Picture this: You’re wandering around the coolest science museum in Philadelphia, and its after hours. They’re closed to the general public, but you’re a VIP. You have a cocktail in your hand and you walk up to a table with a hundred little shot glasses of chocolate samples and two nerdy scientists behind it. The perky one with the glasses says, “Can you help us advance science by trying some of this chocolate?”. You balk at first, of course, but finally deign to participate in the experiment.
The scientist explains the task to you, promising to let you in on the reasoning behind it, but only after you have helped her. She tells you there are two different kinds of chocolate, and you have to taste each. Then you are to name them. It is at this precise moment that you will make what I call “scrunchy face”: that contorted facial expression that is a universal sign of confusion. She assures you that you can do this, but first you have to do the work. Taste the chocolate. So you put the morsels of fair-trade, organic, dairy and gluten-free chocolate in your mouth, one by one, until you have a good sense of their gustatory differences.
Now the hard part: what will you name these chocolates? To make it a bit easier, name options have been provided for you:
Which chocolate would you like to call kiki? Which chocolate would you like to call bouba? While these may sound like some odd questions, you are more than capable of assigning different sounding names to tastes. And once you’ve completed the task, you’re let in on the ruse: The chocolates are both dark chocolate, one 72% cacao and the other a biting 87%. You likely would call the 87% cacao chocolate kiki and the 72% cacao chocolate bouba. But why? Why has she asked you to do this? How is this science? Don’t get me wrong, people are usually more than pleased to help science in this fashion, but they want to know why the nerd behind the table seems so enthused by their participation.
I am that nerdy scientist, and every few months I get to hang out at the science museum after hours and demonstrate the phenomenon of “Synesthesia” to the interested VIPs. Synesthesia comes from the Greek words for “together” (syn) and “sensory” (aisthesis), and is the sharing of perceptual experiences between sensory processing systems. Simply put, it’s when a person experiences the stimulus of one sense as another. Shapes or letters having inherent colors, tastes having auditory pitches. It has gained some traction in popular media recently, drawing the attention of psychological scientists and non-academics alike.
All sensory information (except smell) is sent directly into the same cluster of brain cells, located deep within the brain. This collection of cells is an area that has been named the thalamus. This area is evolutionarily preserved; most other mammals have this region as well, and neuroscientists often refer to it as the “sensory relay station” of the brain. The primary responsibility of the thalamus is to route sensory information to the appropriate higher-levels of the brain that process our different senses. With a synesthetic experience, it is thought that there is a “crossing of wires” in the brain that lead one sensory experience to create a completely separate perceptual experience. And it turns out that most people have the ability to activate one sensory system (e.g. taste) and experience a perception in another (e.g. sound).
Why does the darker chocolate often gain the moniker kiki over bouba? Well, darker chocolate tastes more bitter, and English-speaking people tend to use the word “sharper” to describe it. As it happens, the name kiki is a much sharper sound than bouba. Try saying it aloud Don’t worry, I won’t make fun of you. Of course, it does sound bizarre to tell someone that tastes sound like things, or even vice versa. Ask any kindergartener and they will tell you, we taste food and hear sounds, not the other way around.
Synesthesia was once thought to be extremely rare, and has been called some pretty negative things, like a “disorder”, “problem”, or “condition”. It is not a diagnosable disorder as far as both medical or mental health communities are concerned, and no one with synesthesia should be thought of as disabled or handicapped. It rarely produces severe adverse consequences/symptoms, and may even be pleasant or advantageous at other times. Recent work suggests it is much more common than we think, and academics haven’t begun to scratch the surface in uncovering the different synesthetic experiences that people are likely to have. Often these experiences are
- not talked about because they are hard if not impossible to explain, or
- the person experiencing the shared sensations doesn’t realize it is an “atypical” experience and thus does not share it with others.
While my demonstration is fun, it is not the most characterized type of synesthesia. Instead, the most common form actually has a name: “grapheme-color synesthesia” In this scenario, people experience specific color-number or color-letter associations and is more often reported with respect to numbers. Someone may always see the number “7” as lime green, no matter the color of the text it has been presented in. And likewise, “1” is red, “2” is blue, etc. etc. The experience is always consistent for these people, and it is also adaptive. For example, allowing someone to see colors embedded in mathematical problems may make it easier to solve problems in novel ways. One way that scientists test for the presence of this type of Synesthesia is pictured below. The image on the left is shown to participants in the lab and they are asked to use a pen to mark all of the “7’s” they see in the image. It would take the average person no more than a minute to complete this task. However, someone with grapheme-color Synesthesia would require mere seconds to identify all of the “7’s”, perhaps with the black text appearing as the image on the right below.
So if you ever find yourself seeing colors when you read or perform mathematical calculations, or actually hear the individual components of an orchestra while exploring complex flavor profiles at a fancy restaurant, or even assigning personality characteristics to the feel of different fabrics, REJOYCE! You are one of the lucky ones, the gifted, the synesthetic. Your brain has been wired uniquely for you, and your experience is likely impacted for the better or at least in a inimitable manner.