Colored Hearing: Synesthesia as an Enhanced Reality
Every human being has a different perception of the world; these contrasting perceptions, including interactions with colors and sounds, have influenced many artists in producing remarkable works of art and literature. The great Russian writer Vladimir Nabokov describes in his autobiography the intriguing relationship he has with letters and colors, something he refers to as "colored hearing": "The color sensation seems to be produced by the very act of my orally forming a given letter while I imagine its outline. The long a of the English alphabet has for me the tint of weathered wood, but a French a evokes polished ebony. This black group also includes hard g (vulcanized rubber) and r (a sooty rag being ripped). Oatmeal n, noodle-limp l, and the ivory-backed hand mirror of o take care of the whites...Since a subtle interaction exists between sound and shape, I see q as browner than k, while s is not the light blue of c, but a curious mixture of azure and mother-of-pearl." (Nabokov, 34). Nabokov's colored hearing is in fact the phenomenon of synesthesia - where two or more of the physical senses evoke concomitant feelings or perceptions.
Synesthesia is defined as a neurological state, although it is not an ailment and does not interfere with a synesthete's (one who experiences synesthesia) daily life or cognitive abilities. It is merely a case of perceptual difference, and most synesthetes think their experiences are neither positive nor negative, but sometimes even enjoyable.
There are five common types of synesthesia: grapheme-color, lexical-gustatory, ordinal-linguistic personification, musical-color, and number form. In grapheme-color synesthesia, the most common type of all, one perceives individual letters and numbers to have distinctive colors or hues, though no two synesthesia experiencing people will have the same colors for each letter. The much rarer lexical-gustatory synesthesia evokes different tastes of spoken words, like the word table triggering the taste of egg. Within ordinal-linguistic personification synesthesia, a synesthete links personalities for ordered series, like days of the week, letters, and months. For them, Tuesday might be passive, female, and colored pink, or 1984 might suggest a violent, untrusting personality. Because it is somewhat different from other types of synesthesia, and seemingly more common (children may feel this sort of personalization when learning language) it is more difficult to recognize. As the name might imply, musical-color synesthesia is when synesthetes view colors when listening to music, or even parts of music such as different tones or scales. Interestingly, the hue or color of a sound can be affected by varying pitches. Number form synesthesia allows those who experience it to form a mental number map that appears unintentionally whenever one thinks of a number. This type of synesthesia is speculated to occur because of a possible cross-activation of the brain's parietal lobe, since different areas of it process spatial and numerical cognition. In all of these forms, synesthetes usually have unchanged recognition of colors (a red A will always be red for them), though they all have very different experiences of how they perceive it and are affected by it.
Although synesthesia deals with such personal manners of perception, many of which every human being can "have" (like giving letters colors or personalities) due to their imagination or creative perspective, recognizing synesthesia is fairly uncomplicated. Neurologists or psychologists generally test and retest an individual over long periods of time on their perceptions of colored words and similar objects. Although synesthesia is easy to recognize and test, how to accurately diagnose and define it has been a source of debate for decades. In the last twenty years, researchers have refined the basic criteria for synesthesia; neurologists Kevin Dann and Richard Cytowic's definitions are currently the most accepted. They classify diagnosable synesthesia as having the following properties:
1. Synesthesia is involuntary and automatic. (Cytowic)
2. Synesthetic images are spatially extended, meaning they often have a definite "location". (Cytowic)
3. Synesthetic percepts are consistent and generic (i.e. simple rather than imagistic). (Cytowic)
4. Synesthesia is highly memorable. (Cytowic)
5. Synesthesia is laden with affect. (Dann)
6. Synesthesia is nonlinguistic and somewhat ineffable. (Dann)
7. Synesthesia occurs in people with normal, non-injured, non-diseased brains. (Cytowic, Dann, various).
As it is previously mentioned, synesthesia is believed to occur due to a cross-activation within areas of the brain. The area of the brain in which color processing occurs is beside the area which identifies numbers and letters; thus information may be mismanaged or cross-activated in both areas, creating the experience of synesthesia. It is speculated that synesthetes may also suffer from left-right brain confusion, and have difficulty in writing and performing mathematics. At the same time, synesthetes seem to enjoy and excel in creative activities, and offer an infinite source of research on the function of the human brain (and how information can "cross over" into other areas) as well as on states of consciousness.
