Imagine that every time you saw the number 4, it would be eggshell blue; or every time you heard an F tone you saw a crisp purple arc half a foot in front of you.
Synesthetic perception can occur between any 2 senses. Probably the most common type of synesthesia is grapheme—color (chromatographemic) synesthesia. For the life of the synesthete, letters and numbers are tinged with a particular shade or color. Attending a cocktail party a few years ago, I was chatting about the subject when a handsome stranger suddenly blurted: ”4 is Green! Lettuce is 4!” In his 40s, this eavesdropping attorney had never known there was a name for this peculiarity in his perception. Like most synesthetes, he assumed everyone saw the way he did until an experience at school had him realize he was ‘different’, & he had never mentioned it to anyone until the day we spoke. He later discovered that his father also saw certain letters and numbers shaded. Research does indicate that synesthesia is to some extent hereditary.Synesthesia usually doesn’t interfere with day to day life. There are 8 times as many synesthetes working in the creative professions – artists, poets, writers, musicians – than in the general population.
Many synesthetes find that having linked senses assists them in tasks of memorization.
Musician Noriko Nagata who sees colors in sounds (chromestesia – colored-hearing synesthesia) reports, “As I was receiving professional education in music (I also have a sense of perfect pitch), the resonance of a sound and the image of a color have always been deeply connected. When it came to composing music, I would think, "I will make blue colored music", or think, "What were these codes I remembered in pink and beige?" during a test on guessing the right code names of tension codes. It has been my habit since I was small to feel colors and memorize things in colors using this way.”Examples of some more elaborate forms of synesthesia follow:
Some synesthetes taste shapes: ergo the statement, ‘There aren’t enough points in the chicken.’ The taste of roast chicken made this synesthete feel a round shape in his hands, as if he were rubbing a bowling ball instead of feeling the prickly shape he expected. (Cytowic, “The Man who Tasted Shapes”, MIT Press p.11)
Others upon hearing a sound see light, color and identifiable images. ‘Presented with a tone pitched @ 250Hz amplitude 64db, S saw a velvet cord with fibres jutting out on all sides. The cord was tinged with a delicate, pleasant pink-orange hue… Presented with a tone pitched @ 3000Hz amplitude 113db, he saw a whisk broom that was of a fiery color, while the rod attached to the whisks seemed to be scattering off into fiery points. The experiments were repeated during several days and invariably the same stimuli produced identical experiences.” (Baron-Cohen & Harrison, "Synaesthesia: Classic and Contemporary Readings", Blackwell Publishers, Cambridge, MA, p.102)
MIT's 'The Synesthetic Experience' has a couple of on-line demos simulating synesthetic experience, and accounts of first-hand experiences of synesthesia.
