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Synesthesia



 
 
"Synopsia" redirects here. For the geometer moth
Geometer moth

The geometer moths or Geometridae are a family of the order Lepidoptera. A very large family, it has around 26,000 species of moths described ....
 genus
Genus

A genus is a low-level taxonomic rank used in the classification of living and fossil organisms. The taxonomic ranks are domain , kingdom , phylum, class , order , family , genus, and species....
, see
Synopsia (moth).
Synesthesia (also spelled synæsthesia or synaesthesia, plural synesthesiae or synaesthesiae)—from the Ancient Greek (syn), "together," and (aisthesis), "sensation
Sensation

Sensation is the Fiction-writing modes for portraying a character's perception of the senses. According to Ron Rozelle, ?. . .the success of your story or novel will depend on many things, but the most crucial is your ability to bring your reader into it....
" — is a neurologically based phenomenon in which stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway.






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"Synopsia" redirects here. For the geometer moth
Geometer moth

The geometer moths or Geometridae are a family of the order Lepidoptera. A very large family, it has around 26,000 species of moths described ....
 genus
Genus

A genus is a low-level taxonomic rank used in the classification of living and fossil organisms. The taxonomic ranks are domain , kingdom , phylum, class , order , family , genus, and species....
, see
Synopsia (moth).
Synesthesia (also spelled synæsthesia or synaesthesia, plural synesthesiae or synaesthesiae)—from the Ancient Greek (syn), "together," and (aisthesis), "sensation
Sensation

Sensation is the Fiction-writing modes for portraying a character's perception of the senses. According to Ron Rozelle, ?. . .the success of your story or novel will depend on many things, but the most crucial is your ability to bring your reader into it....
" — is a neurologically based 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.

In one common form of synesthesia, known as grapheme ? color synesthesia
Grapheme-color synesthesia

Grapheme ? color synesthesia is a form of synesthesia in which an individual's perception of numbers and letters is associated with the experience of colors....
 or color-graphemic synesthesia, letter
Letter (alphabet)

A letter is an element in an alphabetic system of writing, such as the Greek alphabet and its descendants. Each letter in the written language is usually associated with one phoneme in the spoken form of the language....
s or numbers
Numerical digit

In mathematics and computer science, a digit is a symbol used in numerals , to represent numbers, in Positional notation numeral systems. The name "digit" comes from the fact that the 10 digits of the hands correspond to the 10 symbols of the common base 10 number system, i.e....
 are perceived as inherently colored, while in ordinal linguistic personification
Ordinal linguistic personification

Ordinal-linguistic personification is a form of synesthesia in which ordered sequences, such as ordinal numbers, week-day names, months and Letter are associated with personalities ....
, numbers, days of the week and months of the year evoke personalities. In spatial-sequence, or number form
Number form

A number form is a mental map of numbers, which Automaticity and involuntarily appears whenever someone who experiences number-forms thinks of numbers....
 synesthesia, numbers, months of the year, and/or days of the week elicit precise locations in space (for example, 1980 may be "farther away" than 1990), or may have a (three-dimensional) view of a year as a map (clockwise or counterclockwise). Yet another recently identified type, visual motion ? sound synesthesia, involves hearing sounds in response to visual motion and flicker. Over 60 types of synesthesia have been reported by people, but only a fraction has been evaluated by scientific research. Even within one type, synesthetic perceptions vary in intensity and people vary in awareness of their synesthetic perceptions.

While cross-sensory metaphor
Metaphor

Metaphor is language that directly compares seemingly unrelated subjects. It is a figure of speech that compares two or more things without using the words "like" or "as." More generally, a metaphor describes a first subject as being or equal to a second object in some way....
s (e.g., "loud shirt," "bitter wind" or "prickly laugh") are sometimes described as "synesthetic," true neurological synesthesia is involuntary. It is estimated that synesthesia could possibly be as prevalent as 1 in 23 persons across its range of variants. 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 drug
Psychedelic drug

A psychedelic substance is any psychoactive drugs whose primary action is to alter the thought processes of the brain and perception of the mind....
s, after a stroke
Stroke

A stroke is the rapidly developing loss of brain function due to a disturbance in the blood supply to the brain. According to the National Stroke Association, a "stroke" occurs when a blood clot blocks and artery or a blood vessel breaks, interrupting blood flow to an area of the brain....
, during a temporal lobe epilepsy
Temporal lobe epilepsy

Temporal lobe epilepsy is a form of Focal seizures epilepsy, a chronic neurology condition characterized by recurrent seizures. While focal epilepsy accounts for about 50% of all epilepsy cases, the prevalence of temporal lobe epilepsy among these cases remains uncertain....
 seizure, or as a consequence of blindness
Blindness

Blindness is the condition of lacking visual perception due to physiological or neurological factors.Various scales have been developed to describe the extent of vision loss and define "blindness." Total blindness is the complete lack of form and visual light perception and is clinically recorded as "NLP," an abbreviation for "no ligh...
 or deafness. Synesthesia that arises from such non-genetic events is referred to as "adventitious synesthesia" to distinguish it from the more common congenital forms of synesthesia. Adventitious synesthesia involving drugs or stroke (but not blindness or deafness) apparently only involves sensory linkings such as sound ? vision or touch ? hearing; there are few, if any, reported cases involving culture-based, learned sets such as graphemes, lexemes, days of the week, or months of the year.

Although synesthesia was the topic of intensive scientific investigation in the late 1800s and early 1900s, it was largely abandoned by scientific research in the mid-20th century, and has only recently been rediscovered by modern researchers. Psychological
Psychology

Psychology is an academic and applied science discipline involving the science study of human mental functions and behavior. Occasionally it also relies on symbolic hermeneutics and critical theory, although these traditions are less pronounced than in other social sciences such as sociology....
 research has demonstrated that synesthetic experiences can have measurable behavioral consequences, while functional neuroimaging
Functional neuroimaging

Functional neuroimaging is the use of neuroimaging technology to measure an aspect of brain function, often with a view to understanding the relationship between activity in certain brain areas and specific mental functions....
 studies have identified differences in patterns of brain activation. 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. Psychologists and neuroscientists study synesthesia not only for its inherent interest, but also for the insights it may give into cognitive and perceptual processes that occur in synesthetes and non-synesthetes alike.

Definitional criteria

Although sometimes spoken of as a "neurological condition," synesthesia is not listed in either the DSM-IV or the ICD
ICD

The International Statistical Classification of Diseases and Related Health Problems provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings,...
 classifications, since it does not, in general, interfere with normal daily functioning. Indeed most synesthetes report that their experiences are neutral, or even pleasant. Rather, like color blindness
Color blindness

Color blindness, a color vision deficiency, is the inability to perceive differences between some of the colors that others can distinguish. It is most often of genetic nature, but may also occur because of eye, nerve, or brain damage, or due to exposure to certain chemicals....
 or perfect pitch, synesthesia is a difference in perceptual experience and the term "neurological" simply reflects the brain basis of this perceptual difference. To date, no research has demonstrated a consistent association between synesthetic experience and other neurological or psychiatric conditions, although this is an active area of research (see below for associated cognitive traits).

It was once assumed that synesthetic experiences were entirely different from synesthete to synesthete, but recent research has shown that there are underlying similarities that can be observed when large numbers of synesthetes are examined together. For example, sound-color synesthetes, as a group, tend to see lighter colors for higher sounds and grapheme-color synesthetes, as a group, share significant preferences for the color of each letter (e.g., A tends to be red; O tends to be white or black; S tends to be yellow etc.,). Nonetheless, there are a great number of types of synesthesia, and within each type, individuals can report differing triggers for their sensations, and differing intensities of experiences. This variety means that defining synesthesia in an individual is difficult, and indeed, the majority of synesthetes are not aware that their experiences have a name. However, despite the differences between individuals, there are a few common elements that define a true synesthetic experience.

