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| + | '''Synesthesia''' (also spelled '''synæsthesia''' or '''synaesthesia''') - from the Greek ''syn''- meaning ''union'' and ''aesthesis'' meaning ''sensation'', is a neurological condition in which two or more bodily [[sense]]s are coupled. For example, in a form of synaesthesia known as grapheme-color synaesthesia, letters or numbers may be perceived as inherently colored. In other forms of synesthesia, musical and other sounds may be perceived as colored or having particular shapes. While cross-sensory [[metaphor]]s are sometimes described as "synesthetic", true neurological synesthesia is involuntary and occurrs in about four percent of the population (1 in 23 persons) across its range of variants (see Simner et al., in press). It runs strongly in families, possibly inherited as an X-linked dominant trait. |
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| + | Markus Zedler describes in [http://synesthesia.info/abstracts.html a brief article] synesthesia as "a perceptual condition in which the stimulation in one sensory modality elicits a concurrent sensation in another, a perception which is perceived as real." |
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| − | {{otheruses}} |
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| ⚫ | [[Image:BoobaKiki.png|thumb|right|250px|Booba and Kiki shapes|This picture is used as a test to demonstrate that people may not attach sounds to shapes arbitrarily: A remote tribe calls one of these shapes '''Booba''' and the other '''Kiki.''' Decide which is which and then click the image to check your answer.]] |
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| − | '''Synaesthesia''' (also spelled synæsthesia, synesthesia); from the Greek (syn-) “union,” and (aesthesis) “sensation,” has been used to describe various phenomena. A person who experiences '''synaesthesia''' is called a ''synaesthete''. Normally the term '''synaesthesia''' is used to indicate a condition in which the stimulation of one sensory [[Sensory system#Modality|modality]] gives rise to an experience in another modality. In an [[Hearing (sense)|auditory]] synaesthete, for example, an auditory experience may give rise to an experience in the [[visual]] modality. |
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| + | Neurologist [http://Cytowic.net/ Richard Cytowic] (2003: 76-77; 2002:67-69) identifies the following 'diagnostic' criteria of synesthesia: |
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| − | Synaesthetes often experience correspondences between the [[shade]]s of color, [[tone]]s of sounds, and intensities of tastes that provoke alternate sensations. For instance, a synaesthete may see a more intense [[red]] as the pitch of a sound gets higher, or a smoother surface might make one taste a [[Basic taste#Sweetness|sweeter]] taste. These experiences are not [[metaphor]]ical or merely associations; rather, they are involuntary and are consistent throughout life, although some young synaesthetes seem to lose their ability by or during adulthood. [[Depressant]]s tend to increase the depth of the perception. |
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| + | # Synesthesia is involuntary and automatic |
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| + | # Synesthetic images are spatially extended, meaning they often having a definite 'location' |
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| + | # Synesthetic percepts are consistent and generic (i.e. simple rather than imagistic). |
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| + | # Synesthesia is highly memorable. |
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| + | # Synesthesia is laden with affect |
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| + | Dann (1998: 6-7) adds two more: |
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| − | Synaesthesia can even occur when one of the senses no longer functions properly, e.g., a person who can see colors when words are spoken can still see the colors if he becomes [[blindness|blind]] in later life. This phenomenon is known as "martian colors." The term originated from a case of a synaesthete who was born partially color blind, but saw certain 'alien' colors in his synaesthetic perceptions that he never saw (was incapable of seeing) in the 'real world.' |
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| + | * Synesthesia is nonlinguistic and somewhat ineffable. |
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| + | * Synesthesia occurs in people with normal, noninjured, nondiseased brains. |
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| + | == Synesthetic Experiences == |
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| − | The most common forms of synaesthesia involve color being assigned to letters, numbers, days of the week or (especially for musicians) musical keys. |
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| + | There are many varieties of synesthesia. While almost any sensory pairing is logically possible, certain combinations are much more common than others. In one of the most common forms of synesthesia, grapheme->color synaesthesia, individual letters of the alphabet, as well as numbers, are "shaded" or "tinged" with a color. While no two synesthetes will 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) (Day, 2005; Simner et al., 2005). |
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| − | [[Richard Cytowic]] wrote a [[pop psychology|pop-psych]] book about this condition entitled ''[[The Man Who Tasted Shapes]]''. |
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| ⚫ | Synaesthetes 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. Writer and synaesthete Patricia Lynne Duffy remembers one early experience: "'One day,' I said to my father, 'I realized that to make an 'R' all I had to do was first write a 'P' and then draw a line down from its loop. And I was so surprised that I could turn a yellow letter into an orange letter just by adding a line.'"<sup>[http://www.bluecatsandchartreusekittens.com/Blue_Cats_and_Chartreuse_Kittens_Ex.html]</sup> |
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| ⚫ | Another 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." (From a [http://slashdot.org/comments.pl?sid=140022&cid=11726211 slashdot discussion]) |
