara, these synesthetes will hear or see a word and associate the input with a color. After our dining hall adventure, I conducted a sort of study on Clara. It was highly inexact and likely poorly done, but we had a nice time (Figure A).
More importantly, however, I was able to see how my friend’s synesthesia relates to a broader body of research with which I have since engaged. In studying synesthesia’s relationship to language and color, I developed two related questions: how do synesthetes color their words, and what — if anything — can these patterns tell us about language cognition of synesthetes and non-synesthetes alike?
Synesthesia and language
Synesthesia comes in a variety of forms, but I am most interested in the relationship between color and language. People with synesthesia might color words they hear and see. Indeed, the most common form of synesthesia is grapheme-color synesthesia, whereby letters or numerals trigger a color association (Cytowic, 2006, 371). In this context, a grapheme references the smallest distinctive unit that is in a writing system (Kadosh and Henik, 2007, 23). (Cytowic, 2006, 371). Less common is phoneme-color synesthesia, by which phonemes, or contrastive sounds in a language, are responsible for determining the color (Cytowic, 2006, 371). Only 10% of synesthetes report this type of synesthesia, in contrast to the nearly 70% who report grapheme-color synesthesia(Cytowic, 2006, 371).
However, people who experience grapheme-color synesthesia may also color words that they hear, but these visualizations tend to be based on written letters, rather than sounds (Kadosh and Henik, 2007, 23). For example, such synesthetes would likely assign the same color to “cite” and “cat,” despite the fact that the “c” makes a different sound in each word. (Kadosh and Henik, 2007, 23). Researchers attribute this finding to the fact that associations between letters and colors generally develop before a child learns a writing system(Asano and Yokosawa, 2013, 4,5). Thus, when a child learns to read and write, she simply maps the associated sound onto the letter (Asano and Yokosawa, 2013, 4,5).
How synesthetes decide their colors
Although synesthetes vary in how they assign colors to words, there are certain patterns to the colors they choose, and it is believed that a number of factors contribute to the ultimate hue on which a person decides. To the first point, grapheme-color synesthetes overlap in what color they assign to letters. For example, the letter “A” is more likely to be red across synesthetes (Figure B).
A number of factors have been shown to impact the coloring process in the minds of synesthetes. For example, synesthetes generally decide the color of the word based on its first letter, but other factors might also influence the final hue (Cytowic, 2006, 371). Researchers found that synesthetes colored the word “ether” faster than they did “ethos,” implying that the multiple “e”’s prompted an even more immediate coloring of the former (Mankin, 2019, 2). Stress can also play a role in how a synesthete hues a word. Synesthetes color “convict” in its noun form — ‘con-vict — differently than they do in its verb form — con-’vict. (Kadosh and Henik, 2007, 25). Additionally, synesthetes often associate more than one color with a given word (Mankin, 2019, 3). As a result, synesthetes have reported frustration that many researchers ask them to assign only one color to each word (Mankin, 2019, 3). In reality, many synesthetes report seeing colors side by side, as opposed to visualizing only one color that is a blend of two different hues they associate with the word (Mankin, 2019, 3).
Mental associations may also determine the color of a word, regardless of letters. For example, one study documented a participant who colored the names of familiar people based on the person’s characteristics, even if the letters that made up the person’s name would generally induce a different hue (Cytowic, 2006, 375). This was certainly true of Clara with regards to my name. Like she said, “c” is usually pink, but I am blue because my personality aligns more with that color. However, the color of a person’s name might change as she gets to know them. For example, Clara thinks a girl in our college—Abigail — is red. Clara knows Abigail, but she does not know her particularly well. As a result, Clara colors Abigail based on her default association between “a” and red. Clara said that should she get to know her better, Abigail might go from red to a different color based on her personality. (Figure A also exhibits other factors which overrode the first letter’s influence on Clara. For example, “clementine” is orange because the fruit is orange, according to Clara, even though “c” is generally pink.)
While research is limited, it is also conceivable that unique neurological connections in some people’s brains can at least partially explain synesthesia. Synesthetes might cross activate regions of the brain based on “either unusual projections or lack of inhibition between them,” meaning that they form specific links between different areas of the brain (Cytowic, 2006, 372). For example, a part of the brain responsible for processing graphemes is next to the V4 area in the brain which relates to color perception (Cytowic, 2006, 372). Thus, the proximity of these two regions might lead to hyper-connectivity between them, which could be one explanation for why grapheme-color synesthesia is so common (Cytowic, 2006, 372). Again, research in this area is incredibly limited, and it is unclear why some, although not all brains, experience this kind of close connectivity. More research is needed before any solid conclusions can be made about neural processes and synesthesia.
