Today I've been reading This is Your Brain on Music by Daniel J. Levitin. I was calmly digesting the differentiation of neural circuits into linguistic and musical pathways, when a sentence in the text hit me right in the solar plexus. Levitin was defining synesthesia, or the rerouting of a sensory impression from one of the five senses to another. For readers, like me, encountering the concept of synesthesia for the first time, Levitin likened the phenomenon to a "psychedelic union of everything sensory" in which one might "see the number five as red, taste cheddar cheeses in D-flat, and smell roses in triangles."
As story ideas about synesthetic aliens crashed thorough my head, I dropped my book and ran to Wikipedia to learn more about synesthesia.
My first surprise was how many of my favorite composers and musicians have synesthesia: Duke Ellington, Rimsky-Korsakav, even John Mayer. I was also interested to learn that adults with synesthesia normally map one specific sense to another, such as sounds to color, or words to taste.
I am hardly the first writer to be struck by the poetic juxtaposition of tasting cheddar in D-flat or smelling in triangles. Wikipedia noted that Mary Shelly used synesthesia to describe the mental state of Frankenstein's monster before he grew fully self-aware. In Dune Frank Herbert attributes synesthetic perceptions to Paul Atreides. The melding of the senses is a mind-blowing cosmic metaphor, the union of what we perceive representing a sense of unity between the individual and the universe.
The fascination of synesthesia for me, and I suspect for the dozens of authors who have used it to describe a character's state of mind, is exactly that power of perception. Every author builds the relationship between reader and character through the use of sensory details. Readers see what a protagonist sees- hears, tastes, touches, and smells what the character does. Tampering with the reader's expectations of the character's sensory mapping, plunges the reader farther from the world as he knows it, and deeper into the experience of the protagonist.
