Once upon a time I read a science fiction story where the hero was trapped by his enemies. But they didn’t want to kill him. They just wanted to make him helpless. So they scrambled his brain circuits.
When he woke up, he found he was blind. But not blind in the usual sense. Every ray of light, every signal from his eyes, came to him as sound. Sight had been converted into a raucous, incoherent blast of sounds. And every sound from the outside world penetrated his brain as part of a kaleidoscopic riot of ever-changing colors. All his senses had been cross-wired. Nothing was comprehensible. And every move he made, every effort to understand and control his world, merely brought another overwhelming cascade of sensations.
I remember trying to imagine what it would be like, having all my senses switched, but I had to give up. It was both too terrible and too confusing to even bring up some sort of picture of what it would be like. All I could think of was that one would quickly go mad in such a world. I remember, though, being genuinely glad that it was just a science fiction story. That no one would ever really have to go through that.
Reassuring idea. Except I was not exactly correct.
It turns out that, when we are born, we have far too many synapses. In effect, our developing brains are massively cross-wired. Parts of the brain that will specialize in vision, say, or hearing, are connected to the areas for taste and smell as well. Newborns apparently live in exactly the world of sensory chaos as the character in that old science fiction novel.
But in the first few months, as the baby’s brain specializes, something called synaptic pruning occurs. Those superfluous circuits start to disappear and the baby’s world begins to get some sort of cohesion. Pretty soon the baby’s eyes start to track objects and it learns to respond to sounds and its mother’s touch. In time, each sensory area of the brain will specialize, so that the vision center processes nothing but sight and the auditory region processes nothing but sound.
It is only natural that we assume that, since we all go through the same pruning process, everyone hears what we hear, smells what we smell, sees what we see, etc. But it is only an assumption. Does the color blue look the same to everyone? Does lasagna taste the same to you as it does to me? Does a musical note sound the same? Obviously, the vibrations in the air can be the same, but sound is something that happens in our brains. And our brains are very different.
The answer to those questions, as it turns out, is “No.” No, lasagna does not taste the same to everyone. Musical notes are heard differently by each of us. And the blue inside your head is probably not the same as mine. But since we agree that lasagna tastes good, music is nice to listen to and a blue sky is pretty, it doesn’t matter very much. More importantly, if I look at something and say it’s blue, you would look at it and call it blue, too. We might be having different internal experiences, but we would agree that each was caused by that thing we call “blue.” It is the specialization of our brains that allows us to share a common world. Whatever our subjective reality, our brains carefully segregate our sensory inputs. We share a commonality of what sound is, or taste, or sight.
Unless we have something called synesthesia.
There are some people who, when they hear a musical note, also experience a color to go along with it. Others find that words have a flavor. Still others experience colors with scents. The list goes on and on. For such people the senses bleed over into each other. This is called synesthesia and over 60 different types of it have been reported.
Some famous people have left us records that show they experienced synesthesia. Color is the easiest to describe, so we know of many famous people with that form. Leonard Bernstein, for instance, talked about timbre as color. Richard Feynman saw equations in colors. Vladimir Nabokov left descriptions of the colors and textures of specific letters. Duke Ellington talked about how the same note played by different people had different colors. Franz Liszt confused the heck out of the Weimar Orchestra by calling out, “O, please, gentlemen, a little bluer, if you please.”
Other forms, such as the tastes of sounds, are harder to describe and we know less about them in a historical context. But many of our metaphors (“a loud jacket,” “a sour voice,” etc.) suggest that human beings in general recognize, at some level, the kinship across the senses. But for most of us, it’s just that, a metaphor. We may understand, at some level, why the Blues are called the Blues, or why we talk about some noise as being “jagged,” but we can only try to imagine what the world is like for true synesthetes. Because they live in a world more complicated, but probably richer than our own.
So I can only wonder: What does a symphony taste like?