An intermingling of the senses creates not just a different way of perceiving the world, but a window into your past, like psychological amber.
By Meera Khare (the synesthete) and Apoorva Bhandari (the neuroscientist)
My consciousness is a constant stream of color. Whether I’m reading, texting a friend, or doing math homework, every letter or number I see comes swathed in its own characteristic hue. My 7’s are forest green, L’s are orange, and both A’s and 4’s are hot pink.
Growing up, I did not realize my experience was atypical until I read A Mango Shaped Space by Wendy Mass in middle school. The book tells the story of 13-year old Mia Winchell, who experiences synesthesia, a mingling of the senses. Mia involuntarily sees letters, numbers and even sounds in specific colors. The book described my experience perfectly except for one thing – my colors were different. Since then, I’ve wondered what gives every synesthete their own unique associations; why does the K look lavender to me, but blue for someone else? What neural process transforms an impersonal, black T into my vivid, lime green T?
An interesting aspect of my experience is that while two letters or numbers (often called graphemes by neuroscientists studying synesthesia) rarely share the same color, both my A and 4 are hot pink. As a classical pianist immersed in music from a young age, I recognized this alphanumeric pairing as the code “A4” representing the 440 Hz "Stuttgart pitch," an international tuning standard for musical ensembles and instruments. (If you’ve ever been to an orchestra concert, it’s the note that all the string instruments tune to at first.)
I’ve been exposed to this pitch and its alphanumeric code countless times. Was this a coincidence or a clue? I’ve always wondered whether my hot-pink link between A and 4 could actually be a result of my musical background and familiarity with Stuttgart Pitch.
In popular culture, synesthesia is commonly presented as a mental quirk, an amusing oddity, but I felt it was more. Last summer, I embarked on a quest to find answers. What I learned was remarkable and surprising: biology, culture, and chance conspire to produce persistent echoes of long-forgotten childhood experiences in the minds of synesthetes. We are walking, talking psychological time capsules. Synesthesia is not just a different way of perceiving the world, it is a different way of remembering and recording the world. This suggests that subliminal associations are more pivotal to the phenomenon than previously thought, and adds weight to the idea that we are all synesthetes to a certain degree.
It was the English polymath Francis Galton - known among other things for his controversial theory of eugenics - who put forth a theory of synesthesia in 1880. Galton correctly recognized that synesthesia was a hereditary condition. Almost one in two synesthetes report a first degree relative, like a parent, sibling, or child, with the condition.
But how does genetics change a synesthete’s brain? Over 20 years ago, as non-invasive brain imaging technology became available, scientists began seeking synesthesia’s neurobiological cause, and a menu of theories emerged. One notable theory comes from neuroscientists Vilayanur (V.S.) Ramachandran and Edward Hubbard. Writing in the Journal of Consciousness Studies in 2001, they proposed that in synesthetes, adjacent brain regions are cross-wired.
Their study of grapheme-color synesthetes (who experience letters, digits, or entire words in color) found that processing centers for letters and numbers happen to be right next to the processing center for colors in the human brain. That research, conducted at the University of California San Diego, indicates that everyone is born with hyperconnectivity between these brain regions; however, those who experience the phenomenon have a genetic mutation that reduces the degree of “pruning,” or stabilization of the connections between the brain regions.
Neuroscience may tell us why synesthetes see colored letters and numbers, but how do we explain which colors are assigned to letters and numbers? Nicholas Root, a psycholinguist at the University of Amsterdam, has been asking these questions, too.
“Biology is not making you see a red 5 versus a green 5,” Root explains. “Biology is making you see some color versus no color at all. The association itself comes from different sources, including the truly personal.” I (Meera) immediately thought of Stuttgart pitch’s connection with my A4 alphanumeric pairing. That’s where the influence of one’s environment comes in.
“If your family is a fan of the Oregon Ducks football team, and they have rooms filled with Oregon Ducks posters and jerseys and the logo with the yellow O, maybe your O is yellow because you grew up seeing a yellow O in your home all the time,” Root says.
In a study published in 2015 in PLOS ONE, researchers found that Fisher-Price refrigerator magnets had striking influence on synesthetic associations. There was even a synesthete whose color-letter pairings matched 25 of the 26 letters in the magnet set. Root, who was not involved in this study, describes this phenomenon as “…something the brain latches on to. The colors a synesthete experiences are just a reflection of the environment that they grew up in.”
We’d like to suggest an analogy to another natural phenomenon: fossils preserved in amber. As you peer into a piece of golden amber, you are looking into the past. You may see an extinct bug, a prehistoric flower, or a dinosaur feather, a tiny relic from the past preserved in a golden time capsule. Synesthesia works similarly. Genetics and neurobiology produce the resin, perhaps the hyperconnectivity. But what the resin captures — the specific associations — come from the synesthete’s individual environment and experiences. The perceptual intermingling that the synesthete experiences is like a piece of psychological amber that has trapped an environmental influence of their past.