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| − | Some [[research]]ers and [[theory|theorists]] have suggested that synaesthesia may have played a part in early humans' development of writing and written [[literacy|literacies]]. |
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| + | Other synesthetes report that days of the week, months of the year, and numbers have specific spatial locations, or that numbers will have specific genders and personalities. |
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| − | ==Clinical description== |
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| − | A genuine type of synaesthesia shows the following qualities: |
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| − | * it is consistent: one stimulus always evokes a specific perception |
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| − | * the perception occurs involuntarily |
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| − | * the perceptions are individual: every Synaesthete has their "own" colors and shapes |
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| − | * the perceptions do not need to be reversible: a 7 might evoke the color blue, but the color blue doesn't need to evoke a 7 to be synaesthetic. |
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| − | * the perceptions are permanent: they begin in infancy and don't change throughout life. |
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| ⚫ | James Wannerton, a lexical-gustatory synaesthete reports: "Whenever I hear, read, or articulate (inner speech) words or word sounds, I experience an immediate and involuntary taste sensation on my tongue. These very specific taste associations never change and have remained the same for as long as I can remember". "<sup>[http://www.wannerton.net/]</sup> |
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| − | Researchers believe the phenomenon begins in infancy. Babies are said to perceive the world like a synaesthete, with mixed senses, because their brains are not completely developed. As the brain develops, the senses are separated from each other. For some people the separation does not take place and therefore they stay synaesthetes their whole life. |
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| − | Synaesthesia occurs eight times more often in women than in men. Often relatives of synaesthetes are synaesthetes as well. It is therefore likely that the phenomenon is either passed on on the [[X chromosome]] or is a sex influenced or a sex limited trait. |
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| + | == Notation == |
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| − | While synaesthesia occurs naturally in many individuals it is also a common effect of some [[Psychedelics, dissociatives and deliriants|hallucinogenic drug]]s such as [[LSD]] or [[mescaline]]. Synaesthesia as a drug effect played a role in the popular [[song]] "[[Lake Shore Drive]]" by [[Aliotta-Haynes-Jeremiah]]: |
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| + | Given the wide variety 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, and y is the "concurrent" or additional, extra experience. So, for example, seeing letters and numbers (collectively called graphemes) 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 by tone -> (color, movement) synesthesia. |
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| − | :Sometimes you can smell the green |
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| − | :When your mind is feeling fine |
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| − | : ( —Aliotta, Haynes and Jeremiah) |
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| + | == Demonstrating the Reality of Synesthesia == |
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| − | ==Types of perception== |
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| + | Proof that someone is a synesthete is fairly easy to come by, and hard to "fake". The simplest test involves test-retest reliability over long periods of time, and synesthetes consistently score higher on such tests than non-synesthetes (either with color names, color chips or even a color picker providing 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 are going to be retested (e.g., Baron-Cohen et al., 1996). |
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| + | More specialized tests include using modified versions of the [[Stroop|Stroop effect]]. In the standard Stroop paradigm, it is harder to name the ink color of the word "red" when it is printed in blue than if the word "blue" was presented in blue. This demonstrates that reading is "automatic". Similarly, if we present a grapheme-color synesthete with a four that they see as red, but present it in blue ink, they are slower to identify the ink color. Note that this is not because they cannot see the blue ink, but rather that the same sort of "response conflict" that is responsible for the standard Stroop effect is also occuring between the color of the ink and the automatically induced color of the grapheme. Similar variants of the Stroop can be devised where, for example, someone is asked to name a red color patch while listening to a tone that produces a blue sensation (Ward et al., 2006), or to identify a bitter taste while hearing a musical interval that induces a sweet taste (Beeli et al., 2005). |
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| + | [[Image:synaesthesiatest.jpg|thumb|right|300px|An example of a test used to demonstrate the reality of synesthetic experiences (from Ramachandran and Hubbard, 2001).]] |
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| + | 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]], Ramachandran and Hubbard (2001) 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 different shapes; square, diamond, triangle or diamond. For a synesthete who sees 2s as red and 5s as green, their synesthetic colors would be expected to help them to find the "embedded figure". This is indeed what was found. 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. |
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| + | ==Case studies== |
