What does it mean to hear music in colors, to taste voices, to see each letter of the alphabet as a different color? These uncommon sensory experiences are examples of synesthesia, when two or more senses cooperate in perception. Once dismissed as imagination or delusion, metaphor or drug-induced hallucination, the experience of synesthesia has now been documented by scans of synesthetes' brains that show "crosstalk" between areas of the brain that do not normally communicate. In The Hidden Sense, Cretien van Campen explores synesthesia from both artistic and scientific perspectives, looking at accounts of individual experiences, examples of synesthesia in visual art, music, and literature, and recent neurological research.
Van Campen reports that some studies define synesthesia as a brain impairment, a short circuit between two different areas. But synesthetes cannot imagine perceiving in any other way; many claim that synesthesia helps them in daily life. Van Campen investigates just what the function of synesthesia might be and what it might tell us about our own sensory perceptions. He examines the experiences of individual synesthetes—from Patrick, who sees music as images and finds the most beautiful ones spring from the music of Prince, to the schoolgirl Sylvia, who is surprised to learn that not everyone sees the alphabet in colors as she does. And he finds suggestions of synesthesia in the work of Scriabin, Van Gogh, Kandinsky, Nabokov, Poe, and Baudelaire.
What is synesthesia? It is not, van Campen concludes, an audiovisual performance, a literary technique, an artistic trend, or a metaphor. It is, perhaps, our hidden sense—a way to think visually; a key to our own sensitivity.
A very readable overview of the dominant strands of theoretical and empirical research regarding synesthesia. Not as much detail regarding synesthesia in art, perhaps because it's difficult to confirm whether artists who lived before common screening techniques actually had synesthesia or not. I felt the author rather missed the mark when it came to the question of whether hallucinogenic drugs create synesthesia (even if only temporarily) in the user. Also, in the latter half of the book, discussion of some recent studies seemed rather uncritical, which made me leery of accepting his conclusions in earlier chapters. Most frustrating for me was when the author wrote as if all synesthetes experience color in conjunction with another sense, especially since in his conclusion he notes that he didn't recognize his own synesthesia for a long time because "the media mention only a narrow range of the possible synesthesias. Most of the time, only colored letters and numbers are described." Some of my frustration at the imprecision of language is no doubt because I'd hoped for more insight into my own particular, tactile experiences. But, overall, a good overview that doesn't relegate the condition to dysfunction or aberration but presents it as a tool that can be cultivated and provide benefits.
“How does it feel to hear music in color, or to see someone’s name in color?”
***** I am a grapheme-color synesthete, which means I associate colors with words, especially people’s names. For me, each name has a corresponding color based on how it sounds, some names have a single color, while others have two or more. And certain names even have a distinct texture.
Growing up, I assumed everyone experienced the world in the same way, so I didn’t think much of it. I didn’t even know this phenomenon had a name—until just this month (October 2024).
I remember when I was in grade school, I told my classmate that her name was red and green with a rubber-like texture. She looked at me as if I was joking, and ever since then, I haven’t mentioned it to anyone again.
It never goes away though, and the color never changes. When I think about my classmate’s name from grade school, I still see the same colors—red and green with the same texture.
For example, I see my name “Veronica” as a deep maroon color with ridges and metal-like textures. Despite the fact that maroon isn’t my favorite color, it just suits how my name sounds to me.
For others, this might sound weird or, at worst, pretentious, so I keep it to myself. Until, one day, I used AI and asked if it was normal for people’s names to have colors. Then it introduced me to “synesthesia.” Then, I began looking for a book about synesthesia.
***** Reading this book made me realize that I wasn’t weird at all for thinking the way I did, and I am not alone. Many people have the same neurological condition as mine, while others have even more complex and fascinating conditions, like seeing colors when they hear sounds or music, also known as chromesthesia.
So what exactly is synesthesia?
According to this book, synesthesia is a neurological condition that occurs when a stimulus in one sense modality immediately evokes a sensation in another sense modality. Literally, “synesthesia” means to perceive (esthesia) together (syn). It's like two of your senses are merging. In general, synesthetic perceptions are considered abnormal because they do not fit into the theory of separate sensory systems. This book also mentions many theories of synesthesia in terms of brain function in an attempt to explain this condition.