Neurologist Richard Cytowic identifies the following diagnostic criteria of synesthesia:
  1. Synesthetic images are spatially extended, meaning they often have a definite "location."
  2. Synesthesia is involuntary and automatic
    Automaticity

    Automaticity is the ability to do things without occupying the mind with the low level details required. It is usually the result of learning, repetition , and practice....
    .
  3. Synesthetic percepts are consistent and generic (i.e. simple rather than imagistic).
  4. Synesthesia is highly memorable
    Memory

    In psychology, memory is an organism's mental ability to store, retain and recall information. Traditional studies of memory began in the fields of philosophy, including techniques of mnemonic....
    .
  5. Synesthesia is laden with affect
    Affect (psychology)

    Affect, like the adjective affective, refers to the experience of feeling or emotion. Affect is a key part of the process of an organism?s interaction with stimuli....
    .


Although Cytowic suggested that synesthetic experiences are necessarily spatially extended, more recent research has shown many cases where this is not true. For example, some synesthetes "know" the color of their letters or the taste of their words, but do not experience them as a color in space or a taste on the tongue (see below).

Experiences

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, as has been documented in interviews with synesthetes on how they discovered synesthesia in their childhood. The automatic and ineffable nature of a synesthetic experience means that the pairing may not seem out of the ordinary. This involuntary and consistent nature helps define synesthesia as a real experience. Most synesthetes report that their experiences are pleasant or neutral, although, in rare cases, synesthetes report that their experiences can lead to a degree of sensory overload.

Though often stereotyped in the popular media as a medical condition or neurological aberration, synesthetes themselves do not experience their synesthetic perceptions as a handicap. To the contrary, most report it as a gift—an additional "hidden" sense—something they would not want to miss. Most synesthetes have become aware of their "hidden" and different way of perceiving in their childhood. Some have learned how to apply this gift in daily life and work. Synesthetes have used their gift in memorizing names and telephone numbers, mental arithmetic, but also in more complex creative activities like producing visual art, music, and theater.

Despite the commonalities which permit definition of the broad phenomenon of synesthesia, individual experiences vary in numerous ways. This variability was first noticed early on in synesthesia research but has only recently come to be re-appreciated by modern researchers. Some grapheme ? color synesthetes report that the colors seem to be "projected" out into the world, while most report that the colors are experienced in their "mind's eye." Additionally, some grapheme ? color synesthetes report that they experience their colors strongly, and show perceptual enhancement on the perceptual tasks described below, while others (perhaps the majority) do not, perhaps due to differences in the stage at which colors are evoked. Some synesthetes report that vowel
Vowel

In phonetics, a vowel is a sound in spoken language, such as English ah! or oh! , pronounced with an open vocal tract so that there is no build-up of air pressure at any point above the glottis....
s are more strongly colored, while for others consonant
Consonant

In articulatory phonetics, a consonant is a speech sound that is articulated with complete or partial closure of the upper vocal tract, the upper vocal tract being defined as that part of the vocal tract that lies above the larynx....
s are more strongly colored. In summary, self reports, autobiographical notes by synesthetes and interviews show a large variety in types of synesthesia, intensity of the synesthetic perceptions, awareness of the difference in perceiving the physical world from other people, the way they creatively use their synesthesia in work and daily life. The descriptions below give some examples of synesthetes' experiences, which have been experimentally tested, but do not exhaust their rich variety.

Various forms

Synesthesia can occur between nearly any two senses or perceptual modes. Given the large number of forms of synesthesia, researchers have adopted a convention of indicating the type of synesthesia by using the following notation x ? y, where x is the "inducer" or trigger experience, and y is the "concurrent" or additional experience. For example, perceiving letters and numbers (collectively called grapheme
Grapheme

In typography, a grapheme is the fundamental unit in writing systems. Graphemes include letter , Chinese characters, numerals, punctuation marks, and all the individual symbols of any of the world's writing systems....
s) as colored would be indicated as grapheme ? color synesthesia. Similarly, when synesthetes see colors and movement as a result of hearing musical tones, it would be indicated as tone ? (color, movement) synesthesia.

While nearly every logically possible combination of experiences can occur, several types are more common than others.

Grapheme ? color synesthesia


In one of the most common forms of synesthesia, grapheme ? color synesthesia, individual letters of the alphabet and numbers (collectively referred to as grapheme
Grapheme

In typography, a grapheme is the fundamental unit in writing systems. Graphemes include letter , Chinese characters, numerals, punctuation marks, and all the individual symbols of any of the world's writing systems....
s), are "shaded" or "tinged" with a color
Color

Color or colour is the visual perception property corresponding in humans to the categories called red, yellow, blue and others....
. While synesthetes do not, in general, report the same colors for all letters and numbers, studies of large numbers of synesthetes find that there are some commonalities across letters (e.g., A is likely to be red).

A grapheme ? color synesthete reports, "I often associate letters and numbers with colors. Every digit and every letter has a color associated with it in my head. Sometimes, when letters are written boldly on a piece of paper, they will briefly appear to be that color if I'm not focusing on it. Some examples: 'S' is red, 'H' is orange, 'C' is yellow, 'J' is yellow-green, 'G' is green, 'E' is blue, 'X' is purple, 'I' is pale yellow, '2' is tan, '1' is white. If I write SHCJGEX it registers as a rainbow when I read over it, as does ABCPDEF."

Another reports a similar experience. "When people ask me about the sensation, they might ask, 'so when you look at a page of text, it's a rainbow of color?' It isn't exactly like that for me. When I read words, about five words around the exact one I'm reading are in color. It's also the only way I can spell. I remember in elementary school remembering how to spell the word 'priority' because the color scheme, in general, was darker than many other words. I would know that an 'e' was out of place in that word because e's were yellow and didn't fit."

Another reports a slightly different experience. "When I actually look at words on a page, the letters themselves are not colored, but instead in my mind they all have a color that goes along with them, and it has always been this way. I remember back in kindergarten thinking that each homeroom had a different color associated with it. I would sometimes say things referring to that class and calling it by its color. It is also like this with days of the week, months, and so on. I thought this was caused by me over-thinking things. But I finally have come to realize that Synesthesia is real."

Sound ? color synesthesia

In sound ? color synesthesia, individuals experience colors in response to tones or other aspects of sounds. Simon Baron-Cohen
Simon Baron-Cohen

Simon Baron-Cohen is Professor of Developmental Psychopathology in the Departments of Psychiatry and Experimental Psychology, a Fellow of Trinity College, Cambridge, and Director of the Autism Research Centre at the University of Cambridge, in the United Kingdom....
 and his colleagues break this type of synesthesia into two categories, which they call "narrow band" and "broad band" sound ? color synesthesia. In narrow band sound ? color synesthesia (often called music ? color synesthesia), musical stimuli (e.g., timbre or key) will elicit specific color experiences, such that a particular note will always elicit red, or harps will always elicit the experience of seeing a golden color. In broadband sound ? color synesthesia, on the other hand, a variety of environmental sounds, like an alarm clock or a door closing, may also elicit visual experiences.

Color changes in response to different aspects of sound stimuli may involve more than just the hue of the color. Any dimension of color experience (see HSL color space
HSL color space

HSL and HSV are two related representations of points in an RGB color space, which attempt to describe perceptual color relationships more accurately than RGB, while remaining computationally simple....
) can vary. Brightness (the amount of white in a color; as brightness is removed from red, for example, it fades into a brown and finally to black), saturation
Saturation (color theory)

In colorimetry and color theory, colorfulness, chroma, and saturation are related but distinct concepts referring to the perceived intensity of a specific color....
 (the intensity of the color; fire engine red
Fire engine red

Fire engine red is an intense, bright red commonly used on emergency vehicles; mostly on, as the name implies, fire apparatus.Most traditional older fire departments in larger Central City of major metropolitan areas use this color for their fire engines, but many smaller City and also many suburbs now use the color Chartreuse yellow for t...
 and medium blue are highly saturated, while grays, white, and black are all unsaturated), and hue
Hue

Hue is one of the main properties of a color described with names such as "red", "yellow", etc. The two other main properties are lightness and colorfulness....
 may all be affected to varying degrees. Additionally, music ? color synesthetes, unlike grapheme ? color synesthetes, often report that the colors move, or stream into and out of their field of view.