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| − | Another account: "I have synesthesia, and as a child I thought it was normal until I realized other people didn't see numbers and letters as colors. I believe synesthesia can link any kind of sensory input to abstract forms like letters and numbers, but in my case (and in most), it's simple colors. This makes it easy for me to remember trivial information like [[phone number]]s, account numbers, historical [[date]]s, and [[pi]] (3.141592653589 is how far I remember without looking it up). Every string of numbers and letters forms a composite color based on those of its individual characters. I've studied Japanese for a few years and now find that [[Kana|Japanese syllable characters]] also have colors for me now. I imagine that with extreme synesthesia, a person might understand abstract notions like numbers and [[mathematics|math]] in a completely different way. I remember once showing my sister two [[Smarties (Nestlé)|Smarties]] and telling her they were '[[3 (number)|3]]' and '[[6 (number)|6]]' instead of [[yellow]] and [[green]]. It took me a moment to realize why she didn't understand." (From a [http://slashdot.org/comments.pl?sid=140022&threshold=-1&commentsort=0&tid=99&mode=nested&pid=11725481 slashdot discussion]) |
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| + | Over the last 100 years there have been a number of case studies reported in the scientific literature and there have been references in the biographies of notable artists indicating that they experienced the condition. |
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| + | {{Main| Case studies in synesthesia}} |
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| − | Researchers at the [[University of California, San Diego]] documented the case of a man named Daniel Tammet who is strongly synaesthetic with regard to numbers, assigning them shapes, sizes, colors, textures, and sometimes movements or sounds. He was able to identify large [[prime number]]s rapidly because he perceived them to have a different texture from [[composite number]]s.[http://psy.ucsd.edu/~sazoulai/Azoulai_CNS20051-%20Small.ppt] |
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| + | == Prevelance == |
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| + | Estimates of the prevelance of synesthesia have varied widely (from 1 in 20 to 1 in 20000). However, these previous studies all suffered from the methodological shortcoming of relying on [[Self-selection|self-selected]] samples. That is, the only people included in those earlier studies were those who reported their experiences to the experimenter. Simner et al., (in press) conducted the first random population study, arriving at a prevalence of 1 on 23. Recent data (Day, 2005; Simner et al., in press) suggests that grapheme -> color, and days of the week -> color variants are most common. |
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| + | ==Genetic basis== |
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| − | There are a lot of different types of Synaesthesia, of which the connection between grapheme and color is the mostly distributed type, followed by the connection between time units and color and musical sounds and color.[http://home.comcast.net/~sean.day/html/types.htm]. |
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| + | Almost every study that has investigated the topic has suggested that synesthesia clusters within families, consistent with a genetic origin for the condition. |
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| + | {{Main| The genetic basis of synasthesia}} |
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| − | ==Studies of synaesthesia== |
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| − | It is estimated that 10% of people are synaesthetes, but only those perceiving their synaesthesia can recognize the inner colors. <sup>[http://www.synaesthesia.ch]</sup> Synaesthetes have been studied by neurologist [[Vilayanur S. Ramachandran|V. S. Ramachandran]] at the [[University of California, San Diego]], who remarked that "processes similar to synaesthesia might also underlie our general capacity for metaphor and be critical to creativity."<sup>[http://www.sciam.com/print_version.cfm?articleID=0003014B-9D06-1E8F-8EA5809EC5880000][http://news.bbc.co.uk/1/hi/health/4375977.stm]</sup> Ramachandran has said it is "not an accident" that the phenomenon is noted eight times more frequently in writers and artists than in the typical population, and is more common in creative people.<sup>[http://news.bbc.co.uk/1/hi/health/4375977.stm]</sup> Synaesthesia often runs in families. About one-third of synaesthetes report that another family member experiences similar phenomena.<sup>[http://www.synaesthesia.uwaterloo.ca/genetics.htm]</sup> |
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| + | == Possible Neural Basis == |
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| − | Another leading psychologist, [[Simon Baron-Cohen|Prof. Simon Baron-Cohen]], currently a fellow at [[Trinity College, Cambridge]], is also undergoing research into the topic. |
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| + | {{main| The neurological basis of synesthesia}} |
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| − | == |
+ | == Associated Cognitive Traits == |
| + | In general very little is definitively 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 synsthetes are unusually sensitive to external stimuli (see, e.g., Cytowic, 2002). Other possible associated cognitive traits include left-right confusion, difficutlies with math, and difficulties with writing (Cytowic, 2002). However, synesthetes may be more likely to participate in creative activities (Rich et al., 2005), and some studies have suggested a correlation between synesthesia and creativity (Domino, 1989; Dailey et al., 1991). Other research has sugggested that synesthesia may contribute to superior memory abilities (Luria, 1968; Smilek et al., 2002). However, it is unclear whether this is a general feature of synesthesia or whether it is true of only a small minority. This is a major topic of current and future research. |
