SynaesthesiaSynaesthesia is the neurological mixing of the senses. A synaesthetic may for example hear colors, see sounds, and taste tactile sensations. While this may happen in a person who has autism, it is by no means exclusive to autistics.
Synaesthetics often experience correspondences between the shades of color, tone of sounds, and intensity of taste that they assosiate with an alternate sensation. For instance, a synaestetic may see a more intense red as the pitch of a sound gets higher, or a smoother surface might make him taste a sweeter taste.
- "Franz Liszt, the 19th century composer, pianist, and conductor, saw colors in his mind's eye when he heard music? He experienced a rare phenomenon called color hearing, (in which) the senses become crossed and every musical sound is shadowed by colorful, formless visual imagery. And so, Liszt would instruct an orchestra, 'Please gentlemen, a little bluer if you please. This key demands it.'"
- --Robert Jourdain, Music, The Brain, & Ecstasy - How Music Captures Our Imagination
- "...it has to do with shamanism that is based on the use of DMT in plants. DMT is a neurotransmitter that, when ingested and allowed to come to rest in unusually large amounts in the synapses of the brain, allows one to see sound, so that one can use the voice to produce not musical compositions, but pictorial and visual compositions. This, to my mind, indicates that we're on the cusp of some kind of evolutionary transition in the language-forming area, so that we are going to go from a language that is heard to a language that is seen, through a shift in interior processing. The language will still be made of sound, but it will be processed as the carrier of the visual impression. This is actually being done by shamans in the Amazon. The songs they sing sound as they do in order to look a certain way. They are not musical compositions as we're used to thinking of them. They are pictorial art that is caused by audio signals."
- --Terence McKenna, The Archaic Revival
-  Crétien van Campen, 'Artistic and psychological experiments with synesthesia' gives the historical background.
-  nature of the cross-modal perceptions and "distinguishes it from metaphor, literary tropes, sound symbolism, and deliberate artistic contrivances that sometimes employ the term "synesthesia" to describe their multisensory joinings.