Like grapheme ? color synesthesia, there is rarely agreement among music ? color synesthetes that a given tone will be a certain color. However, when larger samples are studied, consistent trends can be found, such that higher pitched notes are experienced as being more brightly colored. The presence of similar patterns of pitch-brightness matching in non-synesthetic subjects suggests that this form of synesthesia shares mechanisms with non-synesthetes.

Number form synesthesia


A number form is a mental map of numbers, which automatically and involuntarily appears whenever someone who experiences number-forms thinks of numbers. Number forms were first documented and named by Francis Galton
Francis Galton

Sir Francis Galton Fellow of the Royal Society , Cousin#Half_cousins of Charles Darwin, was an England Victorian era polymath, anthropologist, Eugenics, tropical List of explorers, geographer, inventor, meteorologist, proto-geneticist, Psychometrics, and statistician....
 in "The Visions of Sane Persons". Later research has identified them as a type of synesthesia. In particular, it has been suggested that number-forms are a result of "cross-activation" between regions of the parietal lobe
Parietal lobe

The parietal lobe is a lobe in the brain. It is positioned above the occipital lobe and behind the frontal lobe.The parietal lobe integrates sensory information from different sensory modality, particularly determining spatial sense and navigation....
 that are involved in numerical
Numerical cognition

Numerical cognition is a subdiscipline of cognitive science that studies the cognitive, developmental and neural bases of numbers and mathematics....
 cognition
Cognition

Cognition is the science term for "the process of thought."Its usage varies in different ways in accord with different disciplines: For example, in psychology and cognitive science it refers to an information processing view of an individual's psychological Functionalism s....
 and spatial cognition. In addition to its interest as a form of synesthesia, researchers in numerical cognition have begun to explore this form of synesthesia for the insights that it may provide into the neural mechanisms of numerical-spatial associations present unconsciously in everyone.

Personification

Ordinal-linguistic personification (OLP, or personification for short) is a form of synesthesia in which ordered sequences, such as ordinal number
Ordinal number

In set theory, an ordinal number, or just ordinal, is the order type of a well-order. They are usually identified with hereditarily transitive sets....
s, days, months and letters
Letter (alphabet)

A letter is an element in an alphabetic system of writing, such as the Greek alphabet and its descendants. Each letter in the written language is usually associated with one phoneme in the spoken form of the language....
 are associated with personalities. Although this form of synesthesia was documented as early as the 1890s modern research has, until recently, paid little attention to this form.

For some people in addition to numbers and other ordinal sequences, objects are sometimes imbued with a sense of personality, sometimes referred to as a type of animism
Animism

Animism is a philosophical, religious or spiritual idea that souls or spirits exist not only in humans and animals but also in plants, rock s, natural phenomena such as thunder, geographic features such as mountains or rivers, or other entities of the natural environment, a proposition also known as hylozoism in philosophy....
. This type of synesthesia is harder to distinguish from non-synesthetic associations. However, recent research has begun to show that this form of synesthesia co-varies with other forms of synesthesia, and is consistent and automatic, as required to be counted as a form of synesthesia.

Lexical ? gustatory synesthesia

In a rare form of synesthesia, lexical ? gustatory synesthesia, individual words and phonemes of spoken language evoke the sensations of taste in the mouth.

Jamie Ward and Julia Simner have extensively studied this form of synesthesia, and have found that the synesthetic associations are constrained by early food experiences. For example, James Wannerton has no synesthetic experiences of coffee or curry, even though he consumes them regularly as an adult. Conversely, he tastes certain breakfast cereals and candies that are no longer sold.

Additionally, these early food experiences are often paired with tastes based on the phonemes in the name of the word (e.g., /I/, /n/ and /s/ trigger James Wannerton’s taste of mince) although others have less obvious roots (e.g., /f/ triggers sherbet). To show that phonemes, rather than graphemes are the critical triggers of tastes, Ward and Simner showed that, for James Wannerton, the taste of egg is associated to the phoneme /k/, whether spelled with a "c" (e.g., accept), "k" (e.g., York), "ck" (e.g., chuck) or "x" (e.g., fax). Another source of tastes comes from semantic influences, so that food names tend to taste of the food they match, and the word "blue" tastes "inky."

Research history


The interest in colored hearing, i.e. the co-perception of colour in hearing sounds or music, dates back to Greek antiquity, when philosophers were investigating whether the colour (chroia, what we now call timbre) of music was a physical quality that could be quantified. The seventeenth-century physicist Isaac Newton tried to solve the problem by assuming that musical tones and colour tones have frequencies in common. The age-old quest for colour-pitch correspondences in order to evoke perceptions of coloured music finally resulted in the construction of color organs and performances of colored music in concert halls at the end of the nineteenth century.

The first medical description of colored hearing is found in a thesis by the German physician Sachs in 1812. The father of psychophysics
Psychophysics

Psychophysics is a subdiscipline of psychology dealing with the relationship between physical stimulus and their subjectivity correlates, or percepts....
, Gustav Fechner
Gustav Fechner

Gustav Theodor Fechner , was a Germany experimental psychologist. An early pioneer in experimental psychology and founder of psychophysics, he inspired many 20th century scientists and philosophers....
 reported on a first empirical survey of colored letter photisms among 73 synesthetes in 1871, followed in the 1880s by Francis Galton
Francis Galton

Sir Francis Galton Fellow of the Royal Society , Cousin#Half_cousins of Charles Darwin, was an England Victorian era polymath, anthropologist, Eugenics, tropical List of explorers, geographer, inventor, meteorologist, proto-geneticist, Psychometrics, and statistician....
. Following these initial observations, research into synesthesia proceeded briskly, with researchers from England, Germany, France and the United States all investigating the phenomenon. However, due to the difficulties in assessing and measuring subjective internal experiences, and the rise of behaviorism
Behaviorism

Behaviorism or Behaviourism,also called the learning perspective is a philosophy of psychology based on the proposition that all things which organisms do ? including acting, thinking and feeling?can and should be regarded as behaviors....
 in psychology, which banished any mention of internal experiences, the study of synesthesia gradually waned during the 1930s.

In the 1980s, as the cognitive revolution
Cognitive revolution

The "cognitive revolution" is the name for an intellectual movement in the 1950s that began what are known collectively as the cognitive sciences....
 had begun to make discussion of internal states and even the study of consciousness
Consciousness

Consciousness is a difficult term to define, because the word is used and understood in a wide variety of ways, so that it frequently happens that what one person sees as a definition of consciousness is seen by others as about something else altogether....
 respectable again, scientists began to once again examine this phenomenon. Led in the United States by Larry Marks and Richard Cytowic, and in England by Simon Baron-Cohen
Simon Baron-Cohen

Simon Baron-Cohen is Professor of Developmental Psychopathology in the Departments of Psychiatry and Experimental Psychology, a Fellow of Trinity College, Cambridge, and Director of the Autism Research Centre at the University of Cambridge, in the United Kingdom....
 and Jeffrey Gray, research into synesthesia began by exploring the reality, consistency and frequency of synesthetic experiences. In the late 1990s, researchers began to focus on grapheme ? color synesthesia, one of the most common and easily studied forms of synesthesia. In 2006, the journal "Cortex" published a special issue on synesthesia, composed of 26 articles. Synesthesia has been the topic of numerous scientific books, as well as novels and short films that include characters who experience some form of synesthesia.

Since the 1990s, with the rise of the internet, synesthetes started to contact each other, and create many web pages relating to the condition (see External links below). These early internet and e-mail contacts have now grown into several international organizations for synesthetes, including the American Synesthesia Association
American Synesthesia Association

The American Synesthesia Association is a not-for-profit academic and public society whose mission is to foster and promote the education and the advancement of knowledge of the phenomena of synesthesia, a neurological condition in which stimulation in one sensory modality leads to experiences in a second, unstimulated modality....
, the UK Synaesthesia Association
UK Synaesthesia Association

The UK Synaesthesia Association was originally founded by Professor Simon Baron-Cohen, Professor of Developmental Psychopathology at Cambridge University and a leading researcher into synesthesia....
, the Belgian Synaesthesia Association, the German Synesthesia Association and the Netherlands Synesthesia Web Community.