What synesthesia can tell us about language processing
Research relating synesthesia to general cognitive processing is limited, but many linguists are optimistic that the processes through which synesthetes associate colors with words might have broader implications for linguistic cognition in general (Mankin, et. al, 2016, 1). In part, linguists believe we can connect information about synesthetes to non-synesthetes based on research showing that people with synesthesia and people without synesthesia still tend to associate letters with the same colors. A Simner et. al, study from 2005 prompted synesthetes and non-synesthetes to assign colors to words. This study found that across both groups, “a” is generally red, “b” is blue, and “c” is yellow (Simner et. al, 2005, 1071). Of course, the non-synesthetes do not naturally associate colors with words and only did so because the study demanded it of them. Still, this finding suggests that regardless of whether a person experiences grapheme-color synesthesia, some part of human cognition causes both synesthetes and non-synesthetes to color these letters similarly (Simner et. al, 2005, 1071).
But while some researchers are optimistic that synesthesia can reveal information about general cognitive functioning, there are still marked differences between how synesthetes and non-synesthetes assign colors and, possibly, process words in general. For example, the Simner et. al study — the same one which found overlaps between the coloring of “a,” “b,” and “c” — found that synesthetes associated common graphemes with common color terms, but non-synesthetes showed no such tendency. Non-synesthetes often assigned colors to words if the word sounded like the color — a tendency synesthetes have as well, but on a much smaller scale (Simner et. al, 2005, 1082). Non-synesthetes were also more likely to assign common colors to words presented to them at the beginning of their trial and less common colors to words presented at the end of their trial (Simner et. al, 2005, 1082). Synesthetes were much more consistent in how they assigned colors, whether the word came at the beginning or end of the trial (Simner et. al, 2005, 1082). These findings make clear that we must proceed with caution when making general assumptions about language processing based on how synesthetes assign colors to words.
The future of research on synesthesia and language
While researchers have conducted more studies on synesthesia and language in recent years, there is much to be learned about the phenomenon in general as well as what it might be able to tell us about language and cognition. Future studies could illuminate whether the tools synesthetes use to assign colors to words have any bearing on how all humans — synesthetes and non-synesthetes alike — understand language.
For example, synesthetes generally prioritize the first letter in words to determine color, but sometimes they prioritize other factors such as stress or mental associations with the word, as I presented above. What — if anything — could these findings tell us about how all brains conceptualize language and what factors we prioritize in assigning meaning to words? Other general questions could include: why does synesthesia develop in some people but not others? How does synesthesia vary across speakers of different languages?
To the best of my knowledge, Clara is the only one of my friends with synesthesia. She exhibits many of the same characteristics as other grapheme-color synesthetes; “A” is red to her, and her familiarity with a person might change how she colors them. So while each case of synesthesia is unique, there are overlaps between how people sometimes use language to assign colors to words. Further, there are even some similarities between non-synesthetes and synesthetes in studies that force the former to assign colors to words. Ultimately, Clara’s mind confuses me. I cannot imagine seeing “Tuesday” or “gust” as colors. Even so, research suggests that the peculiarities of Clara could help us understand how synesthetes and non-synesthetes alike process language. We could all stand to learn a little more about Clara’s colors.
Asano, M., & Yokosawa, K. (2013). Grapheme learning and grapheme-color synesthesia: toward a comprehensive model of grapheme-color association. Frontiers in human neuroscience, 7, 757.
Cuskley, C., & Kirby, S. (2013). Synesthesia, cross-modality, and language evolution.
Cytowic, R. E. (1989). Synesthesia and Language. In Synesthesia (pp. 177–189). Springer, New York, NY.
Kadosh, R. C., & Henik, A. (2007). Can synaesthesia research inform cognitive science?. Trends in cognitive sciences, 11(4), 177–184.
Mankin, J. L. (2019). Deepening understanding of language through synaesthesia: a call to reform and expand. Philosophical Transactions of the Royal Society B, 374(1787), 20180350.
Mankin, J. L., Thompson, C., Branigan, H. P., & Simner, J. (2016). Processing compound words: Evidence from synaesthesia. Cognition, 150, 1–9.
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Simner, J., Ward, J., Lanz, M., Jansari, A., Noonan, K., Glover, L., & Oakley, D. A. (2005). Non-random associations of graphemes to colours in synaesthetic and non-synaesthetic populations. Cognitive neuropsychology, 22(8), 1069–1085.