Synesthesia (also spelled synaesthesia) is a neurological phenomenon in which stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway. People who report such experiences are known as synesthetes. There are two overall forms of synesthesia: projecting synesthesia and associative synesthesia. People who project will see actual colors, forms, or shapes when stimulated, as is commonly accepted as synesthesia; associators will feel a very strong and involuntary connection between the stimulus and the sense that it triggers. Some synesthetes often report that they were unaware their experiences were unusual until they realized other people did not have them, while others report feeling as if they had been keeping a secret their entire lives.
Quote: "Synesthesia runs strongly in families, but the precise mode of inheritance has yet to be ascertained."
Synesthesia is a neurologically based condition in which stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway.
Synesthesia literally refers to the fact that in some animals, a stimulus in one sense modality involuntarily elicits a sensation/experience in another sense modality. An example of this would be the taste of lemon visually evoking the color blue. The elicited synesthetic experience does not replace the normal experience but instead always adds to it. Synesthetic elicitations are durable, consistent, and discrete, as noted by Dr. Cytowic.
Estimates for the number of people with synesthesia range from 1 in 200 to 1 in 100,000. There are probably many people who have the condition but do not realize what it is. Synesthesia runs strongly in families, but the precise mode of inheritance has yet to be ascertained. Synesthesia is also sometimes reported by individuals under the influence of psychedelic drugs, after a stroke, during a temporal lobe epilepsy seizure, or as a result of blindness or deafness.
For scientists, synesthesia presents an intriguing problem. Studies have confirmed that the phenomenon is biological, automatic and apparently unlearned, distinct from both hallucination and metaphor. The condition runs in families and is more common among women than men, researchers now know. But until recently, researchers could only speculate about the causes of synesthesia. Now, however, modern behavioral, brain-imaging and molecular genetic tools hold exciting promise for uncovering the mechanisms that drive synesthesia and researchers hope for better understanding how the brain normally organizes perception and cognition.
Over 60 types of synesthesia have been reported.
In one common form of synesthesia, known as grapheme color synesthesia or color-graphemic synesthesia, letters or numbers are perceived as inherently colored, while in ordinal linguistic personification, numbers, days of the week and months of the year evoke personalities.
In spatial-sequence, or number form synesthesia, numbers, months of the year, and/or days of the week elicit precise locations in space (for example, 1970 may be "farther away" than 1980), or may have a (three-dimensional) view of a year as a map.
Yet another recently identified type, visual motion sound synesthesia, involves hearing sounds in response to visual motion and flicker.
Emotions - colors
Emotion - smell
Emotion - flavor
Emotion - pain
Emotion - smell
Emotion - temperature
Emotion - touch
Flavors - colors
Flavors - sounds
Flavors - temperatures
Flavors - touch
General sounds - colors
Graphemes - colors
Grapheme - flavor
Kinetics - colors
Kinetics - sounds
Lexeme - touch
Musical notes - colors
Musical notes - flavors
Musical sounds - colors
Odors - colors
Orgasm - colors
Pain - colors
Pain - flavor
Pain - smell
Pain - sound
Personalities - smells
Personalities - touch
Personalities - colors (auras)
Phoneme - touch
Phoneme - flavor
Phonemes - colors
Smells - flavor
Smells - sounds
Smells - temperatures
Smells - touch
Sound - flavors
Sounds - kinetics
Sounds - smells
Sound - temperatures
Sound - touch
Temperatures - colors
Temperature - flavors
Temperatures - sounds
Time units - colors
Touch - colors
Touch - emotions
Touch - flavors
Touch - smell
Touch - sounds
Touch - temperatures
Vision - flavors
Vision - kinetics
Vision - smells
Vision - sounds
Vision - Temperatures
Vision - touch
Neurologist Richard Cytowic identifies the following diagnostic criteria of synesthesia:
People who report such experiences are known as synesthetes. Most synesthetes report that their experiences are neutral, or even pleasant.
Synesthetes often report that they were unaware their experiences were unusual until they realized other people did not have them, while others report feeling as if they had been keeping a secret their entire live
Many people with synesthesia use their experiences to aid in their creative process, and many non-synesthetes have attempted to create works of art that may capture what it is like to experience synesthesia.
Eddie Van Halen
Ida Maria Borli Sivertsen
Karl Robert Osten-Sacken
Sir Robert Cailliau
Under Review - List of famous people who may have, or had, Synesthesia:
Are you a Synesthete?
Visit "The Synesthesia Battery" at synesthete.org to take an online test to find out.
Although often termed a "neurological condition," synesthesia is not listed in either the DSM-IV or the ICD since it most often does not interfere with normal daily functioning.
Depending on the study, researchers have suggested 1 in 2,000 people have some form of synesthesia, while others have reported 1 in 300 or even as many as 1 in 23. One problem with statistics is that some individuals will not self-classify as they do not realize that their perceptions are different from those of everyone else.
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