Prevalence and genetic basis

Estimates of the prevalence of synesthesia have varied widely (from 1 in 20 to 1 in 20,000). However, these studies all suffered from the methodological shortcoming of relying on self-selected
Self-selection

Self-selection is a term used to indicate any situation in which individuals select themselves into a group , causing a biased sample. It is commonly used to describe situations where the characteristics of the people which cause them to select themselves in the group create abnormal or undesirable conditions in the group....
 samples. That is, the only people included in the studies were those who reported their experiences to the experimenter. Simner et al. conducted the first random population study, arriving at a prevalence of 1 in 23. Recent data suggests that grapheme ? color, and days of the week ? color variants are most common.

Almost every study that has investigated the topic has suggested that synesthesia clusters within families, consistent with a genetic origin for the condition. The earliest references to the familial component of synesthesia date to the 1880s, when Francis Galton
Francis Galton

Sir Francis Galton Fellow of the Royal Society , Cousin#Half_cousins of Charles Darwin, was an England Victorian era polymath, anthropologist, Eugenics, tropical List of explorers, geographer, inventor, meteorologist, proto-geneticist, Psychometrics, and statistician....
 first described the condition in Nature
Nature (journal)

Nature is a prominent scientific journal, first published on 4 November 1869. Although most scientific journals are now highly specialized, Nature is one of the few journals, along with other weekly journals such as Science and Proceedings of the National Academy of Sciences, that still publishes original research articles ac...
. Since then, other studies have supported this conclusion. However, early studies which claimed a much higher prevalence in women than in men (up to 6:1) most likely suffered from a sampling bias
Biased sample

A biased sample is a sample of a statistical population in which some members of the population are less likely to be included than others. If the bias makes estimation of population parameters impossible, the sample is a non-probability sample....
 due to the fact that women are more likely to self-disclose than men. More recent studies, using random samples find a sex ratio of 1.1:1.

Until early 2009, the observed patterns of inheritance were thought to be consistent with an X-linked
Sex linkage

Sex linkage is the phenotype expression of an allele that is related to the chromosomal sex of the individual. This mode of inheritance is in contrast to the inheritance of traits on autosome chromosomes, where both sexes have the same probability of expressing the trait....
 mode of inheritance because there had been no verified reports of father-to-son transmission, and other forms of transmission (father-to-daughter, mother-to-son and mother-to-daughter) had been reported much more commonly. However, the first genome-wide association study
Genome-wide association study

In genetic epidemiology, a genome-wide association study - also known as whole genome association study - is an examination of genetic variation across a given genome, designed to identify genetic associations with observable traits....
 (GWAS) of synesthesia failed to find any evidence of X-linkage, and additionally reported two verified cases of father-to-son transmission. The GWAS suggests that synesthesia may depend on interactions between several genes, including genetic loci associated with synesthesia on the long arm of chromosome 2
Chromosome 2 (human)

Chromosome 2 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 2 is the second largest human chromosome, spanning more than 237 million base pairs and representing almost 8% of the total DNA in cell ....
 (2q24), the long arm of chromosome 5
Chromosome 5 (human)

Chromosome 5 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 5 spans about 181 million base pairs and represents almost 6% of the total DNA in cell ....
 (5q33), the short arm of chromosome 6
Chromosome 6 (human)

Chromosome 6 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 6 spans more than 170 million base pairs and represents between 5.5 and 6% of the total DNA in cell ....
 (6p12) and the short arm of chromosome 12
Chromosome 12 (human)

File:Chromosome_12.svgChromosome 12 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 12 spans about 143 million base pairs and represents between 4 and 4.5 percent of the total DNA in cell ....
 (12p12). There was no evidence of an association between synesthesia and the X chromosome
X chromosome

The X chromosome is one of the two sex determination system chromosomes in many animal species, including mammals . It is a part of the XY sex-determination system and X0 sex-determination system....
.

Additionally, pairs of identical twins have been identified where only one member of the pair experiences synesthesia and it has been noted that synesthesia can skip generations within a family, consistent with models of incomplete penetrance
Penetrance

Penetrance is a term used in genetics describing the proportion of individuals carrying a particular variation of a gene that also express an associated trait ....
. Ward and Simner also note that it is quite common for synesthetes within a family to experience different types of synesthesia, suggesting that the gene or genes involved in synesthesia do not lead to specific types of synesthesia. Rather developmental factors such as gene expression
Gene expression

Gene expression is the process by which inheritable information from a gene, such as the DNA sequence, is made into a functional gene product, such as protein or RNA....
 and environment must also play a role in determining which types of synesthesia an individual synesthete will experience.

Objective verification

Synaesthesiatest
Proof that someone is a synesthete is easy to come by, and hard to "fake." The simplest test involves test-retest reliability over long periods of time. Synesthetes consistently score higher on such tests than non-synesthetes (either with color names, color chips or even a color picker providing up to 16.7 million color choices). Synesthetes may score as high as 90% consistent over test-retest intervals of up to one year, while non-synesthetes will score 30-40% consistent over test-retest intervals of only one month, even if warned that they will be retested (e.g., ).

More specialized tests include using modified versions of the Stroop effect
Stroop effect

In psychology, the Stroop effect is a demonstration of the reaction time of a task. When a word such as blue, green, red, etc. is printed in a color differing from the color expressed by the word's semantic meaning , naming the color of the word takes longer and is more prone to errors than when the meaning of the word is congruent with its i...
. In the standard Stroop paradigm, it is harder to name the ink color of the word "red" when it is printed in blue ink than if it is presented in red ink. This demonstrates that reading is automatic
Automaticity

Automaticity is the ability to do things without occupying the mind with the low level details required. It is usually the result of learning, repetition , and practice....
. Similarly, if a grapheme ? color synesthete is presented with the digit 4 that he or she experiences as red in blue ink, he or she is slower to identify the ink color. This is not because the synesthete cannot see the blue ink, but rather because the same sort of "response conflict" that is responsible for the standard Stroop effect is also occurring between the color of the ink and the automatically induced color of the grapheme. This response conflict is strongest if the color of the ink is the opponent color
Opponent process

The color opponent process is a color theory that states that the human visual system interprets information about color by processing signals from cone cell and rod cell in an antagonistic manner....
 to the synesthetically associated color (e.g., red vs. green), indicating that the perception of synesthetic colors relies on the same mechanisms as the perception of real colors. Similar variants of the Stroop effect can be devised where, for example, a music ? color synesthete is asked to name a red color patch while listening to a tone that produces a blue sensation, or where a musical key ? taste synesthete is asked to identify a bitter taste while hearing a musical interval that induces a sweet taste.

Finally, studies of grapheme ? color synesthesia have demonstrated that synesthetic colors can improve performance on certain visual tasks, at least for some synesthetes. Inspired by tests for color blindness
Color blindness

Color blindness, a color vision deficiency, is the inability to perceive differences between some of the colors that others can distinguish. It is most often of genetic nature, but may also occur because of eye, nerve, or brain damage, or due to exposure to certain chemicals....
, Ramachandran and Hubbard presented synesthetes and non-synesthetes with displays composed of a number of 5s, with some 2s embedded among the 5s. These 2s could make up one of four shapes; square, diamond, rectangle or triangle. For a synesthete who sees 2s as red and 5s as green, their synesthetic colors help them to find the "embedded figure". Subsequent studies have explored these effects more carefully, and have found that 1) there is substantial variability among synesthetes and 2) while synesthesia is evoked early in perceptual processing, it does not occur prior to attention
Attention

Attention is the cognitive process of selectively concentrating on one aspect of the environment while ignoring other things. Examples include listening carefully to what someone is saying while ignoring other conversations in a room or listening to a cell phone conversation while driving a car....
 (e.g.,).

