Synesthesia What Is Synesthesia? Synesthesia

Synesthesia

What is synesthesia?

Synesthesia means "joined perception" (Phillips, 2010). In the simplest terms, synesthesia refers to a condition in which a person has cross-sensory experiences, such as seeing colors in sounds, tastes, smells, cutaneous experiences, or even numbers or letters of the alphabet (Birren, 1961). In more complex terms, it has been described as the condition in which " a stimulus elicits an image in a sensory mode other than the one in which the initiating stimulus is presented," such as smelling sights, hearing tastes, or touching colors (Roeckelein, 2004). Although the phenomenon was first documented around 1873, Sir Francis Galton is generally credited with its "discovery" ten years later (Roeckelein, 2004). Galton referred to those with the condition as "color-thinkers" (Birren, 1961). In 1955, Simpson and McKellar devised a method for categorizing the different types of synesthesia by using two hyphenated words -- the first for the imagery and the second for the sensation (Roeckelein, 2004). For example, someone with gustatory-visual synesthesia would experience "taste imagery" to accompany the sight of colors (Roeckelein, 2004). Since its discovery, synesthesia has been a popular topic of research, discussion, and speculation in certain scientific circles; today there are entire websites devoted to the subject.

The most common form of synesthesia is known as "colored numbers," referring to the condition in which a person always associates numbers or letters with specific colors (Phillips, 2010). In the rarest of cases, a person may experience three or more senses from an initial stimulus, such as smelling and feeling a color (Phillips, 2010). As would be expected, every case of synesthesia varies in the particular sensory associations that are made; for instance, one may see the number one as red, while another will see it as white (Phillips, 2010).

It's difficult to measure the percentage of people who experience synesthesia since it does not affect other abilities, and many people either don't know they have it, don't know what to call it, or believe that everyone has similar experiences. In addition, everyone has synesthetic experiences to some degree, such as "seeing red" or "feeling blue." Synesthesia is most often found in women, left-handed people, and those with average to above average intelligence (Phillips, 2010). It is also thought to be a dominant trait inherited via the X-chromosome (Phillips, 2010).

How is it diagnosed?

Various tests have been developed to help diagnose synesthesia, and a few can be found online. But one of the leading synesthesia researchers, Dr. Richard Cytowic, has compiled a list of standards that he believes must be met for a diagnosis. These standards describe synesthetic perceptions as: involuntary, projected rather than imagined, constant over time, emotion-provoking, and simple in nature (Phillips, 2010). In addition, people with synesthesia often mix-up the initial perception with the accompanying sensation; for example, a person who sees the color red when hearing the name "Bruce" might better associate Bruce himself with red than with the name Bruce (Phillips, 2010).

Underlying neurological mechanisms

Synesthesia has been recognized as innate and hereditary almost since its discovery (Birren, 1961), and was initially associated with mental illness, powerful emotional associations tied to early experiencs, or simply an overactive imagination (Nelson & Hitchon, 1999). In 1946, a "modern psychology" researcher claimed that synesthesia "is a frequent characteristic of individuals who in other ways manifest degenerative symptoms" (Harriman, 1946).

Today the condition is studied most often by neurologists and psychologists. The latest research indicates that early memories and experiences do not form the basis for the synesthetists' cross-perceptions, and it is no longer linked to mental illness or brain degeneration. Instead, current research is interested in the correlation between synesthesia and left-handedness, since left-handedness is known to be associated with other unusual "cross-wiring" in the brain (the "right" or creative side of the brain is more dominant). Brain imaging proves the cross-linking concept in that for someone with visual-gustatory synesthesia, the taste center of the brain will be activated along with the visual centers (visual cerebral cortex) when a person is given a visual cue (Roeckelein, 2004). Synesthesia is also thought to involve anomalies in the brain's limbic system, which not only controls the coordination of senses, but some information-processing activities as well (Roeckelein, 2004; Phillips, 2010). In addition, some researchers believe that everyone is born with "cross-wiring," but this wiring is refined and "corrected" with experience (Phillips, 2010). Finally, in a 2009 study, researchers found evidence to suggest that synesthetic experiences are "driven by late, perceptual processing, rather than early, unisensory processing"; this finding supports the hypothesis that synesthesia is related to activity in the brains' information-processing and sense-processing limbic system (Bargary & al, 2009).

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