Inside the Synesthetic Brain

By Emily Cho ‘27  • Nov 18, 2025

On July 16, 1915, American painter Charles Burchfield recorded the perceptions he was experiencing in his journal,

“It seems at times I should be a composer of sounds, not only of rhythms and colors. Walking under the trees, I felt as if the color made a sound … Listen long to the singing of the telephone poles… Each pole has a distinct tone, a steady throbbing sound – the poles, once trees, still are full of life which is expressed in this pulsating sound.”

(J. Benjamin)

To illustrate this perception, he created a code of symbols to project these sounds and emotions into his paintings, but was oblivious to the fact that his senses had a term, synesthesia.

Accounts of synesthetes that were shunned or even diagnosed as being mad exist across centuries- as it is said that Van Gogh was by his piano teacher. But the sensations they experience are real, tangible perceptual abilities, and are discernible in contemporary artists. Frank Ocean is an eminent example; his debut studio album “Channel Orange” was named in reference to his perception of the summer in which he fell in love, as he elucidated “everything felt orange” when he first fell in love. Synesthesia isn't a mere descriptive metaphor or association, it’s the joining of senses and has been demonstrated through the use of fMRI brain scans. 

What is Synesthesia?

Synesthesia is a neurological condition or a phenomenon where the brain directs sensory information through multiple unrelated senses, causing one to have more than one sense activated simultaneously. This involuntary and consistent experience causes individuals to link senses in unique ways, such as “seeing” a specific, definite color for letters and music or “tasting” textures like ‘round’ when they eat food. Synesthesia isn’t a disease or a medical condition, rather, it can be linked to advantages like strong memory or creative abilities.

Types of Synesthesia

There are over 60 different and distinct types of synesthesia. Despite individuals having the same condition, so many possible combinations between your senses and perception abilities exist. Here are some of the most common types of synesthesia:

• Grapheme-color synesthesia.

• Auditory-tactile synesthesia.

• Day-color synesthesia.

• Hearing-motion synesthesia.

• Mirror-touch synesthesia.

• Time-space synesthesia.

• Visualized sensations.

Here is an excerpt from the Russian writer Vladimir Nabokov’s autobiography Speak, Memory, where he describes the experience of being a Grapheme-color synesthete:

“…I present a fine case of colored hearing. Perhaps “hearing” is not quite accurate, since the color sensations seem to be produced by the very act of my orally forming a given letter while I imagine its outline. The long a of the English alphabet … has for me the tint of weathered wood, but a French a evokes polished ebony…Passing on to the blue group, there is steely x, thundercloud z, and huckleberry k … I see q as browner than k, while s is not the light blue of c, but a curious mixture of azure and mother-of-pearl … in the green group, there are alder-leaf f, the unripe apple of p, and pistachio t.”

Richard E. Cytowic, a neurologist and synesthesia researcher, describes his perceptions as a taste-touch synesthete:

“When I taste something with an intense flavor … I also feel it on my face and in my hands. A sensation sweeps down my arm and I feel weight, shape, texture, and temperature as if I’m actually grasping something.” 

Why does synesthesia happen?

Although experts can't fully comprehend why synesthesia happens, they predict that synesthetes are “neurodivergent”- which means their brain develops and works in a different way from “neurotypical people”, whose brains develop and work as expected. In the neurodivergent brain, the neurons responsible for different senses, such as letters and colors, are more “talkative” with one another compared to the brain of non-synesthetes. In a 2013 study, 20 grapheme-color synesthetes and 19 control subjects, while lying on an MRI machine, were asked to watch or hear the episodes of Sesame Street, a children's television show full of letters and numbers. The results demonstrated that these synesthetes have a higher cross-activation between the areas of the brain responsible for letters and those responsible for colors. As a result, the neurons in these two areas are more “talkative” to each other than nonsynesthetes, in which when some individuals only listened to a Sesame Street character mention a letter causes visual areas of the brain to activate and light up on the scan.