By Ava Nagy
When I was a kid, I had a violin instructor who could see sheet music come to life. To my astonishment, I had known her for three years before this information came up in conversation. I had been sitting in the eclectic, circular “music room,” in the back of her home, complaining about how difficult it was for me to sightread a piece of music for the first time. I remember I had asked her how she did it so easily, expecting to be met with one of her usual sayings – “practice makes perfect,” or one of its many variations – but this time she only smiled.
“Each note is a different color,” she explained. C sharp, for example, was dark brown, whereas C flat was bright pink. They were unmistakeable; a slight change in position on the page represented a leap of hue that made their finger placements obvious. As she played, she witnessed a progression of color swelling from the page, creating a unique pattern to which she could return easily the next time she sat down to practice.
This is because my instructor had a type of synesthesia known as Chromesthesia, correlating colors to sounds. However, this is only one of many possible associations. Other variations of synesthesia correlate different combinations of colors, numbers, motion, shapes, sounds, sensations, motion, and even time.
In one particularly fascinating case, author Daniel Tammet describes his combination of multiple types of synesthesia: “The number 1… is a brilliant and bright white, like someone shining a flashlight into my eyes. Five is a clap of thunder or the sound of waves crashing against rocks. Thirty-seven is lumpy like porridge, while 89 reminds me of falling snow” (Tammet, 2007).
These associations can be either distracting or helpful. Some synesthetes report a spatial understanding of mathematics that can reveal hidden relationships between numbers, as each one occupies a mental location in space. Interestingly, Einstein was known to describe his mathematical thinking as “spatial in nature,” suggesting he might have experienced the condition himself (Brang & Ramachandran, 2011).
So, what is the neurological basis for these experiences? While scientists don’t understand the exact cause of the condition, recent studies have revealed possible explanations. For many years, it was believed that a crossover between the processing of different brain areas occurred in high level cognitive areas. However, recent studies show that visual forms of synesthesia are related to the processing area V4 of the visual cortex.
Another thing we’ve learned is that synesthesia is heritable. That is, 40% of synesthetes report a first-degree relative with the same condition (Brang & Ramachandran, 2011). However, there is no single gene that invokes its presence. One study identified 37 separate genes that could predict its development.
Certain drugs that invoke temporary synesthesia may be key to understanding the neurological underpinnings of the condition. According to one study, LSD elicits similar symptoms by activating serotonin receptors, suggesting that S2a receptors are involved. What’s more, the same study found two subjects who reported that Prozac inhibited preexisting synesthesia. Prozac is known to inhibit that same S2a receptor, adding to the evidence that it might produce symptoms of the condition. One subject even experienced grapheme-color synesthesia for the first time after taking 5mg of melatonin, which disappeared after the drug left his system. Interestingly, serotonin is metabolized into melatonin, which then results in the inhibition of serotonin production, leading to the activation of S2a receptors. (Brang & Ramachandran, 2008).
The conclusion of these cases, according to the publishers of this study, is that grapheme-color synesthesia is neurologically rooted in a crossover between the color area V4, and the “number area”, which are positioned next to each other in the fusiform gyrus.
All of these sensory experiences affect the way a person sees the world, both literally and figuratively. One study finds that synesthetes display greater openness to experience, convergent thinking, use of mental imagery, and verbal comprehension (Chun & Hupé, 2015). There are many possible conclusions to be drawn from these results. Perhaps the visualisation of verbal information allows them to store that information better than those without the condition.
However, it is important to remember that no two synesthetes experience the same mental experiences in response to the same environmental stimuli. Indeed, no two human beings can truly experience their environment in the same way internally. In this way, synesthesia serves as a great reminder of the vast range of internal human experience.
References
Brang, D., & Ramachandran, V. S. (2011). Survival of the Synesthesia Gene: Why Do People Hear Colors and Taste Words? PLoS Biology, 9(11), e1001205. https://doi.org/10.1371/journal.pbio.1001205
Brang, D., & Ramachandran, V. S. (2011). Survival of the synesthesia gene: Why do people hear colors and taste words? PLoS Biology, 9(11), e1001205. https://doi.org/10.1371/journal.pbio.1001205
Brang, D., & Ramachandran, V. (2008). Psychopharmacology of synesthesia; the role of serotonin S2a receptor activation. Medical Hypotheses, 70(4), 903–904. https://doi.org/10.1016/j.mehy.2007.09.007
Chun, C. A., & Hupé, J. (2015). Are synesthetes exceptional beyond their synesthetic associations? A systematic comparison of creativity, personality, cognition, and mental imagery in synesthetes and controls. British Journal of Psychology, 107(3), 397–418. https://doi.org/10.1111/bjop.12146
Tammet, D. (2007). Born on a blue Day: Inside the extraordinary mind of an autistic savant: a memoir.