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| − | Synaesthesia is an often-used [[figure of speech|poetic device]]. In a familiar example, [[Andrew Marvell]] characterized the fruitful and serene atmosphere of the [[garden]] as |
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| − | :Annihilating all that's made |
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| − | :To a green thought in a green shade |
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| − | : ( —"The Garden") |
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| + | == Links with Other Areas of Study == |
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| − | Artist Shem Booth-Spain put forward the idea that synesthesia "provides a understanding of how perception is rooted to a sensory dominance in modern culture" and that synaesthesia is essentually a higher faculty that has been programmed out of human perception. |
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| ⚫ | [[Image:BoobaKiki.png|thumb|right|250px|Booba and Kiki shapes|This picture is used as a test to demonstrate that people may not attach sounds to shapes arbitrarily: A remote tribe calls one of these shapes '''Booba''' and the other '''Kiki.''' Decide which is which and then click the image to check your answer.]] |
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| + | Researchers study synaesthesia not only because it is inherently interesting, but also because they hope that studying synaesthesia will offer new insights into other questions, such as how the brain combines information from different sensory modalities, referred to as [[Crossmodal|cross-modal perception]] and [[Multisensory_integration|multisensory integration]]. One example of this is the "kiki/bouba effect" (see image at right). This example was first explored by the [[Gestalt_Psychology|Gestalt psychologist]] [[Wolfgang_Köhler|Wolfgang Kohler]]. With individuals on the island of Tenerife, Kohler 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 (too young to read) show this effect. Ramachandran and Hubbard (2001) have argued that this effect might be the neurological basis for [[sound_symbolism|sound symbolism]], in which sounds are non-arbitrarily mapped to objects and events in the world. |
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| + | Similarly, synaesthesia researchers hope that, because of their unusual conscious experiences, the study of synaesthesia will provide a window into better understanding [[Consciousness|consciousness]] and in particular on the [[Neural_correlate|neural correlates]] of consciousness, or what the brain mechanisms that allow us to be conscious might be. In particular, some researchers have argued that synaesthesia is relevant to the [[philosophy|philosophical]] problem of [[qualia]] (see, e.g., Gray et al., 2002; Gray et al., 1997; Ramachandran & Hubbard, 2001), since synaesthetes experience additional qualia evoked through non-typical routes. |
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| − | As digital entertainment becomes more developed, the possibility of synaesthesia through technology has begun to be considered. Several [[computer and video games|video games]] already use the term in their [[advertising]], most notably the 2001 [[Dreamcast]]/[[PlayStation 2]] game ''[[REZ]]'' (which does have some elements of synaesthesia in its [[gameplay]], notably the interaction of [[game controller|controller]] vibration, music, player interaction and [[graphics]]). |
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| + | ==See also== |
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| − | ==People with synaesthetic experiences== |
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| − | Synaesthesia has influenced [[artist]]s in many fields as well as other gifted individuals. |
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| + | *[[Sensory substitution]] |
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| + | ==References== |
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| − | *[[Aphex Twin]], electronic music artist. |
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| + | * Baron-Cohen, Simon, and John E. Harrison, eds., 1997. Synaesthesia: Classic and Contemporary Readings. Oxford, UK: Blackwell. |
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| − | *[[Syd Barrett]], lead singer/songwriter of [[Pink Floyd]]. |
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| + | * Baron-Cohen, Simon, John Harrison, Laura H. Goldstein, and Maria Wyke, 1993. "Coloured Speech Perception: Is Synaesthesia What Happens When Modularity Breaks Down?" Perception; volume 22: 419-426. |
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| − | *[[Amy Beach]], pianist, associated colors with keys, as well as possessing [[absolute pitch]]. |
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| + | * Beeli, Gian, Michaela Esslen, and Lutz Jäncke, 2005. “When coloured sounds taste sweet.” Nature; vol. 434; 3 March: 38. |
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| − | *[[Ludwig van Beethoven]], composer, considered B minor to be "the black key,". |
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| + | * [http://Cytowic.net/ Cytowic, Richard E.], 2003/1993. [http://cytowic.net/_Books/_books.html The Man Who Tasted Shapes]. New York: Tarcher/Putnam. |
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| − | *[[Charles-Pierre Baudelaire]], poet. |
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| + | * [http://Cytowic.net/ Cytowic, Richard E.] 2002. [http://cytowic.net/_Books/_books.html Synesthesia: A Union of the Senses, 2nd ed]. Cambridge: MIT Press. |
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| − | *[[Richard Feynman]], physicist, saw algebraic symbols of [[Bessel function]]s in [[color]]. |
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| + | * Dann, Kevin T., 1998. Bright Colors Falsely Seen: Synaesthesia and the Search for Transcendent Knowledge. New Haven; London: Yale University Press. |
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| − | *[[Stephen Hargreaves]] |
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| + | * Day, Sean A., 2005. “Some Demographic and Socio-cultural Aspects of Synesthesia.” In Robertson & Sagiv, eds.; Synesthesia: Perspectives from Cognitive Neuroscience; Oxford: University Press, 11-33. |
