Synesthesia, Literature and Art

The use of drugs is often associated with the consciousness-expanding experiences and heightened sensibility described in religious revelations and visions of utopia. But does that mean all users of hallucinogenic drugs become synesthetes, able to perceive uncommon collaborations of several senses at once? The effects of depressant, stimulant, and hallucinogenic drugs on human perception and thinking is well-studied, as evidenced by the large volume of publications on the subject. Browsing through this literature, one finds references to drug-induced synesthesia in two chambers of the library: the science and literature rooms.

In the literature room I followed with delight the tracks of poets and novelists as they took their perceptual experiments to the edges of human experience. After reading wild descriptions by poets proclaiming the merits of their drug-induced synesthesia, I studied the pharmacology and neurology of the same experiences and compared notes. One thing became immediately clear: There is, without a doubt, a special relationship between drugs and synesthesia. But that relationship turns out to be quite different from what I expected.

In 18th-century England, opium was considered a normal medicine and was used in much the same way that people use aspirin today: Opium was considered a good remedy for pain, fatigue, and depression and could be obtained at the local shop. It was also the drug of choice for dealing with sleep difficulties. Several English writers and poets of the Romantic period wrote about their opium experiences, including Thomas De Quincey, Samuel Taylor Coleridge, John Keats, George Crabbe, and Francis Thompson. Their descriptions sometimes include visions that remind me of contemporary reports by synesthetes. For instance, the poet and opium addict Francis Thompson noted on one occasion that he saw the sun rise “with a clash of cymbals”; on another occasion, he described how “tunes rose in twirls of gold” when “light through the petals of a buttercup clanged like a beaten gong.” He also heard “the enameled tone of shallow flute, and the furry richness of clarinet.”

Many of these poets romanticized the virtues of taking opium. Samuel Taylor Coleridge, for one, proclaimed that his poem “Kubla Khan” was composed in a flush of opium-induced inspiration; when he woke up, all he had to do was write it down.

Thomas De Quincey distinguished himself by studying the effects of his opium intake, which he drank in the form of laudanum, an alcoholic tincture of the narcotic. By means of this self-study, he introspectively investigated the effects of the drug on his perceptions, hallucinations, and daydreams and reported his “findings” in “Confessions of an English Opium-Eater,” published in 1821.

De Quincey concluded that opium-induced visions were produced by the dream faculty in the human mind. He believed that the intake of opium stimulated the dream faculty, which in a waking person produced memories and emotions in symbolic patterns that are seen under the influence of the drug. He called those experiences “involutes.”

According to De Quincey, an involute is a complex feeling made up of memories, impressions, and symbols that involuntarily appear to the mind’s eye. The way he presents the “involutes” makes them sound to me like synesthetic perceptions in which sensory elements such as images and sounds mix to form new perceptual unities. Unfortunately, however, De Quincey was not very specific in his descriptions, so they could be taken as either intellectual constructs or synesthetic perceptions. Fortunately, other drug-experimenting writers were more specific in their descriptions of drug-induced perceptions, perceptions that resemble our current notions of synesthesia.

The gothic writer Edgar Allan Poe produced an impressive oeuvre that explored the dark sides of human feelings, all the while assisted by the alcoholism and drug addiction that eventually led to his early death. Drugs played an important role in his explorations of the human soul and likely opened new perceptions and experiences to him, including his becoming aware of his synesthetic perceptions. In his short story “A Tale of the Ragged Mountains,” Poe describes, through his character Augustus Bedloe, the effects of morphine on his sensibility:

‘’I n the meantime the morphine had its customary effect, that of enduing all the external world with an intensity of interest. In the quivering of a leaf, in the hue of a blade of grass, in the shape of a trefoil, in the humming of a bee, in the gleaming of a dewdrop, in the breathing of the wind, in the faint odors that came from the forest, there came a whole universe of suggestion, a gay and motley train of rhapsodical and immethodical thought.”

Poe’s poems are dominated by sensory symbols for the human heart that include his use of darkness, night, cold, and sound (frightening knocks on the door and the squeaking of open windows). The darkness itself evokes synesthetic impressions in him. Poe hears sounds in the shades of black and gray. In his early poem “Al Araaf,” this type of synesthesia steps forward and identifies itself in the second and last lines of the following excerpt:

“Sound loves to revel in a summer night;

Witness the murmur of the grey twilight

That stole upon the ear in Eyraco,

Of many a wild star gazer long ago—

That stealeth ever on the ear of him

Who, musing, gazing on the distant dim,

And sees the darkness coming as a cloud—

Is not its form—its voice—most palpable and loud?”