Possible neural basis


Synaesthesiabrain
Theories of the neural basis of synesthesia start from the observation that there are dedicated regions of the brain that are specialized for certain functions. Based on this notion of specialized regions, some researchers have suggested that increased cross-talk between different regions specialized for different functions may account for different types of synesthesia. For example, since regions involved in the identification of letters and numbers lie adjacent to a region involved in color processing (V4), the additional experience of seeing colors when looking at graphemes might be due to "cross-activation" of V4. This cross-activation may arise due to a failure of the normal developmental process
Neural development

The study of neural development draws on both neuroscience and developmental biology to describe the cellular and molecular mechanisms by which complex nervous systems emerge during morphogenesis and throughout life....
 of pruning.

Alternatively, synesthesia may arise through "disinhibited feedback" or a reduction in the amount of inhibition along feedback pathways. Normally, the balance of excitation and inhibition are maintained. However, if normal feedback were not adequately inhibited, then signals coming from later multi-sensory stages of processing might influence earlier stages of processing, such that tones would activate visual cortical areas in synesthetes more than in non-synesthetes. In this case, it might explain why some users of psychedelic drugs
Psychedelics, dissociatives and deliriants

The general group of pharmacology agents commonly known as hallucinogens can be divided into three broad categories: Psychedelic drugs, dissociatives, and deliriants....
 such as LSD
LSD

Lysergic acid diethylamide, LSD, LSD-25, or acid, is a semisynthetic psychedelic drug of the ergoline family. Its unusual psychological effects, which include visuals of colored patterns behind the eyes in the mind, a sense of time distorting, and crawling geometric patterns, have made it one of the most widely known psyched...
 or mescaline
Mescaline

Mescaline or 3,4,5-trimethoxyphenethylamine is a naturally-occurring psychedelic alkaloid of the phenethylamine class. It is mainly used as a recreational drug, an entheogen, and a tool to supplement various practices for transcendence , including in meditation, psychonautics, art projects, and psychedelic psychotherapy....
 report synesthetic experiences while under the influence of the drug.

Functional neuroimaging
Functional neuroimaging

Functional neuroimaging is the use of neuroimaging technology to measure an aspect of brain function, often with a view to understanding the relationship between activity in certain brain areas and specific mental functions....
 studies using positron emission tomography
Positron emission tomography

Positron emission tomography is a nuclear medicine medical imaging technique which produces a three-dimensional image or picture of functional processes in the body....
 (PET) and functional magnetic resonance imaging
Functional magnetic resonance imaging

Functional MRI or functional Magnetic Resonance Imaging is a type of specialized MRI scan. It measures the haemodynamic response related to neuron activity in the brain or spinal cord of humans or other animals....
 (fMRI) have demonstrated significant differences between the brains of synesthetes and non-synesthetes. Recent studies using fMRI have demonstrated that V4 is more active in both word ? color and grapheme ? color synesthetes. Using diffusion tensor imaging (DTI), a technique which allows the visualization of white matter
White matter

White matter is one of the three main solid components of the central nervous system. White matter tissue of the freshly cut brain appears white to the naked eye because of being composed largely of lipid....
 fiber pathways in the intact human brain, Rouw and Scholte have demonstrated increased connectivity in regions of the fusiform gyrus
Fusiform gyrus

The fusiform gyrus is part of the temporal lobe. It is also known as the occipitotemporal gyrus. Other sources have the fusiform gyrus above the occipitotemporal gyrus and underneath the parahippocampal gyrus....
, intraparietal sulcus
Intraparietal sulcus

The intraparietal sulcus is located on the lateral surface of the parietal lobe, and consists of an oblique and a horizontal portion. The IPS contains a series of functionally distinct subregions that have been intensively investigated using both single cell neurophysiology in primates and human functional neuroimaging....
 and frontal cortex. In addition, they showed that the degree of white matter connectivity in the fusiform gyrus correlates with the intensity of the synesthetic experience, suggesting that these anatomical differences are the origin of the synesthetic experience.

Associated cognitive traits

Very little is known about the overall cognitive traits associated with synesthesia (or, indeed if there are any cognitive traits that are consistently associated with synesthesia). Some studies have suggested that synesthetes are unusually sensitive to external stimuli. Other possible associated cognitive traits include left-right confusion, difficulties with mathematics
Dyscalculia

Dyscalculia or math disability is a specific learning disability involving innate difficulty in learning or comprehending mathematics....
, and difficulties with writing
Dysgraphia

Dysgraphia is a deficiency in the ability to writing, regardless of the ability to Reading , not due to intellectual impairment.People with dysgraphia usually can write on some level, but often lack motor coordination, and may find other fine motor skill tasks such as tying shoes difficult....
.

However, synesthetes may be more likely to participate in creative activities, and some studies have suggested a correlation between synesthesia and creativity
Creativity

Creativity is a mental and social process involving the generation of new ideas or concepts, or new associations of the creative mind between existing ideas or concepts....
. Other research has suggested that synesthesia may contribute to superior memory abilities. However, it is unclear whether this is a general feature of synesthesia or whether it is true of only a small minority. Interviews with synesthetes show that some use their synesthetic abilities for creative purposes or as a general orientation in life, while other who have been tested positively do not use it. Individual development of perceptual, cognitive skills and the social environment in which synesthetes are raised and work probably determine the variety in awareness and practical use of synesthetic abilities. These are major topics of current and future research.

Links with other areas of study

Researchers study synesthesia not only because it is inherently interesting, but also because they hope that studying synesthesia will offer new insights into other questions, such as how the brain combines information from different sensory modalities, referred to as crossmodal
Crossmodal

Crossmodal perception relates to different sensory modalities, including synesthesia and sensory substitution.Crossmodal perception, crossmodal integration and crossmodal Neuroplasticity of the human brain are increasingly studied in neuroscience to gain a better understanding of the...
 perception and multisensory integration.

One example of this is the bouba/kiki effect
Bouba/kiki effect

The Bouba/Kiki Effect was discovered by German-American psychologist Wolfgang K?hler in 1929. In psychological experiments, first conducted on the island of Tenerife, K?hler showed forms similar to those shown at the right, and found a strong preference to pair the jagged shape with the word "takete" and the rounded shape with the word "balu...
. In a psychological experiment first designed by Wolfgang Köhler
Wolfgang Köhler

Wolfgang K?hler was a German psychologist who, with Max Wertheimer and Kurt Koffka, founded Gestalt psychology....
, people are asked to choose which of two shapes (pictured right) is named bouba and which is named kiki. 95% to 98% of people choose kiki for the angular shape and bouba for the rounded shape. With individuals on the island of Tenerife
Tenerife

Tenerife, a Spain island, is the largest of the seven Canary Islands in the Atlantic Ocean off the coast of Africa. Tenerife has an area of 2034.38 square kilometers, and 886,033 inhabitants, which make it the most populated island of the Canary Islands and Spain....
, Köhler showed a similar preference between shapes called "takete" and "maluma". Recent work by Daphne Maurer and colleagues has shown that even children as young as 2.5 years old (too young to read) show this effect.

Ramachandran and Hubbard suggest that the kiki/bouba effect has implications for the evolution of language, because it suggests that the naming of objects is not completely arbitrary. The rounded shape may most commonly be named bouba because the mouth makes a more rounded shape to produce that sound while a more taut, angular mouth shape is needed to make the sound kiki. The sounds of a K are harder and more forceful than those of a B, as well. The presence of these "synesthesia-like mappings" suggest that this effect might be the neurological basis for sound symbolism
Sound symbolism

Sound symbolism or phonosemantics is a branch of linguistics and refers to the idea that vocal sounds have meaning. In particular, sound symbolism is the idea that phonemes carry meaning in and of themselves....
, in which sounds are non-arbitrarily mapped to objects and events in the world.