Most often, pieces of amber contain something mundane; they may preserve only dirt or air bubbles, but those things can be significant, too, it can tell us about the past. By analogy, most synesthetic associations also have trivial origins. Is L orange because of a logo of a brand I was exposed to a lot as a child? Is K
lavender because of a poster on my bedroom wall? The source material being personal, a connection that might seem trivial to others may be significant for the synesthete in what it tells them about their past.
Sometimes, though, pieces of amber contain something extraordinary, like a spider attacking a wasp or an insect hatching out of an egg. Synesthesia too, can capture something extraordinary – bits of our culture at large. As with the Fisher Price magnets, when the source of the associations is cultural, you see similar associations over a larger group. “What's nice about culture is that it's consistent between people,” Root says.
In a 2019 study, when Root was a PhD student at the University of California San Diego, he and his colleague made a striking discovery. They tested 5 to 7-year-old girl synesthetes and found that they tended to associate the first initial of their first names with the color pink. Synesthetic adult women internalized the association and also tended to associate their first initial with pink. When prompted to assign colors, even if the association took some thought, non-synesthetic adult women associated their first initial with their current favorite color, which differed from one person to the next; they had not internalized an association with pink.
As Root said, “In American culture, when you're five or six years old and you're a girl, perhaps you may learn that pink is for girls.” Many people then internalize it, retaining the association in the amber of their minds. They do so even if they might no longer think that pink is for girls. “In adult synesthetes, we found that the color they experience is not based on something they believe today. It’s based on something they believed when they were six years old, manifesting itself into their lifelong associations.” In this case, the psychological amber captured something deeper about all of us – an implicit cultural bias in our society.
I, too, associate the first letter of my name, M, with a pinkish color (specifically magenta). It was a revelation to learn that my synesthetic associations could say something about how culture may shape a child’s view of the world. Indeed, through its unblinkered mechanism, synesthesia may reveal aspects of our culture that we are so inured to, we no longer notice them.
Everyone’s brain registers these associations. But while they are malleable and updated in most of us, in synesthetes they have been frozen in place. “I think there's something special about actually seeing it…what makes synesthetes special is that they actually see these associations, and there's something about actually seeing something that makes it harder for them to change their minds about it,” Root explains.
For him, synesthesia provides a window inside people’s brains by bringing unconscious associations to the surface. “I don't believe that any synesthetic color is random. I think that when synesthetes tell us what color they're experiencing, we are actually looking inside their mind and that's an opportunity you don't get with any other person in the world.”
Could the idea of subliminal associations apply to non-synesthetes as well? One clue comes from the world of marketing, according to anthropologist David Howes, co-director of the Centre for Sensory Studies at Concordia University Montreal. For example, over time “people came to associate the particular shade of blue used by Tiffany’s jewelers with luxury,” he explained in a Q&A in Slate. “Likewise, in the United Kingdom, purple sells chocolate because those who have grown up around Cadbury’s Dairy Milk bars associate the color with gustatory pleasure.” Associations vary from one culture to the next. “In China, the color white is often identified with a harsh, foul odor. In the West, white is usually identified with soft, sweet smells,” Howes told Slate.
Reactions to odor vary across generations. In one study from Howes’ group, researchers showed that those born in the 1920s, ‘30s and ‘40s felt nostalgic at the smell of burning leaves, hot chocolate, cut grass and ocean air. Those born during the 1960s and ‘70s felt nostalgia when smelling Downy fabric softener, Play-Doh, suntan oil, and Cocoa Puffs.
Sensual associations infiltrate politics, as well. “The phenomenon of nationalism,” for instance, “can never be adequately comprehended simply as an adherence to certain political ideals or social communities. It is always at the same time an attachment to particular tastes, smells, sounds, and insights, which themselves carry cultural values and personal memories,” Howes writes in Ways of Sensing: Understanding the Senses in Society, co-authored with cultural historian Constance Classen.
These associations, found in the general population, suggest that we may all be silent synesthetes. The unconscious biases we struggle to understand are echoes of learned associations from our past. Synesthetes like me have a superpower: the ability to see our learned associations in vivid, stable perceptual experiences. These synesthetic associations are persistent echoes of a long-forgotten childhood, experiences frozen in place by a genetic predisposition — a kind of psychological time capsule providing a unique window into the past.
Non-synesthetes can take a more effortful route to explore their own unconscious associations, preferences, and biases. These faint shadows of the past may not have the same vibrancy of a true synesthete’s perceptions, but will still reveal themselves when inner experience is examined under a meditative lens.
May 11, 2023