The murmuring of the gray twilight and the volume of the darkness is almost tangible. The darker the sky, the louder the sound. Poe’s synesthesia shows similarities with the reports of synesthetes who perceive high-pitched sounds as light and low-pitched sounds as dark. Poe was well aware of his perceptual capacities, as evidenced by a footnote to part II of “Al Araaf ”: “I have often thought I could distinctly hear the sound of darkness as it stole over the horizon.” He even seems to have been aware of the bidirectional nature of his synesthesia, for he wrote in the Democratic Review of November 1844: “The orange ray of the spectrum and the buzz of the gnat affect me with nearly similar sensations. In hearing the gnat, I perceive the color. In perceiving the color, I seem to hear the gnat.”

Poe’s “dark” poems and unconventional way of life inspired many poets, including the French poet Charles Baudelaire in Paris some decades later. One of the themes that Baudelaire would elaborate on was that of drugs, sensibility, and synesthesia.

In France, Baudelaire’s poem “Correspondences” in the volume “Les Fleurs du Mal (Flowers of Evil),” published in 1857, started a new romantic interest in synesthesia. The poem would become paradigmatic for poets of the Symbolist movement, who tried to discover a higher, spiritual reality by studying sensory correspondences.

“Correspondences”

Nature is a temple in which living pillars

Sometimes give voice to confused words;

Manpasses there through forests of symbols

Which look at him with understanding eyes.

Like prolonged echoes mingling in the distance

In a deep and tenebrous unity,

Vast as the dark of night and as the light of day,

Perfumes, sounds, and colors correspond.

There are perfumes as cool as the flesh of children,

Sweet as oboes, green as meadows

—And others are corrupt, and rich, triumphant,

With power to expand into infinity,

Like amber and incense, musk, benzoin,

That sing the ecstasy of the soul and senses.”

Baudelaire’s idea of correspondences is slightly different from the current meaning of synesthesia. He related the perception of sensory correspondences to a state of mind where various sensory impressions (perfumes, colors, sounds) corresponded to one another. The perception of a perfume evoked, in other sensory domains, coolness, sweetness, and greenness. And although these qualities were physically distinct, in his perception they were related in the sense of corresponding or talking with each other. He interpreted these correspondences as a voice from a deeper spiritual level of reality.

Baudelaire was inspired by the philosophy of Emanuel Swedenborg, an 18th-century Swedish scientist and philosopher who believed that sensory correspondences in the natural world mirrored correspondences in the spiritual world. Sensory correspondences would reveal not only the unity of the senses but also the unity of the spiritual world.

But what role did Baudelaire reserve for drugs in this vision? In his book of essays, “Les paradis artificiels (Artificial Paradises),” Baudelaire reported extensively on his investigations into the effects of drugs on perception. According to him, the use of hashish brought a person into a state of mind that had an intensifying impact on sensory experiences. He wrote that in a drugged state, he was able to perceive more sensory details with heightened emotional awareness. He believed that when the senses were more open to new stimuli — a state of mind called “hyperesthesia,” or hypersensibility — new correspondences could be revealed. Hypersensibility revealed a deeper layer of consciousness, one in which the sensory qualities had not yet been separated.

The effect of smoking hashish was to uncover them: He wrote that he perceived colors, smells, sounds, and tactile impressions more intensely and as interrelated when he was under the influence of hashish. Perceived correspondences such as colored sounds and musical colors that were placed in the category of temporary hallucinations by his contemporaries were taken as serious perceptions of a deeper layer of consciousness by Baudelaire. Intoxication created by drugs could lead to a mental state of hyperesthesia in which correspondences such as colored sounds and musical colors, appeared:

“It is, in fact, at this period of the intoxication that is manifested a new delicacy, a superior sharpness in each of the senses: smell, sight, hearing, touch join equally in this onward march; the eyes behold the Infinite; the ear perceives almost inaudible sounds in the midst of the most tremendous tumult. It is then that the hallucinations begin; external objects take on wholly and successively most strange appearances; they are deformed and transformed. Then—the ambiguities, the misunderstandings, and the transpositions of ideas! Sounds cloak themselves with color; colors blossom into music.”