Similarly, synesthesia researchers hope that, because of their unusual conscious experiences, the study of synesthesia will provide a window into better understanding consciousness
Consciousness

Consciousness is a difficult term to define, because the word is used and understood in a wide variety of ways, so that it frequently happens that what one person sees as a definition of consciousness is seen by others as about something else altogether....
 and in particular on the neural correlate
Neural correlate

A neural correlate of a experience is any bodily component, such as an electro-neuro-biological state or the state assumed by some biophysics subsystem of the brain, whose presence necessarily and regularly correlates with such a specific content of experience....
s of consciousness, or what the brain mechanisms that allow us to be conscious might be. In particular, some researchers have argued that synesthesia is relevant to the philosophical
Philosophy

Philosophy is the study of general problems concerning matters such as existence, knowledge, truth, beauty, justice, validity, mind, and language....
 problem of qualia
Qualia

The plural word 'Qualia' , singular 'quale' , from the Latin for ?what sort? or ?what kind?, is a term of art used in philosophy for sensory occurrences of all kinds....
, since synesthetes experience additional qualia evoked through non-typical routes.

Artistic investigations

Steenvision


The phrase synesthesia in art has historically referred to a wide variety of artistic experiments that have explored the co-operation of the senses (e.g. seeing and hearing) in the genres of visual music
Visual music

Visual music, sometimes called "colour music", refers to the use of musical structures in visual imagery, which can also include silent films or silent Lumia work....
, music visualization
Music visualization

Music visualization, a feature found in some media player software, generates animated Computer-generated imagery based on a piece of recorded music....
, audiovisual art
Audiovisual art

The exploration of kinetic abstract art and music set in relation to each other.Visual music, Lumia, abstract film, audiovisual performances and Installation art....
, abstract film
Abstract film

Abstract film is a subgenre of experimental film. Its history often overlaps with the concerns and history of visual music. Some of the earliest abstract motion pictures known to survive are those produced by a group of German artists working in the early 1920s, a movement referred to as "Absolute" Film: Walter Ruttmann, Hans Richter , Viking...
, and intermedia
Intermedia

Intermedia was a concept employed in the mid-sixties by Fluxus artist Dick Higgins to describe the ineffable, often confusing, inter-disciplinary activities that occur between genres that became prevalent in the 1960s....
.

The age-old artistic views on synesthesia have some overlap with the current neuroscientific view on neurological synesthesia, but also some major differences, e.g. in the contexts of investigations, types of synesthesia selected, and definitions. While in a neuroscientific studies synesthesia is defined as the elicitation of perceptual experiences in the absence of the normal sensory stimulation, in the arts the concept of synaesthesia in the arts is more often defined as the simultaneous perception of two or more stimuli as one gestalt experience. The usage of the term synesthesia in art should, therefore, be differentiated from neurological synesthesia in scientific research. Synesthesia is by no means unique to artists or musicians. Only in the last decades scientific methods have become available to assess synesthesia in persons. For synesthesia in artists before that time one has to interpret (auto)biographical information.

Synesthetic art may refer to either art created by synesthetes or art created to convey the synesthetic experience. It is an attempt to understand the relation between the experiences of congenital synesthetes, the experiences of non-synesthetes, and an appreciation of such art by both synesthetes and non-synesthetes. These distinctions are not mutually exclusive, as, for example, art by a synesthete might also evoke synesthesia-like experiences in the viewer. However, it should not be assumed that all "synesthetic" art accurately reflects the synesthetic experience. This latter category is also sometimes referred to as artificial synesthesia.

Historically, synesthetic art consisted of a number of contrivances, such as color organs, musical painting and more recently, visual music, all of which have been intended to evoke cross-sensory fusions in the audience, although the inventors of such artifices were not necessarily synesthetes themselves, and may not even have been aware of synesthesia as such. Numerous modern synesthete artists, including Carol Steen, Marcia Smilack, and others have described in detail the manner in which they use their synesthesia in the creation of their artworks, demonstrating the complex interplay between their personal experiences and their artistic creations.

Synesthesia has been a source of inspiration for artists (e.g. Van Gogh, Kandinsky, Mondrian
Piet Mondrian

Pieter Cornelis Mondriaan, after 1912 Mondrian, , was a Dutch people Painting.He was an important contributor to the De Stijl art movement and group, which was founded by Theo van Doesburg....
), composers (e.g. Scriabin, Messiaen, Ligeti
Ligeti

Ligeti is a surname, and may refer to:...
), poets and novelists (e.g. Baudelaire, Nabokov
Vladimir Nabokov

Vladimir Vladimirovich Nabokov was a Multilingualism Russian-American novelist and short story writer.Nabokov wrote his first nine novels in Russian language, then rose to international prominence as a master English prose stylist....
) and contemporary digital artists. Kandinsky and Mondrian experimented with image-music correspondences in their paintings. Scriabin composed symphonic poems of sound and color. Messiaen captured the colors of landscapes in music. Baudelaire used synesthesia as a paradigm for symbolist literature. New movements in art (like literary symbolism, non-figurative art and visual music) have profited from artists experimentations with synesthetic perceptions. Synesthetic art forms have contributed to the awareness of synesthetic and multisensensory ways of perceiving in the general public.

Literary depictions


In addition to its role in art, synesthesia has often been used as a plot device or as a way of developing a particular character's internal states. In order to better understand the influence of synesthesia in popular culture, and how the condition is viewed by non-synesthetes, it is informative to examine books in which one of the main characters is portrayed as experiencing synesthesia. In addition to these fictional portrayals, the way in which synesthesia is presented in non-fiction books to non-specialist audiences is instructive. Author and synesthete, Patricia Lynne Duffy
Patricia Lynne Duffy

Patricia Lynne Duffy is an instructor in the UN Language and Communications Programme. She has an M.A. from Teachers College, Columbia University....
 has described four ways in which synesthete characters have been used in modern fiction.
  1. Synesthesia as Romantic
    Romanticism

    Romanticism is a complex artistic, literary, and intellectual movement that originated in the second half of the 18th century in Western Europe, and gained strength during the Industrial Revolution....
     ideal: in which the synesthetic experience illustrates the Romantic ideal of transcending our experience of the world. Books in this category include The Gift by Vladimir Nabokov
    Vladimir Nabokov

    Vladimir Vladimirovich Nabokov was a Multilingualism Russian-American novelist and short story writer.Nabokov wrote his first nine novels in Russian language, then rose to international prominence as a master English prose stylist....
    .
  2. Synesthesia as pathology: in which synesthesia is portrayed as pathological. Books in this category include The Whole World Over by Julia Glass.
  3. Synesthesia as Romantic pathology: in which synesthesia is portrayed as pathological, but also as providing an avenue into the Romantic ideal of transcending normal experience. Duffy selects Holly Payne’s novel, The Sound of Blue as an example of this category.
  4. Synesthesia as health and balance for some individuals: in which synesthesia is portrayed as indicating psychological health and well being. In particular, Duffy selects two novels, Painting Ruby Tuesday by Jane Yardley
    Jane Yardley

    Jane Yardley is an English author, raised in a village in 1960s Essex, . She went to university in London and gained a Doctor of Philosophy degree from Charing Cross Hospital Medical School....
     and A Mango-Shaped Space by Wendy Mass to illustrate this usage of synesthesia as a plot or character device.


Note that not all of the depictions of synesthesia in the fictional works are accurate. Some are highly inaccurate and reflect more about the author's interpretation of synesthesia than about the phenomenon itself.

In Mary Shelley
Mary Shelley

Mary Shelley was a British novelist, short story writer, dramatist, essayist, biographer, and travel literature, best known for her Gothic fiction Frankenstein ....
's Frankenstein
Frankenstein

Frankenstein; or, The Modern Prometheus, generally known as Frankenstein, is a novel written by the British author Mary Shelley. Shelley started writing Frankenstein when she was 18 and finished when she was 19....
, the creature describes himself as being in a synesthetic state early in his existence even though the phenomenon was not well-documented when the book was written.

People with synesthesia


There is a great deal of debate about whether or not synesthesia can be identified through historical sources. A small number of famous people have been labeled as synesthetes on the basis of at least two historical sources. This includes individuals of many different talents, such as artists, novelists, composers, musicians, and scientists. For more details, and supporting evidence, see the main list of people with synesthesia.

