A is a pretty boring gray-tan. B is brown. C is where it gets good: the exact color of Crayola’s “Macaroni and Cheese” crayon. My initials, J and M, are especially vibrant! I could go on; letters, numbers, days, and months are all permanently linked to specific colors in my mind. This is just one manifestation of the fascinating neurological condition called synesthesia.

My personal alphabet. Some of these aren’t exactly right, because the colors in my mind don’t always exist on the visible spectrum.

Put simply, synesthesia is the combining of the senses.

cover of Struck by Genius by Jason Padgett

Associating written forms with certain colors, known as grapheme-color synesthesia, is one of the most common. Chromesthesia, seeing shapes and colors while hearing a sound, is another example. Some people might taste mint and automatically feel like they’re touching a cool, smooth surface. Some, like Jason Padgett, might see the underlying geometry of the world. Others might feel that Tuesday exists in space right at eye level, slightly to the left. Still others might perceive numbers and letters as having gender and personality. While anyone could imagine these things, a synesthete’s sensory experiences are automatic, irrepressible, and consistent over long periods of time.

cover of The Girl Who Heard Colors by Marie Harris

Synesthetic kids these days are lucky; I didn’t have a nifty picture book like Marie Harris’ The Girl Who Heard Colors to clue me in. The extra connections solidify in a synesthete’s brain long before one becomes consciously aware of them. It’s simply the way the world is. Many people never think to mention it because they assume it’s the same for everyone else. The kids who do mention it are often quickly shut down by mocking peers or exasperated adults, and learn to keep their synesthetic experiences to themselves. Others, like me, happily did math with a yellow 7, a blue 4, a green 6, never imagining numbers could be any other way. I didn’t hear the term synesthesia until I was in high school, and it took me several more years to realize that I actually had it. Harris’ book is an excellent introduction to synesthesia for children and adults alike. Straightforward and engaging, it can be eye-opening for young synesthetes and informative for their non-synesthetic friends and family.

Synesthesia research is still a relatively new field of science.

cover of Our Senses by Rob DeSalle

What seems like a rarity might be the norm for infants. In his book Our Senses, Rob DeSalle details a study that tested sensory processing in babies. Their measurable reactions to bright lights and loud noises imply that the two were sometimes interchangeable. This could be because developing brains have an overabundance of neurons, which are subsequently “pruned” as pertinent connections are reinforced. Sorting sensory stimuli into appropriate categories is one of the many things a baby must learn. Could synesthesia be the vestiges of unconventional neural pathways?

DeSalle’s book works to reframe our understanding of the way humans sense things. He explores crossmodality, or how one sense affects the others. Even in non-synesthetes, there are surprisingly consistent ties between certain senses. For example, most people associate a sweet taste to a high pitch, while low pitches are associated with bitterness. The infamous “Kiki and Bouba” test is an easy way to see how certain sounds are subconsciously connected to different shapes. While true synesthesia is much more varied and arbitrary, any new discovery about human perception is one step closer to understanding this phenomenon.

cover of Musicophilia by Oliver Sacks
An exploration of how music affects the brain

In his book Musicophilia, Oliver Sacks mentions a survey of 1,700 individuals where 1 in 23 had synesthesia. That’s downright commonplace! Yet synesthesia was dismissed by the scientific community for centuries. Sir Francis Galton was the first to do a formal study in the 1890s, but before research could gain any momentum, behaviorism took the psychology world by storm. Interest in such an unquantifiable experience as synesthesia was quashed.

Thankfully, neurologist Richard Cytowic sparked the contemporary resurgence of synesthesia research in the 1980s. He and others like David Eagleman and V.S. Ramachandran devised clever ways to conduct empirical testing, finally giving synesthesia the credibility it needed to be recognized as a physical neurological condition. Ramachandran’s book The Tell-Tale Brain (available on Libby) devotes a whole chapter to his early examinations. These few modern researchers were truly starting from scratch. Simply confirming synesthesia’s existence was a step forward, as many simply assumed it was some hysterical flight of fancy or hallucination. The news eventually caught on, and as awareness spread, people everywhere finally had a name for their experiences.

cover of A Mango-shaped Space by Wendy Mass

By the mid-2000s, synesthesia had made its way into fiction for young readers like me.