Baudelaire participated in a unique experiment of the Club de Hachichins in Paris in 1845. A painter, poet, and musician named Joseph Ferdinand Boissard de Boisdenier organized monthly gatherings that he named “fantasias” held in his luxury apartment in the Hôtel Pimodan on the île Saint-Louis. The French poet and journalist Théophile Gautier, who was a close friend of Baudelaire’s, saved one such invitation. It reads: “Dear Théophile, next Monday the third of the ninth [1845] hashish will be taken at my place under supervision of Moreau and Roche.”

Jacques-Joseph Moreau and Aubert Roche were physicians who were studying the effects of hashish on patients and had published separate papers on the subject. Moreau was interested in using hashish to cure patients by evoking artificial psychoses while Aubert Roche wanted to use hashish to fight outbreaks of pestilence. The work of Aubert Roche has been — rightly — forgotten, but Moreau’s book contains striking insights into modern pharmacology. In 1845, Moreau argues in his book “Du hachisch et de l’alienation mentale (Hashish and Mental Illness)” that mental diseases could be studied by evoking abnormal states of mind in healthy persons by means of hallucination-inducing drugs such as hashish.

He assumed that hallucinations are a result of stimulation of parts of the brain where imagination and memories are located. Moreau carried out the drug experiments on himself and some of his patients. He also tried to convince his colleagues in the hospital to use hashish, but they refused. He found a more positive response from the bohemian artists in Paris, which is how the gatherings of the Hashish Club began.

The meetings, made famous in articles published by Gautier, were attended by many writers and artists of the day including Baudelaire, Honoré de Balzac, Alexander Dumas, Victor Hugo, Gérard de Nerval, and the painters Eugène Delacroix and Honoré Daumier. In one article, Gautier wrote that as he felt himself go under the influence of hashish, he noticed a strong urge to draw, and within five minutes, he had put down over fifteen sketches on paper. One sketch depicted Moreau in Turkish costume, seated at the piano. Gautier represented the synesthetic colors of the piano notes as curly lines above the instrument. After consuming “dawamesque” — a green pasta of hashish, butter, pistachio nuts, almonds, and honey — Gautier reported his perceptions in time units as in a scientific report.

At the beginning of the experience, Gautier was seized by a general freezing sensation and his body felt as though it had become transparent; he felt his eyelashes grew and curled up as gold threads on little ivory wheels. Around him, color avalanches glittered as in a kaleidoscope. Half an hour later, he got into a second hashish flush with even stranger visions of billions of swarming butterflies whose wings made an intensely loud noise as if they were fans. Gautier finally described how his hyperesthesia produced synesthesia-like perceptions:

“Giant crystal flower calices, enormous rose-mallows, golden and silver lilies mounted and opened around me with a crackling like bouquets of fire works. My hearing was developed extraordinarily; I heard the noise of colors. Green, red, blue, yellow sounds reached me in perfectly distinguishable waves.”

Following the lead of Dr. Moreau, Gautier considered these drug-induced synesthetic experiences to be experiences of artificial psychosis. He described it as the frightening experience of the alienation of his own body (which is, in fact, very different from how synesthetes describe their experiences nowadays). Contrary to Baudelaire, who considered sensory correspondences to be revelations of spiritual correspondences, Gautier plainly considered it a disruption in the brain.

As we have seen, the revelation of sensory correspondences by drug use was a subject of 19th-century literature. Some writers took it seriously, but others treated it as fun or a snobbish bijou. From two of the more serious thinkers, however, two opposing views emerged on drug-induced sensory correspondences. The first view, exemplified by Baudelaire, was that correspondences were perceived in a state of hyperesthesia, a hypersensitive state revealing a spiritual unity of the senses. A second view, voiced by Gautier and Dr. Moreau, was that the drug-induced perception of correspondences was a hallucination resembling the hallucinations caused by a mental disorder. Who is right, according to the ideas of contemporary scientists? Can contemporary scientists perhaps offer a third view on the relationship of drug use and synesthetic perception?

During the 1950s and 1960s, there was much experimentation with LSD (lysergic acid diethylamide). Some people reported side effects that sounded like synesthesia when they described their color perceptions. For example, some individuals reported that the LSD added color percepts to nonvisual stimuli such as pure tones. These reports were very similar to the descriptions of hyperesthesia and color hearing reported by Baudelaire and Gautier.