Artists with synesthesia include the painter David Hockney
David Hockney

David Hockney, Order of the Companions of Honour, Royal Academician, is an English painter, draughtsman, printmaker, stage designer and photographer, based in Yorkshire, United Kingdom, although he also maintains a base in London....
, who perceives music synesthetically as colors, and who used these synesthetic colors when painting stage sets, but not in creating his other artworks. Also, Russian painter Wassily Kandinsky
Wassily Kandinsky

Wassily Wassilyevich Kandinsky was a Russian Painting, printmaker and art theorist. One of the most famous 20th-century artists, he is credited with painting the first modern abstract art works....
 had the same type of synesthesia (sound and color). Perhaps the most famous synesthete author was Vladimir Nabokov
Vladimir Nabokov

Vladimir Vladimirovich Nabokov was a Multilingualism Russian-American novelist and short story writer.Nabokov wrote his first nine novels in Russian language, then rose to international prominence as a master English prose stylist....
, who had grapheme ? color synesthesia, one of the most common types, which he described at length in his autobiography, Speak Memory, and which he sometimes portrays in giving his characters synesthesia. Composers include Duke Ellington
Duke Ellington

Edward Kennedy "Duke" Ellington was an American composer, pianist, and bandleader.Duke Ellington was recognized during his life as one of the most influential Jazz royalty, if not in all American music and he is of only four jazz musicians ever to have been featured on the cover of Time magazine ....
 (timbre ? color), Franz Liszt
Franz Liszt

Franz Liszt was a Kingdom of Hungary composer, virtuoso pianist and teacher.Liszt became renowned throughout Europe for his great skill as a performer during the 19th century....
 (music ? color), Nikolai Rimsky-Korsakov
Nikolai Rimsky-Korsakov

Nikolai Andreyevich Rimsky-Korsakov , also Nikolay, Nicolai, and Rimsky-Korsakoff, was a Russian composer, and a member of the group of composers known as "The Five." Noted particularly for a predilection for folk and fairy-tale subjects as well as his extraordinary skill in orchestration, his best known orchestral compositions...
, and Olivier Messiaen
Olivier Messiaen

Olivier Messiaen was a French composer, organ , and ornithology. He entered the Conservatoire de Paris at the age of 11 and numbered Paul Dukas, Maurice Emmanuel, Charles-Marie Widor and Marcel Dupr? among his teachers....
, who had a complex form of synesthesia in which chord structures produced synesthetic colors. Notable synesthete scientists include Richard Feynman
Richard Feynman

Richard Phillips Feynman was an United States physicist known for the path integral formulation of quantum mechanics, the theory of quantum electrodynamics and the physics of the superfluidity of supercooled liquid helium, as well as work in particle physics ....
. Feynman describes in his autobiography, What Do You Care What Other People Think?, that he had the grapheme ? color type. The European record-holder for number of digits of pi
Pi

Pi or p is a mathematical constant whose value is the ratio of any circle's circumference to its diameter in Euclidean geometry; this is the same value as the ratio of a circle's area to the square of its radius....
 recited, Daniel Tammet
Daniel Tammet

Daniel Paul Tammet is a British high-functioning autism autistic savant gifted with a facility for mathematics and natural language learning. He was born Daniel Corney , the first of nine children, to working-class parents in London....
, has synesthesia, and claims to use his ability to "see" and experience numbers as spatial objects, textures and tones to perform advanced mathematical calculations in his head. Other notable synesthetes include musicians John Mayer and Patrick Stump
Patrick Stump

Patrick Martin Stumph was born on April 27, 1984, in Glenview, Illinois. He is an American musician, composer, record producer and music critic....
; actress Stephanie Carswell
Stephanie Carswell

Stephanie Carswell is an Australian-born actress and lyric soprano, with a vocal range of over 3? octaves. Also credited as Stephanie-May Carswell / Lottie May....
; and electronic musician Aphex Twin
Aphex Twin

Richard David James , aka Aphex Twin, is an electronic musician who has been described as "the most inventive and influential figure in contemporary electronic music." He founded the record label Rephlex Records in 1991 with friend Grant Wilson-Claridge....
, who claims to be inspired by lucid dreams
Lucid Dreams

For the psychological phenomenon, see lucid dream."Lucid Dreams" is a single from the Scotland band Franz Ferdinand , appearing on their latest album Tonight: Franz Ferdinand....
 as well as synesthesia (music ? color). The classical pianist Hélène Grimaud
Hélène Grimaud

H?l?ne Grimaud is a France pianist.She was born in Aix-en-Provence, France. She is descended from Sephardi Jews from Corsica on her mother's side and from Berber Jews on her father's side....
 has the condition as well. Although this has not been verified, Pharrell Williams
Pharrell Williams

Pharrell Williams , commonly known as Pharrell, is an American record producer, singer-songwriter, and rapper. He, along with Chad Hugo are the duo of The Neptunes where they produce pop music, hip hop music and rhythm and blues music....
 of the hip-hop production group The Neptunes
The Neptunes

The Neptunes is the name for the record production duo consisting of Pharrell Williams and Chad Hugo who created the sound for some very successful hip hop music, R&B and Pop music artists in the late-90s and 2000s....
 and band N.E.R.D. claims to experience synesthesia, and used this concept as the basis of the N.E.R.D. album Seeing Sounds
Seeing Sounds

Seeing Sounds is the third studio album by American hip hop music, rock music, funk band N.E.R.D released on June 6, 2008, through Star Trak Entertainment and Interscope Records....
.

Some of the most frequently mentioned artists in connection with synesthesia probably were not synesthetes. Analyzing compositions such as Prometheus: The Poem of Fire
Prometheus: Poem of Fire

Prometheus: Poem of Fire, Opus 60 , is a symphonic work by Russian composer Alexander Scriabin for piano, orchestra, voice, and clavier ? lumi?res, entitled "Chromola", a Color organ invented by Preston Millar....
 and Mysterium
Mysterium (Scriabin)

Mysterium is an unfinished musical work by composer Alexander Scriabin. He started working on the composition in 1903, but it was incomplete at the time of his death in 1915....
, some researchers argue that the Russian composer Alexander Scriabin
Alexander Scriabin

Alexander Nikolayevich Scriabin was a Russian composer and pianist who initially developed a highly lyrical and idiosyncratic tonal language inspired by the music of Chopin....
 was most likely not a synesthete. The synesthetic motifs found in Scriabin's compositions – most noticeably in Prometheus, composed in 1911 – are developed from ideas from Isaac Newton
Isaac Newton

Sir Isaac Newton, Fellow of the Royal Society was an English people physicist, mathematician, Astronomy, Natural philosophy, Alchemy, and Theology and one of the the 100 in human history....
, and follow a circle of fifths
Circle of fifths

In music theory, the circle of fifths shows the relationships among the twelve tones of the chromatic scale, their corresponding key signatures, and the associated major and minor keys....
. Others have argued that Scriabin, besides his personal synesthetic perceptions, had developed a universal system that associated colors to musical keys, which was based on the literature and meant for public performances. As an artist, he was particularly interested in the psychological effects on the audience when they experienced sound and color simultaneously. His theory was that when the correct color was perceived with the correct sound, ‘a powerful psychological resonator for the listener’ would be created. On the score of Prometheus Scriabin wrote next to the instruments separate parts for the color organ
Color organ

The term color organ refers to a tradition of mechanical , then electromechanical, devices built to represent sound or to accompany music in a visual medium—by any number of means....
.

