By Melody Xu
Art by Alex Hanson
When people hear the term synesthesia, the image of an individual who sees the number “3” in maroon or thinks that “purple” tastes salty usually appears. However, the term serves as a term for sensation interconnections that are even more complicated— violin music will lightly stroke against a person’s cheeks, the days of the week are carts on a ferris wheel. So what exactly is synesthesia?
Synesthesia, as explained by the Oxford Dictionary, is “the production of a sense impression relating to one’s sense or part of the body by stimulation of another sense or part of the body”. Deriving from the Greek term “to perceive together”, the phenomenon of synesthesia can come in many different shapes and sizes; some may be able to smell pain, others may taste shapes, some might be able to do both and even more. While there are countless types of synesthesia, without any two cases being exactly the same, there are some common types of synesthesia that occur within the human population, especially grapheme-color synesthesia, which is when a person may see individual letters and numbers in different colors.
Synesthesia, like many other puzzles, should always be examined through an interdisciplinary lens. For instance, synesthesia can also be seen as a gateway for creativity. When a novel’s narrator says that they see the rainbow when they hear the deep, soothing voice of their favorite singer, or when a painting’s harsh oil strokes clearly evoke a feeling of anger— these are all examples of creativity at its finest. Taking a deeper look reveals that these are connecting experiences primarily focused on one sense with another sense, which certainly can be considered an attempt to replicate the experiences that come with synesthesia. Whether the platform for examining synesthesia comes in the form of literature, music, art, or neuroscience, it’s an experience that has been the focus of human intrigue for all of history.
For scientists especially, synesthesia presents an interesting issue. Studies have been conducted that confirm that the phenomenon is in fact biological, happening automatically and without having any learning process behind it. It is neurologically distinct from hallucinations and is unlike metaphors, but the estimation for how many people have synesthesia (from 1 in 200 people to 1 in 20,000) and the causes of synesthesia has been a prevalent problem in the scientific community. The issue of the huge disparity between the estimation of people with synesthesia in the population is so prevalent in part because of the fear of judgement that people who have synesthesia have. The fact that the term itself is a blanket term for so many different variations of the phenomenon also has an impact on the wide range of values.
Modern technology and tools, including brain-imaging and molecular genetics tools, have allowed to scientists to look at the future of examining this phenomenon, along with the organization of the brain and the way we perceive and recognize the world around us, with promise. However, this was not always the case. Long having been dismissed of having neurological basis, synesthesia had been misunderstood by people for a large part of human history. In the late nineteenth and early twentieth century, the world was swept up in a flurry of excitement over examining this phenomenon, but it also experienced a harsh dip in interest in the middle of the twentieth century. One of the incredible scientists responsible for the establishment of synesthesia as a major research area was Simon Baron-Cohen, a prominent psychologist and cognitive neuroscientist. In the 1970s he led a team who first found evidence that synesthetes have consistent experiences over periods of time, as well as established a method of measuring synesthesia through neuroimaging techniques. (Here is some info on Baron-Cohen’s book on the project.)
Despite all of these major steps forward in synesthesia research, the actual cause for synesthesia remains shrouded in mystery. Some theories claim that all newborns are born with synesthesia, with the division of sensory blocks appearing as the individual and brain mature. Other theories involve the opening of previously closed channels of communication after being exposed to “the light of consciousness,” hence why people who are under the influence of certain drugs and have these passageways coming into awareness can experience a sense of induced synesthesia. Regardless of what theory you choose to believe in, the study of synesthesia allows cognitive scientists a truly unique chance to learn about how perception is formed in our brains.