Generally, synesthesia is speculated to be to an extent, hereditary. Nearly four percent of the population reports being a synesthete. These are naturally occurring, non-induced clusters of synesthesia within families, and are fairly common (for example, Nabokov's mother, like he, was a synesthete). A newer theory stemming from the hereditary synesthesia idea suggests that its mode of inheritance is due to sex - women tend to carry the "gene" for synesthesia, and are usually prevalent synesthetes. Supporting evidence of this "female gene" in synesthesia is the fact that all cases of inherited synesthesia have a female carrier or receptor, be it from mother to son or daughter, or father to daughter, but no male to male inheritance has ever been documented. Inherited synesthesia is not consistent, and like baldness, skips generations; the type of synesthesia that inherited synesthetes experience can also be vastly different.
There are also cases of adventitious synesthesia, or non-inherent synesthesia, which infer that this condition can be deliberately or naturally induced: individuals who consume psychoactive drugs, like lysergic acid diethylamide (LSD) and phencyclidine (PCP), those who experience synesthesia after a stroke or in conjunction to deafness and blindness have said to experience synesthesia or aspects of it. This sort of synesthesia "caused" by drugs or after a stroke is singular in which individuals who experience it only have synesthetic occurrences altering their musical-color, vision, or touch perceptions. Drug induced synesthesia does not last long, and since psychoactive drugs observably alter one's natural brain processes and perceptions, this type of synesthesia is not necessarily worth to research. However, non-inherent synesthesia does indicate that there is a significant link between consciousness and the condition.
Synesthesia is an uncommonly known condition, and although research and debate regarding its causes has been ongoing since the 1800s, we are nowhere near completely understanding all aspects of it. It is a distinct phenomenon with various consequences; it affects individuals and their perceptions of reality and life, and may be behind the creative genius of various artists, writers, and musicians such as Duke Ellington, Richard Feynman, Franz Liszt, Victor Hugo (American Synesthesia Association, site), and many others who, though have not been classified as full synesthetes, are pseudo-synesthetes, or merely incorporate synesthetic aspects into their work. Above all, synesthesia is also a prime example of our limited knowledge of the capability of the human brain as we know it. The simple fact that synesthesia exists can give us all hope that the key to discovering the immeasurable possibilities of our brains, and even realities, may be one day unlocked.
American Synesthesia Association. 2006. < http://www.synesthesia.info/abstracts.html>
Cytowic, R.E. Synesthesia: A Union of the Senses, 2nd ed. Massachusetts: MIT Press, 2002.
Cytowic, R.E. Synesthesia: Phenomenology And Neuropsychology
A Review of Current Knowledge. 2006. <http://psyche.cs.monash.edu.au/v2/psyche-2-10-cytowic.html>
Dann, K.T. Bright Colors Falsely Seen: Synaesthesia and the Search for Transcendent Knowledge. Yale University Press, 1998.
Eagleman, David M. The Laboratory for Perception and Action. 2006. <http://nba.uth.tmc.edu/homepage/eagleman/> (various links and articles from there as well).
Green, Jennifer. "Synaesthesia And Education." University of Cambridge Faculty of Education. 2006. Cambridge University. <http://www.educ.cam.ac.uk/synaesthesia/whatis.html>.
Nabokov, Vladimir. Speak Memory. New York: Vintage International, 1989. 34.
UK Synaesthesia Association. 2006. <http://www.uksynaesthesia.com/>
* A link of note: If you think you might be a synesthete, you can take the Synesthesia Battery of tests and find out while contributing to research (pretty cool). Go to http://synesthete.org/.