History of Synesthesia
Synesthesia has been known to medicine for almost three hundred years. After interest peaked between 1860 and 1930, it was forgotten, because psychology and neurology were premature sciences. Psychological theory was full with associations, and concepts of nervous tissue were insignificant. Subjective experience, such as synesthesia, was believed not a proper subject for scientific study.(pg3)
Synesthesia's history is interesting but also important if we are to understand its neurological basis, because the word was used to describe diverse phenomena in different eras. Central to the initial approach in 1980 was a sharp separation of synesthesia as a sensual perception as distinct from a mental object like cross-modal associations in non-synesthetes, metaphoric language, or even artistic aspirations to sensory fusion. By contrast, the perceptual phenomenon is unheard-of in literary and linguistic circles, where the term "synesthesia" is understood to mean rhetorical tropes (figures of speech) or sound symbolism. Whether such a division remains warranted is considered.(pg10)
Synesthesia attracted attention in art, music, literature, linguistics, natural philosophy, and theosophy. Most accounts emphasized colored hearing, the most common form of synesthesia.
This imbalance in the types of synesthesia is fascinating. The five senses can have ten possible synesthetic pairings. Synesthetic relationships are usually unidirectional, however, meaning that for a particular synesthete sight may induce touch, but touch does not induce Visual perceptions. This one-way street, therefore, increases the permutations to twenty (or thirty if you include the perception of movement as a sixth element), yet some senses, like sight and sound, are involved much more often than others. To people with gifted colored hearing, for example, speech and music are not only heard but also a visual melange of colored shapes, movement, and scintillation. (Vilayanur S. Ramachandran and Edward M. Hubbard)
It is rare for smell and taste to be either the trigger or the synesthetic response. There are findings in which sight evokes smell, in which taste and smell evoked widespread experience, I have found none in which smell itself is the trigger. The strangest synesthesia is "audio motor," in which an experiment was done and an adolescent positioned his body in different postures according to the sounds of different words. Both English and nonsense sounds had certain physical movements, the boy claimed, which he could demonstrate by striking various poses. By way of convincing himself of this sound-to-movement association, the physician who described it planned to re-test the boy later on without warning. When the doctor read the same word list aloud ten years later, the boy assumed, without hesitation, the identical postures of a decade earlier.(pg 20)
By mid-nineteenth century synesthesia had intrigued an art movement that sought sensory fusion, and a union of the senses appeared more and more frequently. Multimodal concerts of music and light, sometimes including odor, were popular and often featured color organs, keyboards that controlled colored lights as well as musical notes. It is imperative to understand that such deliberate contrivances are qualitatively different from the involuntary experiences that I am calling synesthesia in this review.
The Russian composer Alexander Scriabin (1872-1915) specifically sought to express his own synesthesia in his 1910 symphony Prometheus, the Poem of Fire, for orchestra, piano, organ, and choir. It also included a mute keyboard, a clavier a Lumieres, which controlled the play of colored light in the form of beams, clouds, and other shapes, flooding the concert hall and culminating in a white light so strong as to be "painful to the eyes."
Vasilly Kandinsky (1866-1944) had perhaps the deepest sympathy for sensory...