In the 1960s, a pharmacologist named Leo Hollister found that after subjects were given LSD, the addition of pure musical tone to the presentation of a visual flicker altered the color and patterns of the perceived flicker. Later in the 1980s, the British neurologist Peter McKellar observed that a subject who had been given mescaline responded to tactile stimulation by a sharp object by saying; “I’ve got concentric circles like around the top of a radio mast. If you touch me, jagged things shoot up; little sort of jagged things, from the center.”

At the same time, the British perception researcher Richard Gregory subjected himself to an injection with ketamine, an anesthetic drug that was often used in plastic surgery, and reported his perceptions to his fellow-researchers. When they caressed the palm of his hand with a hairbrush, Gregory had “a sensation of red wool, woven in squares, like a tapestry,” and when he moved his finger across the bristles he perceived “purple, red images, clear like hypnologic images that were highly saturated like Turkish tiles, orange and green and red.” When a comb was swapped for the brush on his hand, he got “vivid green and red sensations as the comb moves.”

These studies showed that hallucinogenic drugs led to a higher sensibility for physical stimuli, resulting in co-perceptions such as moving colors and forms. They confirm Gautier’s view that drugs can evoke synesthetic perceptions that are hallucinatory. The participants in these studies were not synesthetes. What happens when a synesthete takes hallucinogenic drugs?

After decades of incidental reports of synesthesia as a side effect of drug-induced hallucinations, drug-induced synesthesia started to become studied more systematically in the 1980s. One of the pioneers in this field is a Washington, D.C.-based neurologist, Richard Cytowic. In his popular book, “The Man Who Tasted Shapes,” he describes the case of his patient Michael Watson, for whom a minty taste in his mouth evokes a tactile sensation that is as cool and fresh as the curve of a glass column in his hand. For Watson, flavors have shape. While he tastes the flavors in his mouth, he also feels the shapes all over his body, but mainly as sensations of objects rubbing against his face or in his hands.

Watson tells Cytowic that his synesthetic perceptions vary in intensity during the day. On mornings after some serious drinking, he hardly feels the flavors in his hands or elsewhere on his body. The neurologist learns that Michael drinks many cups of coffee in the morning to sober up and get over the hangover. Could the use of depressants such as alcohol and stimulants such as coffee affect synesthetic perceptions? Watson participates in an experiment by Cytowic with “socially accepted” drugs — alcohol and coffee. After the intake of alcohol, a taste of spearmint increases the sensation of glass columns in his hands, while after coffee, all that is left is the tactile sensation of some small columns further away.

According to Cytowic, stimulants, like coffee, stimulate the higher cognitive functions in the neocortex (the relatively thin multifold outside layer of the brain), whereas depressants, like alcohol, suppress the responses of the neocortex. Suppression of the rational cortical area lets activity of the emotional limbic system (more centrally located in the brain) emerge and pushes it into the foreground of experience. Cytowic locates the source of synesthetic processes in this limbic system, and thus his predictions that coffee will block and alcohol will enhance synesthetic perceptions were confirmed.

In Cytowic’s studies, unlike in the experiments discussed earlier, synesthesia is not a temporary hallucination. Watson’s synesthesia is permanent and can be slightly modified by taking drugs. Later studies into drug-induced hallucinations of nonsynesthetes confirm Gautier’s reports, but the only study into the modification of synesthetic perception in a synesthete matches Baudelaire’s view. In fact, drug-induced hallucinations and drug-modified synesthesia are two different phenomena.

So the question remains: Is there a direct relationship between synesthesia and drug-induced hallucinations? Though some overlap can be observed in both types of perception, I don’t believe there is.

First, drug-induced hallucinations are temporary, lasting only as long as the drug lasts, whereas synesthetic perceptions are always there throughout one’s life. Second, the perceptions of sensory correspondences change in drug-induced hallucinations, whereas in synesthetic perceptions they are consistent. Third, drug users can distinguish hallucinations they have while under the influence of drugs from their normal states of mind, whereas synesthetes perceive their sensory correspondences while in a normal state of mind. In fact, no observations by others indicate that synesthetes show hallucinatory behavior. Fourth, whereas drug-induced hallucinations are often disruptive to a person’s normal functioning, the “visions” seen by synesthetes don’t interfere with normal life, and in some cases, they help the synesthete perform better, for example, in cases where synesthetes use colors to do mental arithmetic. And lastly, many synesthetes report that they first discover their synesthesia during childhood and not during their first drug experience.