In A Mango-Shaped Space, author Wendy Mass uses synesthesia as the driving force of her poignant coming-of-age story. The young protagonist takes it upon herself to explore her sensations in a time when very few people would have recognized it for what it is. It is one of the first books to prominently and intentionally feature the condition.

The Name of this Book is Secret by Pseudonymous Bosch

The Secret Series by Pseudonymous Bosch takes a very different route. Book 1, The Name of This Book is Secret, is simply a wacky adventure. But each book is themed around one of the five senses, and as the the overarching mystery unravels, synesthesia is revealed as an intriguing element. Since the series is naturally outlandish, synesthesia doesn’t stick out as a particularly odd detail. It fits right into the fiction with the added bonus of being completely true.

As it becomes common knowledge, synesthetic protagonists have begun to show up a little more frequently, especially in mystery/thrillers. Well-meaning authors often frame it as a sort of clairvoyance, rather than a simple sensory response to external stimuli. Nevertheless, the more the word itself is thrown around, the more people have the chance to look it up and learn something new!

Synesthesia shows up in the most likely—and unlikely—places.

Famed abstract expressionist painter Wassily Kandinsky had synesthesia. Is it any surprise that many synesthetes are drawn to the arts? The music industry boasts even more examples: Jack and Ryan Met of AJR, Pharrell Williams, Charli XCX, Lorde, Billy Joel, and Billie Eilish, to name a few. This is not to say that every synesthete is destined for a grand, creative career; it is but one of the many factors that influences a person’s sensibilities.

Sir Robert Cailliau, computer scientist and pioneer of the World Wide Web, has grapheme-color synesthesia. When coming up with a name for the web, he worried that “World Wide Web” was too clunky. But W happened to be a color he liked—green—so the name stuck around. And that’s why the original logo for the World Wide Web is green!

“Frankly, I feel insane/ But you say you feel the same/ And suddenly it’s like ‘Hey, I’m not crazy!'”

AJR, Wow, I’m Not Crazy

Synesthesia remains a marvelous mystery.

Synesthesia is an inherently personal experience. Sometimes it’s nothing more than a fun party trick or a useful mnemonic aid, sometimes it informs creative expression and influences personal taste, sometimes it’s a dazzling wonder, and sometimes it overwhelms. Despite the increased possibility of sensory overload, synesthesia is not considered a disorder and does not require a formal diagnosis. If you notice you have it, then that’s it, you have it. The majority of synesthetes love their extra sensations and would be sad to lose them.

Despite the recent strides forward in research, its genetic and neurological underpinnings still elude us. However, synesthetes worldwide are finding community like never before as the internet brings us closer together (thanks, Sir Robert!). As more people find a name for their unique way of looking at the world, will we discover that synesthesia is more common than we ever imagined? My hope is that this blog post has taught you something new, or maybe even taught you something new about yourself.

Additional Resources

Cytowic, Richard E. (2003). The Man who tasted shapes. MIT Press.
Cytowic, R. E., & Eagleman, D. M. (2009). Wednesday is indigo blue: Discovering the brain of synesthesia. MIT Press.
Duffy, Patricia Lynne. (2001). Blue cats and chartreuse kittens: how synesthetes color their worlds. Times Books.
Eagleman, David. (2020). Livewired: The inside story of the ever-changing brain. Pantheon Books.
Eagleman, David. synesthete.org
Nerenberg, Jenara. (2020). Divergent mind: thriving in a world that wasn’t designed for you. HarperOne.
Ramachandran, V. S. (2011). The tell-tale brain: a neuroscientist’s quest for what makes us human. W. W. Norton.
Seaberg, Maureen. (2011). Tasting the universe: people who see colors in words and rainbows in symphonies: a spiritual and scientific exploration of synesthesia. Pompton Plains.
Tammet, Daniel. (2007). Born on a blue day: Inside the extraordinary mind of an autistic savant. Thorndike press.
Ward, Jamie. (2008). The frog who croaked blue: Synesthesia and the mixing of the senses. Routledge.