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| − | *[[Jimi Hendrix]], guitarist, described chords and harmony in terms of color. For example, the chord E7#9 (often referred to by guitar players as the '[[Hendrix chord]]') gave him a strong sense of the color purple. The chord is played under the words 'purple haze' in each verse of the song of that name. |
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| + | * Duffy, Patricia Lynne, 2001. Blue Cats and Charteuse Kittens. New York: Henry Holt & Company. |
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| − | *[[Robyn Hitchcock]], musician, associates "colours" with chords. |
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| + | * Gray, J. A., Chopping, S., Nunn, J., Parslow, D., Gregory, L., Williams, S., et al. (2002). "Implications of synaesthesia for functionalism: Theory and experiments." Journal of Consciousness Studies, 9(12), 5-31. |
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| − | *[[Adam Jones]], guitarist, associates music and shapes, and often gains musical inspiration while sculpting. |
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| + | * Gray, J. A., Williams, S. C. R., Nunn, J., & Baron-Cohen, S. (1997). "Possible implications of synaesthesia for the hard question of consciousness." In S. Baron-Cohen & J. E. Harrison (Eds.), Synaesthesia: Classic and contemporary readings. (pp. 173-181). Malden, MA: Blackwell.[http://psy.ucsd.edu/~edhubbard/papers/JCS.pdf pdf] |
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| − | *[[Wassily Kandinsky]], artist, was able to hear as well as see colors. |
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| + | * Ramachandran, V.S. & Hubbard, E.M. (2001)."Synaesthesia: A window into perception, thought and language."] Journal of Consciousness Studies, 8(12), 3-34. |
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| − | *[[Manu Katché]], drummer, sees images with music. |
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| + | * Smilek, Daniel, B.A. Moffatt, J. Pasternak, B.N. White, M.J. Dixon, and P.M. Merikle, 2002. "Synaesthesia: a case study of discordant monozygotic twins." Neurocase; vol. 8: 338-342. |
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| − | *[[György Ligeti]] |
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| + | * Steen, Carol J., 2001. "Visions Shared: A Firsthand Look into Synesthesia and Art." Boston: Leonardo, The MIT Press: Vol 34, No. 3. |
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| − | *[[Franz Liszt]], composer, described [[timbre]]s or sonorities to musicians in chromatic terms.<sup>[http://home.comcast.net/~sean.day/syn-composers.htm]</sup> |
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| + | *Wheeler, RH. and Cutsforth, T.D. (1925) Synaesthesia in the development of the concept, Journal of Experimental Psychology 8: 149-52. |
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| − | *[[Olivier Messiaen]] described in his writings the colorations evoked by particular chords. |
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| − | *[[Vladimir Nabokov]] |
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| − | *[[Jennifer Paull]], oboist, perceived sounds in a visual spectrum and found the sensation of the oboe particularly compelling. |
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| − | *[[Arthur Rimbaud]] poet (specifically his [[poem]] ''Voyelles''). |
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| − | *[[Nikolai Rimsky-Korsakov]], composer. |
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| − | *[[Franz Schubert]] viewed E minor as like "a maiden robed in white and with a rose-red bow on her breast."<sup>[http://www.synsation.org/episodesFull1.html]</sup> |
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| − | *[[Jean Sibelius]], claimed in early childhood that G major was 'green' and could convert images he saw in nature directly into music. |
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| − | *[[Michael Torke]], composer, perceives colors for various time units. |
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| − | *[[Frank Lloyd Wright]], architect, claimed to hear music sometimes while designing buildings. |
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| − | *[[Judifer Yellich]], artist, painted an entire series of abstract paintings known as 'The Wave & Particle Series', devoted completely to painting or "composing" music with colors and shapes. |
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| − | "Only We Matter" has been noted to show a reference to color interpretation in people's mind which leads one to believe that synaesthesia is present. |
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| + | === Synesthesia associations === |
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| − | *[[John Mayer]], popular singer/songwriter. |
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| + | * [http://synesthesia.info/ American Synesthesia Association] |
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| − | ==Synesthesia |
+ | === Synesthesia community sites === |
| − | *[http:// |
+ | *[http://www.syn6th.com/ Synesthesia in Chinese] |
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| − | == |
+ | === Scientific resources === |
| + | *[http://www.synesthete.org/ The Synesthesia Battery:] take the tests to discover if you are synesthetic. Developed by David Eagleman, PhD. |
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| + | *[http://Cytowic.net/ Richard E. Cytowic, MD] Downloads and information. |
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| − | * [[Noise health effects]] |
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| + | *[http://psy.ucsd.edu/~edhubbard Edward M. Hubbard, PhD] Synesthesia research including pdf versions of scientific articles. |
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| − | * [[Over-illumination]] |
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| − | * [[Schmidt Sting Pain Index]] (A good example.) |
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| − | * [[Tele-synaesthesia]] |
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| + | === Synesthesia articles on the web === |