The French Romantic
Romanticism

Romanticism is a complex artistic, literary, and intellectual movement that originated in the second half of the 18th century in Western Europe, and gained strength during the Industrial Revolution....
 poets Arthur Rimbaud
Arthur Rimbaud

Jean Nicolas Arthur Rimbaud was a French people poet, born in Charleville-M?zi?res. As part of the decadent movement, his influence on modern literature, music and art has been enduring and pervasive....
 and Charles Baudelaire
Charles Baudelaire

Charles Pierre Baudelaire was a nineteenth century French poetry, critic and translator. A controversial figure in his lifetime, Baudelaire's name has become a byword for literary and artistic Decadent movement....
 wrote poems which focused on synesthetic experience, but were evidently not synesthetes themselves. Baudelaire's (1857) () introduced the Romantic notion that the senses can and should intermingle. Baudelaire participated in an experiment with hashish by the French psychiatrist Jacques-Joseph Moreau
Jacques-Joseph Moreau

Dr. Jacques-Joseph Moreau was a French psychiatrist and member of the Club des Hashischins. Moreau was the first physician to do systematic work on psychoactive drug' effects on the central nervous system, and to catalogue, analyze, and record his observations....
 and became interested in how the senses correspond in perception. Rimbaud, following Baudelaire, wrote Voyelles (1871) () which was perhaps more important than in popularizing synesthesia, although he later admitted "J'inventais la couleur des voyelles!" [I invented the colors of the vowels!].

, a synesthete, and the President of the American Synesthesia Association
American Synesthesia Association

The American Synesthesia Association is a not-for-profit academic and public society whose mission is to foster and promote the education and the advancement of knowledge of the phenomena of synesthesia, a neurological condition in which stimulation in one sensory modality leads to experiences in a second, unstimulated modality....
, maintains a list of people with synesthesia, "pseudosynesthetes," and individuals who are most likely not synesthetic, but who used synesthesia in their art or music.

Further reading

  • Baron-Cohen, S.
    Simon Baron-Cohen

    Simon Baron-Cohen is Professor of Developmental Psychopathology in the Departments of Psychiatry and Experimental Psychology, a Fellow of Trinity College, Cambridge, and Director of the Autism Research Centre at the University of Cambridge, in the United Kingdom....
     and Harrison, J. (Eds., 1997). Synaesthesia: Classic and Contemporary Readings. Oxford: Blackwell Publishers. ISBN 0-631-19764-8.
  • Campen, Cretien van
    Cretien van Campen

    Cretien van Campen is an author, editor and scientific researcher in social science and fine arts. He is the founder of Synesthetics Netherlands and is affiliated with the Netherlands Institute for Social Research....
    . (2007) Cambridge, MA: MIT Press/Leonardo Books. ISBN 0-262-22081-4
  • Cytowic, R. (2003). The Man Who Tasted Shapes. New York: Tarcher/Putman. ISBN 0-262-53255-7.
  • Dann, K. (1998). Bright Colors Falsely Seen. Cambridge: Harvard University Press. ISBN 0-300-06619-8.
  • Duffy, P. L.
    Patricia Lynne Duffy

    Patricia Lynne Duffy is an instructor in the UN Language and Communications Programme. She has an M.A. from Teachers College, Columbia University....
     (2001). Blue Cats and Chartreuse Kittens: How Synesthetes Color their Worlds. New York: Henry Holt & Company. ISBN 0-7167-4088-5.
  • Harrison, J. (2001). Synaesthesia: The Strangest Thing. Oxford: Oxford University Press. ISBN 0-19-263245-0.
  • Robertson, L. and Sagiv, N. (Eds., 2005). Synesthesia: Perspectives from Cognitive Neuroscience. Oxford: Oxford University Press. ISBN 0-19-516623-X.
  • Tammet, D.
    Daniel Tammet

    Daniel Paul Tammet is a British high-functioning autism autistic savant gifted with a facility for mathematics and natural language learning. He was born Daniel Corney , the first of nine children, to working-class parents in London....
     (2006) Born on a Blue Day: A Memoir of Aspergers and an Extraordinary Mind. Hodder & Stoughton Ltd. ISBN 978-0-34-089974-8.
  • Mass, W.
    Wendy Mass

    Wendy Mass is an award winning author of children's books. Her most successful book was A Mango Shaped Space which won The Schneider Family Book Award in 2003....
     (2003) A Mango-Shaped Space. Little, Brown and Company. ISBN 0-316-52388-7
  • Jamie Ward (2008) The Frog who croaked Blue: Synesthesia and the Mixing of the Senses. Routledge. ISBN 978-0-415-43014-2.


See also


External links


Synesthesia associations

  • (in German)


Community sites

  • A forum for synesthetes and people interested in synesthesia, with a special section for teenage synesthetes.
  • compiled by Cretien van Campen
    Cretien van Campen

    Cretien van Campen is an author, editor and scientific researcher in social science and fine arts. He is the founder of Synesthetics Netherlands and is affiliated with the Netherlands Institute for Social Research....
     for Leonardo/ISAST
  • by Patricia Lynne Duffy
    Patricia Lynne Duffy

    Patricia Lynne Duffy is an instructor in the UN Language and Communications Programme. She has an M.A. from Teachers College, Columbia University....


Scientific resources

  • take the tests to discover if you are synesthetic. Developed by David Eagleman
    David Eagleman

    David Eagleman is a neuroscientist at Baylor College of Medicine, where he directs the Laboratory for Perception and Action and the Initiative on Neuroscience and Law....
    .
  • Downloads and information.
  • Synesthesia research including pdf versions of scientific articles.
  • by Cretien van Campen
    Cretien van Campen

    Cretien van Campen is an author, editor and scientific researcher in social science and fine arts. He is the founder of Synesthetics Netherlands and is affiliated with the Netherlands Institute for Social Research....
     Info on artistic and scientific experiments with synesthesia, gives the historical background.
  • Synaesthesia researcher, based in the UK, useful information and links to articles.
  • a research project at the University of Cambridge investigating the effects of grapheme-colour synesthesia on numerical processing in children.
  • , a synesthesia portal by Dr. Hugo Heyrman, more specific on the interaction between art and synesthesia.
  • , Homepage about Synaesthesia (English/Deutsch) by Marc Jacques Mächler


Scientific articles on the web

  • Scientific American
    Scientific American

    Scientific American is a popular science science magazine, published since August 28, 1845, making it one of the oldest continuously published magazines in the United States....
     article () by Vilayanur S. Ramachandran
    Vilayanur S. Ramachandran

    Vilayanur S. "Rama" Ramachandran is a neurology best known for his work in the fields of behavioral neurology and psychophysics. He is currently the Director of the Center for Brain and Cognition, Professor in the Psychology Department and Neurosciences Program at the University of California, San Diego, and Adjunct Professor of Biology at th...
     and Edward M. Hubbard, May 2003.
  • The neuroscience journal Cortex presents a special issue focusing on modern scientific research of synesthesia.
  • Campen, Cretien van
    Cretien van Campen

    Cretien van Campen is an author, editor and scientific researcher in social science and fine arts. He is the founder of Synesthetics Netherlands and is affiliated with the Netherlands Institute for Social Research....
     (2009), , TECCOGS , vol. 1, pp. 1-13.


Popular press

  • New York Times article on lexical-gustatory synesthesia. November 22, 2006. New York Times.
  • World Science's article on hearing colours. Sept. 7, 2006. Courtesy University College London and World Science staff
  • on ABC Primetime
    Primetime (TV series)

    Primetime is a general-interest United Statesn news magazine show which debuted on American Broadcasting Company in 1989 with co-hosts Sam Donaldson and Diane Sawyer and originally had the title Primetime Live....
    . 15 August 2006
  • at BBC News
    BBC News

    BBC News, formerly BBC News and Current Affairs, is the department within the BBC responsible for the corporation's news-gathering and production of news programmes on BBC television, radio and online....
    , 24 March 2005
  • Synesthesia may occur as a visual migraine aura.
  • , Experiencing Justin Lassen
    Justin Lassen

    Justin Lassen, born August 27, 1981 in Denver, Colorado, is a renowned composer, producer, multi-instrumentalist and remixer who has worked in the film and game industries....
    's World, Feature on CGSociety (May 2006).
  • Live Science, 17 June 2007, by Charles Q. Choi.
  • – words triggering taste sensations (Cosmos Magazine, 23 November 2006)