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Colorful Sounds & Tasty Numbers: An Introduction to Synesthesia

By Yuan Cheng


  • Synesthesia has many differing branches, each with its own symptoms.

  • It is mostly a rare and hereditary condition.

  • It does not need to be treated


Synesthesia is a rare neurological condition that affects around 4% of the population and all age groups. Although it comes with many specific variations in terms of symptoms, its key trait is the cross-communication between two or more different senses where only one is needed. For example, some synesthetes (those afflicted with lifelong synesthesia) report seeing each sound with an individual color, whilst others report being able to taste the textures of numbers.


There are over 60 categories of synesthesia. Different types of synesthesia are also likely to coexist in a synesthete. Here are three more well-known types:


It is a type of synesthesia in which one associates numbers, words or letters with distinct colors in their mind’s eye, even if these letters or numbers are printed in monochrome. It affects around 1% of the population, and is the most common form of synesthesia.

Lexical gustatory:

It is a type of synesthesia that allows one to be able to “taste” words or sounds. It is relatively rare: less than 0.2% of the general population have it.


Synesthetes with sound-to-color synesthesia (also known as Chromesthesia) are able to visualize sound or music as particular colors. It is incredibly rare.



According to current research, synesthesia can be hereditary and passed down through the bloodline. Via surveying synesthetes, scientists found that around 40% of them have an immediate family member who also has synesthesia. The genes that control normal cortical development might play a part in causing synesthesia, though further research is being conducted on this subject. Through psychophysical tests and functional imaging, scientists discovered that grapheme regions and color area V4 are activated at the same time in grapheme-color synesthetes, which could potentially explain their symptoms.

It is hypothesized that the various types of synesthesia are caused by the same genes. The divergent expressions within each individual happen because these genes only cause them to have a higher likelihood for synesthesia, but don’t determine the specific type they’d have. Women, however, are more likely to have the condition than men, with a 6:1 female to male ratio amongst synesthetes.


Synesthesia can also be acquired later in life in some cases, though most synesthetes experience symptoms since early childhood. Having a head injury, being exposed to drugs, and posthypnotic suggestions can all cause excessive serotonin in the brain and result in the development of synesthesia, though the chances are very small.



Synesthesia doesn’t need to be treated. In fact, many who have it enjoy the intriguing perspectives they get to experience. In some cases, synesthesia also boosts spatial memory. Those who have synesthesia are also statistically more creative—there are more cases of synesthesia amongst artists, and synesthetes surveyed spent more time on creative projects. A direct correlation has not been found as of now, but synesthesia does not hinder daily life.

Fun Fact

Lorde, Duke Ellington, Pharrell Williams, as well as certain other celebrities have synesthesia.



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