Once dismissed as imagination or delusion, metaphor or drug-induced hallucination, the experience of synesthesia has now been well documented by scans of synesthetes’ brains that show “crosstalk” between areas of the brain that do not normally communicate. What makes it such a fascinating phenomenon is that it raises questions that still perplex scientists. Synesthesia is not an isolated phenomenon in human perception. It is not a fantasy, nor can it be marginalized as an unimportant by-product of a human brain process gone awry. The numerous synesthetes I spoke with when writing my book “The Hidden Sense” regard it as essential in their lives. While reproducing the true experience of synesthesia may be impossible, reorganizing our concept of the sensory channels of the mind is a worthy objective. It can change our view of the human mind, after all, and possibly of the physical world.

Exploring Drug-Induced Synesthesia. By Crétien van Campen. The MIT Press Reader, September 9, 2019.

Crétien van Campen is a Dutch author, editor and scientific researcher in social science and fine arts. He is the author of several books, including “The Hidden Sense: Synesthesia in Art and Science,” from which this article is adapted.

The MIT Press

Oh, to be a synesthete, those rare people with access to an extra layer of perception. Sounds have colors. Words have taste. Colors play music. The list goes on. The phenomenon isn’t totally understood by scientists, but the general idea is that those with synesthesia experience sensory inputs differently than the rest of us.

It’s no wonder that synesthesia is common among artists. But for those of us that just see letters as letters and can’t taste a song, synesthesia is more apt to inspire jealousy than creativity. We simply don’t have the neural link-ups that lead to the ability.

Not so fast, say two researchers from the University of Michigan. In experiments with normal (i.e. non-synesthete) people, Anupama Nair and David Brang say they induced a specific kind of synesthesia with a simple technique. When participants were played sounds in a dark room, around half of them experienced flashes of light, though no actual light was present. It means that synesthesia may be more common that we thought — most of us might simply not encounter the kind of situations that stimulate it.

The research, published this month in the journal Consciousness and Cognition, was inspired by a puzzling experience Brang had as a graduate student.

“While waiting to fall asleep at night with my eyes closed in a dark room, sudden and unexpected sounds (such as the house creaking or a door slamming) would cause a brief but salient flash of light (white or colored, and either encompassing my entire visual field or taking on a complex pattern),” he says in an email.

“Surveying undergraduates, I quickly found that the sensation was quite common while individuals waited to fall asleep at night.”

This is similar to sound-color synesthesia, where sounds will be associated with different, specific images.

Brang, now an assistant professor of psychology at Michigan, teamed up with Nair, and they set out to recreate the experience in the lab. They recruited 21 undergraduates from the university and had them sit in a dark room for five minutes with their eyes closed. A recorded voice then read letters of the alphabet, preceded by a visual attribute like “curved” or “symmetrical.” The participants had to say if the letter possessed the characteristic stated.

After some of these letters, the researchers would play a short beep, and the participants had to press a button if they had seen anything unexpected. Surprisingly, it was fairly common, they found. About 50 percent of the people reported seeing flashes of light in a few different patterns after hearing the beep, though nothing was actually there. Further experiments found that louder beeps would cause the flashes more often and that they were more common if the beep immediately followed the cue to imagine a letter.

In short, the researchers seemed to have activated some sort of latent synesthetic capability in their participants. It shouldn’t actually be so surprising, they say. The areas of our minds that are responsible for compiling and translating various sensory stimuli, like sounds and colors, are actually interconnected in all of us, Brang says.

This helps us understand when someone is talking, for example: we’ll pick up on the sight of someone’s mouth moving, and that helps cue our auditory system to pick out words. These kinds of connections don’t normally create noticeable stimuli, rather, the sight of a mouth moving simply helps jog auditory neurons into action. In the right conditions, though, these interconnections can produce things we’ll actually experience.

“We used a couple of ‘tricks’ to shift the balance of this auditory-visual connection,” Brang says. The researchers damped down the visual input by putting the subjects in a dark room while simultaneously stimulating their visual cortex by asking them to imagine pictures and they used loud sounds that would evoke a strong signal along the auditory-visual pathway.