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| − | *[http://www.freeinfosociety.com/site.php?postnum=693 Interview with a Synesthete] |
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| − | *[http://colorofmysound.com ColorOfMySound.com] Upload your own audio track and let the world weigh in on what color it looks like. A community driven version of the Color Of Sound experiment below. |
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*[http://www.cortex-online.org/cortex.asp?action=toArticles&folderID=176 Cortex: Special Issue on Cognitive Neuroscience Perspectives on Synesthesia] The neuroscience journal Cortex presents a special issue focusing on modern scientific research of synesthesia. |
*[http://www.cortex-online.org/cortex.asp?action=toArticles&folderID=176 Cortex: Special Issue on Cognitive Neuroscience Perspectives on Synesthesia] The neuroscience journal Cortex presents a special issue focusing on modern scientific research of synesthesia. |
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| + | === Artificial synesthesia === |
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| − | *[http://www.migraine-aura.org/EN/Synaesthesia.html Synaesthesia and Migraine]Synaesthesia may occur as a visual migraine aura. |
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| − | *[http://livescience.com/humanbiology/050222_synesthesia.html People who feel color gets scientific acceptance] |
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| − | *[http://www.thereminvox.com/story/28/ A Brief History of Synaesthesia and Music] |
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| − | *[http://www.wendymass.com/ A Mango-Shaped Space, a novel about a 13-year-old with synesthesia by Wendy Mass] |
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| − | *[http://www.kuro5hin.org/story/2003/2/21/144256/437 Synaesthesia - union of the senses] (from [[Kuro5hin]]) |
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| − | *[http://news.bbc.co.uk/1/hi/health/4375977.stm Why some see colours in numbers] at [[BBC News]], [[24 March]], [[2005]] |
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*[http://www.seeingwithsound.com/asynesth.htm Artificial synesthesia (for the blind)] |
*[http://www.seeingwithsound.com/asynesth.htm Artificial synesthesia (for the blind)] |
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| − | *[http://develintel.blogspot.com/2005/12/tuned-and-pruned-synaesthesia_22.html Infantile synaesthesia] |
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*[http://www.synestesia.fi/ Synesthesia Music] Music generated from any pictures in 5 seconds |
*[http://www.synestesia.fi/ Synesthesia Music] Music generated from any pictures in 5 seconds |
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| − | *[http://www.creatingmusic.com/mmm/mmm.html Draw your music |
+ | *[http://www.creatingmusic.com/mmm/mmm.html Draw your music] Software plays what you draw |
| − | *[http://www.musanim.com/mam/mam.html Visualising Music |
+ | *[http://www.musanim.com/mam/mam.html Visualising Music] Software displays your music to animation |
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| − | *[http://synesthete.org/ The synesthesia battery] |
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| − | *[http://www.abc.net.au/science/news/stories/s1119739.htm Mirror Writing could be linked to Synaesthesia] |
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| − | *[http://medialab.freaknet.org.shem/ shem booth-spain, synesthesia, cybernetic culture] |
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| − | [[da:Synæstesi]] |
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| − | [[it:Sinestesia (psicologia)]] |
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| − | [[he:סינסתזיה]] |
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| − | [[ja:共感覚]] |
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Revision as of 07:38, 27 October 2012
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Cognitive Psychology: Attention · Decision making · Learning · Judgement · Memory · Motivation · Perception · Reasoning · Thinking - Cognitive processes Cognition - Outline Index
Synesthesia (also spelled synæsthesia or synaesthesia) - from the Greek syn- meaning union and aesthesis meaning sensation, is a neurological condition in which two or more bodily senses are coupled. For example, in a form of synaesthesia known as grapheme-color synaesthesia, letters or numbers may be perceived as inherently colored. In other forms of synesthesia, musical and other sounds may be perceived as colored or having particular shapes. While cross-sensory metaphors are sometimes described as "synesthetic", true neurological synesthesia is involuntary and occurrs in about four percent of the population (1 in 23 persons) across its range of variants (see Simner et al., in press). It runs strongly in families, possibly inherited as an X-linked dominant trait.
Markus Zedler describes in a brief article synesthesia as "a perceptual condition in which the stimulation in one sensory modality elicits a concurrent sensation in another, a perception which is perceived as real."
Neurologist Richard Cytowic (2003: 76-77; 2002:67-69) identifies the following 'diagnostic' criteria of synesthesia:
- Synesthesia is involuntary and automatic
- Synesthetic images are spatially extended, meaning they often having a definite 'location'
- Synesthetic percepts are consistent and generic (i.e. simple rather than imagistic).
- Synesthesia is highly memorable.
- Synesthesia is laden with affect
Dann (1998: 6-7) adds two more:
- Synesthesia is nonlinguistic and somewhat ineffable.
- Synesthesia occurs in people with normal, noninjured, nondiseased brains.
Synesthetic Experiences
How someone with synaesthesia might perceive (n.b., not 'see') certain letters and numbers.
There are many varieties of synesthesia. While almost any sensory pairing is logically possible, certain combinations are much more common than others. In one of the most common forms of synesthesia, grapheme->color synaesthesia, individual letters of the alphabet, as well as numbers, are "shaded" or "tinged" with a color. While no two synesthetes will 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) (Day, 2005; Simner et al., 2005).
