By Shreya Parjan

A bite of magenta, a whiff of chartreuse.

Sensory whirlwinds where numbers breathe colors and violin music brushes softly across the ankles.

Beyond mere poetic portrayals of commonplace occurrences, such transcendent, seemingly hallucinatory sensory experiences are all too real for individuals with synesthesia. From Ancient Greek syn, “together,” and aisthēsis, “sensation,” synesthesia is a phenomena where stimulus in one sensory category provokes experience or emotion in another, allowing individuals to hear colors, feel shapes, and taste sounds.

Although redolent of a drug-induced hallucination or even linked to insanity and instability, the condition is actually rooted in a myriad of scientific explanations, and impacts anywhere from 1 in 200 to 1 in 2,000 individuals.
Forms of Disorder


When synesthetes receive sensory information, known as inducers, they receive prompts allowing them to perceive the information through different senses. The resulting synesthetic perception is called concurrent. The chart below conveys the results of a study in the American Journal of Psychology that surveyed and compared the results of 63 synesthetes to identify the most common inducers prompting synesthetic perceptions.

The figure above shows the most common inducers of crossover sensations in synesthetes. (Source:

The researchers concluded that most synesthetes are prompted by words or digits before associating them with colors, smells, or even personalities. However, even things like punctuation marks could serve as inducers for synesthetes.

There are four predominant types of synesthesia. In Grapheme-Color synesthesia, individuals associate letters or numbers with specific colors. While most synesthetes relate different colors distinctly with different shapes, studies have shown some overlap in perceptions between individuals.

When the crash of cymbals allows individuals to see vivid colors, or the pitter-patter of raindrops takes the form of soft grays, it is known as Sound-to-Color synesthesia.

Personification aligns images or other sensory information with unique personalities, as 8 becomes a cross old woman who acts superior to all other numbers while 7 remains naive and humble.

Finally, in the rarest of all, Lexical-Gustatory Synesthesia, certain words or sounds evoke a myriad of tastes for synesthetes.

Entangled Information

A study by the French Institute of Health and Medical Research revealed the neurophysiology of synesthesia by examining a review of functional Magnetic Resonance Imaging (fMRI) results, and the contrast between the sensory processing of synesthete brains and that of their ‘normal’ counterparts. The following brain scan shows that the brains of synesthetes display activity in different regions of the brain when exposed to the same sensory information.


In the diagram above, increased activity is evidenced by lighter colors, and while the brain of the non-synesthete shows no activity in the region of the brain associated with processing color information, that of the synesthete does. 

Researchers at UC San Diego conducted a similar study into the cross-activation of brain regions in synesthetes. As shown above in blue, when control brains were exposed to numbers and letters, they only exhibited activity (red and orange) in the grapheme-selective area of the brain which deals with numbers and letters, or graphemes.

However, synesthetes not only showed activity in the grapheme-selective area of the brain, but also in the hV4 region, as shown in pink. The hV4 area handles color perception, and its activation along with that of the grapheme-selective area indicates a link between the two regions known as neural cross-over.

The researchers concluded that the differing forms of synesthesia and broad range of synesthetes impacted with the disorder are rooted in the different possibilities of neural cross-over. This cross-wiring in the brain allows sensory information from one inducer to mingle with contrasting sensory information to create synesthetic perceptions of sights, smells, tastes, etc. that the rest of us see in one dimension.
Faces to the Frenzy

In an era before proper understanding of synesthesia, synesthetes were seen as inherently disturbed and often alienated upon realizing that others do not experience things in the same transcendent manner that they found so normal. However, with increasing investigation into the possible genetic origins of synesthesia, or even how it can be self-taught and acquired as a kind of skill, it has gained a realness through actual people that humanize the ‘disorder’ with their stories and experiences.

Many of them do not even realize that their ability to experience common sensations in such a manner is anything out of the extraordinary. As one synesthete writes, “I grew up assuming everyone had this sensation, but after explaining it to a few people, I realized that it was unique. I feel a shooting pain from the heel of my foot up through the back of my thigh when I hear about or see something painful. I grew up assuming that this sensation is what people meant when they referred to a ‘sympathy pain.’”

Due to the almost mystical nature of synesthesia, the disorder has even inspired a literary device by the same name. Having recently read The Great Gatsby, MVHS literature students like junior Allison Niu experienced ‘synesthesia’ first hand through the work of author F. Scott Fitzgerald, who often uses the device to add a transcendent touch to the “yellow cocktail music” (Fitzgerald 44) and spilling laughter at Gatsby’s parties.

According to Niu, “I think it goes with a new way to perceive things when ‘proper’ words just aren’t enough to give whatever the author is describing the image or feeling they want their readers to get.”

Perhaps the abnormal is not something for us to criticize or evaluate under the close lense of a microscope, but rather something that hints at what we ourselves can’t experience, be it an unimaginable new closeness to the experiences and emotions of those around us, or simply the ability to see what Monday’s personality really is like.

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