We all might be potential synesthetes, in other words. Those of us who experience the cross-sensory stimulation in everyday situations might simply have stronger networks of interconnection, allowing the experience to happen more easily. Other studies have shown that people can be trained to associate different letters with colors, and documented the appearance of synesthesia in those with vision loss. There’s also, of course, the experiences of those taking psychedelic drugs like LSD, long known to induce synesthesia. It’s still unknown whether that form of synesthesia occurs in the same way as the non-tripping kind, though.

As for why some participants in the study were still resistant to synesthesia, Brang thinks they might simply not have been stimulated enough or in the right way.

“My hunch is that this is a trait-like difference, such that those who experienced these sensations are more susceptible to them,” he says. “Two possibilities are that this is due to greater visual-cortical excitability in some individuals (since more excitable neurons would fire more easily to the auditory inputs) or a stronger auditory-visual anatomical connection. It should be possible to evoke these sensations in most individuals but it may just take a more tailored context.”

When you’re falling asleep tonight, maybe take a moment and listen — you might get a flash of inspiration.

We Might All Have Synesthesia, New Study Suggests. By  Nathaniel Scharping. Discover Magazine,  April 18, 2019

For most people, a bad toothache feels like a persistent throb or a sharp pain. But without a dentist visit, there’s no way to tell whether it warrants a root canal. A synesthete, however, might wake up one morning and see the tooth glowing orange. For Manhattan-based artist and co-founder of the American Synesthesia Association Carol Steen, physical discomfort manifests as color (usually, a bright chrome orange). And in Steen’s case, much to her dentist’s surprise, she was able to diagnose a dying nerve before any clinical signs of tooth damage.

The word synesthesia means “union of the senses,” and synesthetes — roughly 4 percent of the population — are adults whose senses mingle in a sort of cross-wiring of the brain. Based on self-reporting and scientific case studies so far, there appear to be 80 varieties of these involuntary sensory perceptions. Shapes and sounds can have particular tastes, while letters or numbers can embody distinct personalities and genders. To take examples based on scientific literature, for one synesthete, the sound of a high C on a trumpet induces a flash of Ferrari red. For another, eating chocolate-covered raisins causes a sensation in the fingertips. For a synesthete with “ordinal-linguistic personification,” the number 9 might be a bearded hipster, while someone else swears 9 is a high-ponytailed blonde. It’s that idiosyncratic. Greta Berman, a Juilliard art historian who studies synesthetic artists, explains synesthetes don’t just think 9 is this or that. They know it is, and they will “fight to the end” that a number has a certain persona or is a specific shade. For Steen, five is cadmium yellow medium. Though her father, also an artist, insisted five was yellow ochre. And like most with synesthesia, Steen can’t recall “5” ever being a different hue or not having joined senses.

These days, so many celebrities seem to be proclaiming their synesthesia, it feels, as best-selling novelist and radio host Kurt Andersen references in one of his Studio 360 podcasts, like a kind of neurological “humblebrag.” Kanye has it. So does Beyoncé. And Lady Gaga’s got it, too.

In fact, a growing body of evidence shows synesthesia is more common among creative types and that some of the most imaginative minds — Hockney, Kandinsky, Nabokov — were indeed synesthetic. According to those who study the condition, cross-sensory experiences may offer a particular artistic advantage: a greater aesthetic sensitivity than the rest of us, and thus a greater likelihood to gravitate toward artistic fields. After all, synesthetes are able to express seemingly unrelated concepts in a variety of mediums: numbers with personalities, colors with pain, moving shapes with sound. And unlike their colleagues, synesthetic artists — those who use their neurological trait as a foundation of their practice — respond intuitively to what Steen calls the “multimedia-like stimuli” going on around them. An “ordinary” painter either captures a landscape before her or something she imagines. A synesthetic one paints what she actually visualizes when hearing a specific concerto — or as Steen explained, what she sees when she feels the jab of a tetanus shot.

“There are times when the vision I have is great and I can’t wait to run home to paint what I’ve seen,” said Steen, who is known for incorporating her synesthesia in her art. Her abstract painting Full View is what she perceived when her acupuncturist removed the needles at the end of a session. Still, not everything she experiences is “synesthetically wonderful.” “I assure you that if I smell something really bad,” she explained, “it’s not anything anyone would want to see.” Steen describes the reaction as an immediate physical response. In fact, she listens to music when she goes to the art-supply store, carefully removing the paint-tube cap to see if the color matches the sound she’s hearing.