Synesthesia as Abnormal Brain Function
1. One common idea is that synesthetic perceptions result from a miswiring in the brain of synesthetes. This “miswiring theory” assumes that everyone’s brain is essentially designed the same way, and it is the miswiring that causes the synesthetic mixture of perceptions such as colored sounds and colored tastes.
2. Another theory is the “leakage theory,” which suggests that adjacent brain areas “leak” information to each other.
3. A third theory is the “wrong feedback theory,” based on the feedback that normally occurs on an unconscious level of perception. Through this wrong feedback, abstract products of reasoning such as letters and numbers can mix with perceptions of color on an unconscious level, producing conscious phenomena such as colored letters and numbers.
Synesthesia as Normal Brain Function
1. The “limbic system theory” states that synesthesia is a product of the limbic system. Unlike the neocortex, where the senses have their separate domains, in the limbic system, all sensory nerve pathways mingle, producing mixed perceptions. This means that synesthetic perceptions are normal products of some older parts of the brain.
2. The “neonatal-pruning theory” begins with neonate brain development. This theory states that in the brains of synesthetes, some nerve connections between sensory brain parts are not pruned, as they provide certain advantages in life, and they still produce intersensory, or synesthetic, perceptions in synesthetic adults.
3. The “brain-plasticity theory” relates to the “neonatal-pruning” thesis and is based on the idea of the brain's plasticity. Recent studies have shown that the organization of the human brain is not determined at birth but adapts its functional organization to its environment throughout a person’s life. In this view, synesthetic perceptions are products of an adaptation of the brain to the environment in which the person lives.
4. The “neural disinhibition theory” explains that all sensory brain parts are structurally connected in adults, but not all are activated. Intersensory transfer is normally inhibited because it does not serve a purpose in perception. However, some intersensory nerve connections are permanently disinhibited in synesthetes, producing synesthetic perceptions.
There are still many things to learn and discover about this condition. Researchers and neurologists are still trying to understand it due to various factors. One issue is the problem of funding for research. Accurate statistics are available for life-threatening diseases because researchers receive substantial funding to screen broadly for these diseases. Synesthesia, fortunately, is not a disease and is far from life-threatening.
*****
This book is easy to read and well-written. I love how the author explores both the artistic and scientific sides of this phenomenon, along with its philosophical background.
I would highly recommend this book to anyone who is a synesthete, knows one, or is simply curious about synesthesia. :)
“Synesthesia is not an isolated phenomenon in human perception. It is not a fantasy, nor can it be marginalized as an unimportant by-product of a human brain process gone awry.”
A complex, scholarly discussion of various aspects of synesthesia, both scientific and philosophical. Though it does read like someone's thesis, it's a well-written one, and rarely strays into convoluted language. The conclusion in the final chapter, that one can "train" synesthesia, I'm not really buying: it doesn't seem adequately supported by the rest of the book. (There's also a spate of typos here while the rest of the book is very clean, but that's a minor note.) This is a good expansion on the concepts of synesthesia for a reader who already has a bit of grounding in the topic.
Maybe 2.5. I've long been fascinated by synesthesia and have read a lot on the subject. I found this to be rather dry and it didn't really add much to my knowledge base.
This is the best book I've found on synesthesia, a cool and quirky neurological condition my husband has. It was interesting to learn about all the different forms of it, including the types my husband has (spatial number arrangement and color-letter perception). I liked how the author presented the material as she discovered it herself and how she would often say that when she didn't understand a certain type of synesthesia, she would go chat with people that had it. The book was a good mix of her more casual observations, her research agenda, and a "raw facts" presentation of different forms of the condition.
Well synesthesia is a pretty cool thing eh. I wish this book was better written, but the guy who wrote it is Dutch, so I ain't complaining. It's a pretty good overview, but not an in-depth description of theories and accounts of synesthesia. It's reads like this guy is just working out some questions in book form, which is cool, because it leads to some interesting places, but is not so cool if you are not interested in his thinking through process. Oliver Sacks does a better job at this kind of thing I guess. It is a good introduction to the subject matter. Brains are neat.