Synaesthetes 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. Writer and synaesthete Patricia Lynne Duffy remembers one early experience: "'One day,' I said to my father, 'I realized that to make an 'R' all I had to do was first write a 'P' and then draw a line down from its loop. And I was so surprised that I could turn a yellow letter into an orange letter just by adding a line.'"[1]
Another 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." (From a slashdot discussion)
Other synesthetes report that days of the week, months of the year, and numbers have specific spatial locations, or that numbers will have specific genders and personalities.
James Wannerton, a lexical-gustatory synaesthete reports: "Whenever I hear, read, or articulate (inner speech) words or word sounds, I experience an immediate and involuntary taste sensation on my tongue. These very specific taste associations never change and have remained the same for as long as I can remember". "[2]
Notation
Given the wide variety 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, and y is the "concurrent" or additional, extra experience. So, for example, seeing letters and numbers (collectively called graphemes) 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 by tone -> (color, movement) synesthesia.
Demonstrating the Reality of Synesthesia
Proof that someone is a synesthete is fairly easy to come by, and hard to "fake". The simplest test involves test-retest reliability over long periods of time, and synesthetes consistently score higher on such tests than non-synesthetes (either with color names, color chips or even a color picker providing 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 are going to be retested (e.g., Baron-Cohen et al., 1996).
More specialized tests include using modified versions of the Stroop effect. In the standard Stroop paradigm, it is harder to name the ink color of the word "red" when it is printed in blue than if the word "blue" was presented in blue. This demonstrates that reading is "automatic". Similarly, if we present a grapheme-color synesthete with a four that they see as red, but present it in blue ink, they are slower to identify the ink color. Note that this is not because they cannot see the blue ink, but rather that the same sort of "response conflict" that is responsible for the standard Stroop effect is also occuring between the color of the ink and the automatically induced color of the grapheme. Similar variants of the Stroop can be devised where, for example, someone is asked to name a red color patch while listening to a tone that produces a blue sensation (Ward et al., 2006), or to identify a bitter taste while hearing a musical interval that induces a sweet taste (Beeli et al., 2005).
An example of a test used to demonstrate the reality of synesthetic experiences (from Ramachandran and Hubbard, 2001).
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, Ramachandran and Hubbard (2001) 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 different shapes; square, diamond, triangle or diamond. For a synesthete who sees 2s as red and 5s as green, their synesthetic colors would be expected to help them to find the "embedded figure". This is indeed what was found. 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.
Case studies
Over the last 100 years there have been a number of case studies reported in the scientific literature and there have been references in the biographies of notable artists indicating that they experienced the condition.
- Main article: Case studies in synesthesia
Prevelance
Estimates of the prevelance of synesthesia have varied widely (from 1 in 20 to 1 in 20000). However, these previous studies all suffered from the methodological shortcoming of relying on self-selected samples. That is, the only people included in those earlier studies were those who reported their experiences to the experimenter. Simner et al., (in press) conducted the first random population study, arriving at a prevalence of 1 on 23. Recent data (Day, 2005; Simner et al., in press) suggests that grapheme -> color, and days of the week -> color variants are most common.
Genetic basis
Almost every study that has investigated the topic has suggested that synesthesia clusters within families, consistent with a genetic origin for the condition.
- Main article: The genetic basis of synasthesia
Possible Neural Basis
- Main article: The neurological basis of synesthesia
Associated Cognitive Traits
In general very little is definitively 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 synsthetes are unusually sensitive to external stimuli (see, e.g., Cytowic, 2002). Other possible associated cognitive traits include left-right confusion, difficutlies with math, and difficulties with writing (Cytowic, 2002). However, synesthetes may be more likely to participate in creative activities (Rich et al., 2005), and some studies have suggested a correlation between synesthesia and creativity (Domino, 1989; Dailey et al., 1991). Other research has sugggested that synesthesia may contribute to superior memory abilities (Luria, 1968; Smilek et al., 2002). However, it is unclear whether this is a general feature of synesthesia or whether it is true of only a small minority. This is a major topic of current and future research.
Links with Other Areas of Study
This picture is used as a test to demonstrate that people may not attach sounds to shapes arbitrarily: A remote tribe calls one of these shapes Booba and the other Kiki. Decide which is which and then click the image to check your answer.
Researchers study synaesthesia not only because it is inherently interesting, but also because they hope that studying synaesthesia will offer new insights into other questions, such as how the brain combines information from different sensory modalities, referred to as cross-modal perception and multisensory integration. One example of this is the "kiki/bouba effect" (see image at right). This example was first explored by the Gestalt psychologist Wolfgang Kohler. With individuals on the island of Tenerife, Kohler 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 (too young to read) show this effect. Ramachandran and Hubbard (2001) have argued that this effect might be the neurological basis for sound symbolism, in which sounds are non-arbitrarily mapped to objects and events in the world.
Similarly, synaesthesia researchers hope that, because of their unusual conscious experiences, the study of synaesthesia will provide a window into better understanding consciousness and in particular on the neural correlates of consciousness, or what the brain mechanisms that allow us to be conscious might be. In particular, some researchers have argued that synaesthesia is relevant to the philosophical problem of qualia (see, e.g., Gray et al., 2002; Gray et al., 1997; Ramachandran & Hubbard, 2001), since synaesthetes experience additional qualia evoked through non-typical routes.