But until fairly recently, synesthesia had its share of skeptics. In 1980, according to George Washington University neurologist Dr. Richard Cytowic, synesthetes were still often dismissed as “looking for attention” or just “speaking metaphorically,” such as “bitter cold” or “loud tie.” In his book, Wednesday Is Indigo Blue: Discovering the Brain of Synesthesia, Cytowic recalls how colleagues joked about his research subject, Michael, who “claimed” he felt intense flavors running down his arm. According to them, Michael was either “crazy” or “on drugs.” Synesthesia couldn’t be real, because it contradicted the dominant scientific paradigm that senses travel along five separate channels.

Since then, the science of synesthesia has come a long way, thanks to neuroimaging and the ability to connect somebody’s sense of the reality of the world to her brain’s architecture. A person no longer has to “claim” that Wednesday is indigo blue; researchers can compare activity between her cortical areas when she sees the word to a non-synesthete’s brain scan. To take a handful of studies, there’s now a known genetic link in families, as well as a neurological basis for the most common form of synesthesia, “grapheme-color,” when numbers and letters have distinct colors. A 2013 paper in Cerebral Cortex also identified a neural link between feeling and hearing, showing that in rare instances, synesthesia can also be acquired after a stroke. Using MRI, neuroscientists found that, indeed, the body can “mix up” sound and touch even without brain damage.

“We all have a little bit of synesthesia,” said Tony Ro, CUNY Graduate Center professor of psychology and the article’s lead author. Nails on a chalkboard make us cringe; a buzzing mosquito makes us itch. But today, Ro explained, scientists understand the anatomical basis for the seemingly random reactions, and how synesthetes have greater neural crosstalk than the rest of us. Still, for most people, it’s nearly impossible to grasp what intertwined senses are like; how it feels to live with chromesthesia — the “sound-to-color” that Steen has — or her experience of “colored pain.” But at least artists like Steen provide some visual equivalence for non-synesthetes. Steen works in three dimensions, too. Her twisted bronze and steel blue sculpture, Cyto, conveys the shapes and color of the first two syllables of Dr. Cytowic’s name. Even today, the synesthesia community feels tight-knit. In 1993, after hearing Dr. Cytowic on the radio, Steen reached out to discuss her synesthesia, which she’d kept hidden for decades. They soon became friend-colleagues, and she gifted him Cyto as thanks for giving her “knowledge” and “freedom.”

Photographer Marcia Smilack is also known for using synesthesia as a cornerstone of her process. As a “reflectionist” — her term of art — Smilack takes trippy pictures of the ocean’s surface the moment she has a synesthetic reaction, some of which have a Screamesque quality to them. And Smilack appreciates the comparison, feeling an uncanny connection to Edvard Munch, and the “sound waves” she sees in his famous, distorted images. (Incidentally, Berman thinks Munch might’ve been a synesthete too.) “I think of my work as painting by camera,” Smilack explained. “The colors I see are more like colored light than paint pigment.” For example, Cello Music illustrates Smilack’s auditory perceptions of reflections one night, off moving water. “I aimed my camera at the source and clicked the shutter the moment I felt satin against my skin,” she said.

At the same time, synesthesia can lead artists awry. Sean Day is a musician who sees shapes, movements, and colors when he hears timbres. For 20 years, he’s operated the Synesthesia List, an online forum, regularly cited by synesthesia experts and scientists. Day started scoring music in his early teens, composing by the colors he wanted to view and finding inspiration in fellow-synesthete Duke Ellington. In college, however, Day realized his synesthesia was actually hurting his creativity. “I focused way too much on my synesthetic colors,” he wrote in an essay for Oxford’s Handbook of Synesthesia. “I was ignoring what I was learning about balancing orchestration,” Day explained, “and my music sometimes was ludicrous, like mandolins and bagpipes.”

So, by his mid-30s, when writing music, Day started either ignoring his synesthesia completely or, if the piece called for a solo, focusing only on that one color or texture, without trying to combine instruments. Synesthesia does not make you a better artist, he said (emphatically and multiple times). Synesthetes are just as likely to be “crappy untalented musicians” as anybody else. Excellence in any art form comes from talent, practice, and mastery — not from having different sensations as most people. But, he clarified, if music makes you see colors and shapes, you might be more likely to pick up a guitar or sit at a piano in the first place — since music feels so multilayered.

