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Seeing Sounds and Hearing Colors: A Theory on Synesthesia

My first exposure to the phenomenon of synesthesia was in high school; I was hanging out with my friends after school and one of Kanye’s old albums was blasting in the car.

One of my friend then proceeded to make an offhanded comment about how he wished he could “see” the song we were listening to, not see a live performance per se but “see” the notes and rhythms in the music. I first dismissed it as him just being a smartass– trying to make one of those profound statements that seem more thought provoking than they prove to be.

But what he had said was now all I could think about, and we soon found ourselves discussing about synesthesia and why only a small subset of people have it.

Originally discovered by Francis Galton, a cousin of Charles Darwin, in the 19th century, synesthesia is a particular phenomenon that exists in only a small subset of the population. These individuals, who are normal in every other sense, experience the following: every time they see a number, they see a color (even if the it’s black ink on white paper), or every time they listen to music, it evokes a color. For example, the number 5 can represented as red, 9 as yellow, and 3 as green. In another form of synesthesia, A# can be a deep blue while C can represent a dusky pink.

There are several different kinds of synesthesia, but it all comes down to experiencing sensory information in a form that’s different from its organic form. That is why those with synesthesia can “see” sounds and “hear” colors.

Before we get into a theory about the neurological basis of synesthesia, there are two important facts you need to know about the condition.

  1. Synesthesia runs in the family. There is a genetic component to it.
  2. Synesthesia is eight times more common amongst those in the creative industry: poets, musicians, artists, writers, etc..

Are these two observations mere coincidences? I think not. So how can we explain this?

Well, according to a TED talk by Dr. V.S. Ramachandran from the University of California, San Diego, the part of the brain that represents the color area and the number area are adjacent to each other in the fusiform gyrus. Due to the spatial proximity of the two regions, there is a cross wiring that occurs which explains why numbers result in colors, even if they are written in black ink on a white piece of paper.

Given what we know about the hereditary nature of synesthesia, Dr. Ramachandran hypothesizes that there must be an abnormal gene that results in this type of cross wiring.

Babies, as it turns out, are born with everything wired to everything else. As they grow older and mature, they undergo what is called synaptic pruning: the connections between neurons (synapses) are trimmed down to more defined networks based on what they learn and what they experience. There is even speculation that all babies might have synesthesia but as you can probably see, it is very hard to test this experimentally.

Therefore, there is a gene that is responsible for this synaptic pruning, and any mutation in that gene that results in cross wiring is also passed down to the next generation of offspring.

Depending on what is exactly cross wired, you get different kinds of synesthesia. If it’s between tone and color, you get tone-color synesthesia, and if it’s between number and color, you get number-color synesthesia.

Writers, artists, musicians– they all have a heightened ability for metaphorical thinking. Regardless of the medium one chooses to express his/her thoughts in, creativity arises from the language of metaphors, the ability to draw comparisons from two seemingly unrelated things.

According to Dr. Ramachandran, cross wiring in the brain, if extended to regions beyond the fusiform gyrus, enables a greater propensity for creative thinking in people with synesthesia, thus explaining why synesthesia is eight times more common for people in creative professions.

Ramachandran insists, however, that we are all synesthetes to some extent.

Imagine that the two figures above are characters of the Martian alphabet. One of them is called “Bouba” and one of them is called “Kiki.”

Take a guess. Which one is Bouba and which one is Kiki?

Most people would say that the left is Kiki while the right is Bouba. Why is this the case? We are all engaging in what is called cross-modal synesthetic abstraction. The sharp, harsh, consonant-heavy inflection of “Ki-ki” in our auditory cortex is associated with jagged shapes more strongly than the rounded figure of the adjacent shape. Similarly, the rounding of our lips required to elicit the sound “Bouba” is associated with round shapes and structures.

It seem a little silly; in fact, it is rather silly, but it makes a point. Our brains are able to engage in a primitive form of synesthetic abstraction and connect our sensory pathways. A more complex version of this in the fusiform gyrus and we have ourselves the full blown phenomenon of synesthesia.

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