See also
- Cognitive neuroscience
- Perception
- Kinesthesia
- Parosmia
- Multiple Intelligence (Learning using multiple senses)
- Sensory substitution
- Visual thinking
References
- Baron-Cohen, Simon, and John E. Harrison, eds., 1997. Synaesthesia: Classic and Contemporary Readings. Oxford, UK: Blackwell.
- Baron-Cohen, Simon, John Harrison, Laura H. Goldstein, and Maria Wyke, 1993. "Coloured Speech Perception: Is Synaesthesia What Happens When Modularity Breaks Down?" Perception; volume 22: 419-426.
- Beeli, Gian, Michaela Esslen, and Lutz Jäncke, 2005. “When coloured sounds taste sweet.” Nature; vol. 434; 3 March: 38.
- Cytowic, Richard E., 2003/1993. The Man Who Tasted Shapes. New York: Tarcher/Putnam.
- Cytowic, Richard E. 2002. Synesthesia: A Union of the Senses, 2nd ed. Cambridge: MIT Press.
- Dann, Kevin T., 1998. Bright Colors Falsely Seen: Synaesthesia and the Search for Transcendent Knowledge. New Haven; London: Yale University Press.
- Day, Sean A., 2005. “Some Demographic and Socio-cultural Aspects of Synesthesia.” In Robertson & Sagiv, eds.; Synesthesia: Perspectives from Cognitive Neuroscience; Oxford: University Press, 11-33.
- Duffy, Patricia Lynne, 2001. Blue Cats and Charteuse Kittens. New York: Henry Holt & Company.
- Gray, J. A., Chopping, S., Nunn, J., Parslow, D., Gregory, L., Williams, S., et al. (2002). "Implications of synaesthesia for functionalism: Theory and experiments." Journal of Consciousness Studies, 9(12), 5-31.
- Gray, J. A., Williams, S. C. R., Nunn, J., & Baron-Cohen, S. (1997). "Possible implications of synaesthesia for the hard question of consciousness." In S. Baron-Cohen & J. E. Harrison (Eds.), Synaesthesia: Classic and contemporary readings. (pp. 173-181). Malden, MA: Blackwell.pdf
- Ramachandran, V.S. & Hubbard, E.M. (2001)."Synaesthesia: A window into perception, thought and language."] Journal of Consciousness Studies, 8(12), 3-34.
- Smilek, Daniel, B.A. Moffatt, J. Pasternak, B.N. White, M.J. Dixon, and P.M. Merikle, 2002. "Synaesthesia: a case study of discordant monozygotic twins." Neurocase; vol. 8: 338-342.
- Steen, Carol J., 2001. "Visions Shared: A Firsthand Look into Synesthesia and Art." Boston: Leonardo, The MIT Press: Vol 34, No. 3.
- Wheeler, RH. and Cutsforth, T.D. (1925) Synaesthesia in the development of the concept, Journal of Experimental Psychology 8: 149-52.
External links
Synesthesia associations
- American Synesthesia Association
- Australian Synaesthesia Association
- Belgian Synesthesia Association
- UK Synaesthesia Association
Synesthesia community sites
- Synesthesia in Chinese
- A forum with discussions concerning many different types of synesthesia
- A community of synesthetes on livejournal.com, for discussion and sharing of personal experiences and theories
- Blue Cats and Chartreuse Kittens by Patricia Lynne Duffy
Scientific resources
- The Synesthesia Battery: take the tests to discover if you are synesthetic. Developed by David Eagleman, PhD.
- Richard E. Cytowic, MD Downloads and information.
- Edward M. Hubbard, PhD Synesthesia research including pdf versions of scientific articles.
- Crétien van Campen 'Artistic and psychological experiments with synesthesia' gives the historical background.
- Synaesthesia and Education: a research project at the University of Cambridge investigating the effects of grapheme-colour synaesthesia on numerical processing in children.
- Museums of the Mind, a synesthesia portal by Dr. Hugo Heyrman, more specific on the interaction between art and synesthesia.
Synesthesia articles on the web
- Scientific American article Hearing Colors, Tasting Shapes (PDF version) by Vilayanur S. Ramachandran and Edward M. Hubbard, May 2003.
- Cortex: Special Issue on Cognitive Neuroscience Perspectives on Synesthesia The neuroscience journal Cortex presents a special issue focusing on modern scientific research of synesthesia.
Artificial synesthesia
- Artificial synesthesia (for the blind)
- The Color of Sound Flash experiment where you can assign colors to sounds and see how other people voted.
- Synesthesia Music Music generated from any pictures in 5 seconds
- Draw your music Software plays what you draw
- Visualising Music Software displays your music to animation
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