A survey of 358 fine-arts students at three large universities, published by the Creativity Research Journal in 1989, suggests synesthetes are more common on artistic turf. Twenty-three percent of respondents experienced synesthesia in a “spontaneous and consistent mater”— over five times expected in the general population. The study also found that synesthetes scored significantly higher on four standardized creativity measures. For example, they had a mean score of 38.4 (40 being the creative gold standard, 20 the norm) on the Barron Welsh Art Scale, which asks respondents to “like” or “dislike” 86 designs, specially selected to distinguish between the typical judgments of artists and nonartists. As Dr. Cytowic describes, synesthetes see the similar in the dissimilar (music and color; pain and color; syllables and shapes), and people who excel at making metaphors are generally more creative. “But far greater in number than famous artists who happen to be synesthetic, “ he said, “are ordinary synesthetes who happen to be skilled in literary arts, paintings, or playing a musical instrument.”

And creativity has many guises. Marcos Lutyens is a cutting-edge artist who stages “perceptual interventions” at museums like Paris’s Centre Pompidou and the Los Angeles County Museum of Art. He uses hypnosis and performance to challenge the way viewers respond to stimuli, and has worked with synesthetes, especially, to examine how they perceive reality. In San Francisco, Lutyens sent a group of individuals with synesthesia to McDonald’s — the most ubiquitous American place he could imagine. One participant, who experiences words as color, said the Golden Arches symbol is “wrong” because it should be “red.” For another, the kitchen equipment sounds “shuddered [her] neck and back in a softer, indescribable kind of shock.” “What we classify as artistic,” Lutyens said, “is just normal to them.” And artists with synesthesia work outside of traditional venues, too. For instance, Lutyens describes how an award-winning mixologoist, a synesthete based in Manchester, England, Jody Monteith, mixes the color of drink flavors to “tap into the perfect taste.”

“Do synesthetic artists have a common way of seeing even when they aren’t consciously using synesthesia in their process?” asked Greta Berman, who co-curated (with Steen) the 2008 exhibit, Synesthesia: Art and the Mind, at the McMaster Museum of Art in Hamilton, Ontario. According to the show’s catalogue, she (and Steen) brought four recognized, “genuine” synesthetes together for the first time: David Hockney, Joan Mitchell, Marcia Smilack, and Carol Steen. Based on personal writing and his oeuvre, Berman suspects van Gogh was a synesthete too.

“Here’s the difference,” Berman said. “I don’t think Monet had synesthesia. He’s trying to reflect a physical scene, looking directly at a landscape, and not a sensory vision he had.” As an indication of synesthesia, Berman often searches artwork for “Kluver’s form constants”— geometric patterns (often lattice or spider-web-like), discovered by psychologist Heinrich Kluver in the 1920s, which regularly appeared during peyote hallucinations and synesthetic perception. “Anyone looking at paintings by van Gogh, Charles Burchfield, Wassily Kandinsky, and David Hockney, for example, will surely observe these form constants repeatedly,” according to Berman and Steen’s essay in Oxford’s Handbook on Synesthesia.

Yet the true power of synesthetic art may lie in what the 96 percent of us who are non-synesthetes can gain from it. “Synesthesia shows you how different sensory perception can be for everyone,” said Day. He calls it a lesson in “neural diversity” and that synesthetic art “strives towards a new understanding” of what’s “normal” for the human brain. Normal, he explains, is diverse. On the humanist side, Dr. Cytowic said in an email, synesthetic studies affirm subjective points of view: how two people can see the same “objective” thing quite differently — each equally valid — in a time “when citizens are becoming increasingly polarized.“

Most of us will never hear colors or taste shapes. But it is pretty common for a non-synesthete to get chills during an operatic crescendo or the high notes of the “Star-Spangled Banner,” or standing in the Sistine Chapel. These are dual-sensory experiences — auditory, visual, and physical stimulation — but more importantly, a way of deeply inhabiting a moment in time and the world more richly, which is, in the end, what it means to have a genuine connection to art.

Why Do So Many Artists Have Synesthesia? By Jacoba Urist. The Cut, July 7, 2016.