From Wikipedia, the free encyclopedia
| Synesthesia |
|---|
| Other names | Synaesthesia |
|---|
 |
| How
someone with synesthesia might perceive certain letters and numbers.
Synesthetes see characters just as others do (in whichever color
actually displayed) but may simultaneously perceive colors as associated
with or evoked by each one. |
| Specialty | Psychiatry, neurology |
|---|
Synesthesia or synaesthesia is a perceptual phenomenon in which stimulation of one sensory or cognitive pathway leads to involuntary experiences in a second sensory or cognitive pathway. People who report a lifelong history of such experiences are known as synesthetes. Awareness of synesthetic perceptions varies from person to person. In one common form of synesthesia, known as grapheme–color synesthesia or color–graphemic synesthesia, letters or numbers are perceived as inherently colored. In spatial-sequence, or number form
synesthesia, numbers, months of the year, or days of the week elicit
precise locations in space (for example, 1980 may be "farther away" than
1990), or may appear as a three-dimensional map (clockwise or
counterclockwise). Synesthetic associations can occur in any combination and any number of senses or cognitive pathways.
Little is known about how synesthesia develops. It has been
suggested that synesthesia develops during childhood when children are
intensively engaged with abstract concepts for the first time. This hypothesis – referred to as semantic vacuum hypothesis
– explains why the most common forms of synesthesia are grapheme-color,
spatial sequence and number form. These are usually the first abstract
concepts that educational systems require children to learn.
Difficulties have been recognized in adequately defining synesthesia.
Many different phenomena have been included in the term synesthesia
("union of the senses"), and in many cases the terminology seems to be
inaccurate. A more accurate but less common term may be ideasthesia.
The earliest recorded case of synesthesia is attributed to the Oxford University academic and philosopher John Locke, who, in 1690, made a report about a blind man who said he experienced the color scarlet when he heard the sound of a trumpet. However, there is disagreement as to whether Locke described an actual instance of synesthesia or was using a metaphor. The first medical account came from German physician Georg Tobias Ludwig Sachs in 1812. The term is from the Ancient Greek σύν syn, 'together', and αἴσθησις aisthēsis, 'sensation'.
Types
There are two overall forms of synesthesia:
- projective synesthesia: people who see actual colors, forms, or
shapes when stimulated (the widely understood version of synesthesia).
- associative synesthesia: people who feel a very strong and
involuntary connection between the stimulus and the sense that it
triggers.
For example, in chromesthesia (sound to color), a projector may hear a trumpet, and see an orange triangle in space, while an associator might hear a trumpet, and think very strongly that it sounds "orange".
Synesthesia can occur between nearly any two senses or perceptual modes, and at least one synesthete, Solomon Shereshevsky, experienced synesthesia that linked all five senses.
Types of synesthesia are indicated by using the 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 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 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, individual letters of the alphabet and numbers (collectively referred to as graphemes)
are "shaded" or "tinged" with a color. While different individuals
usually do not report the same colors for all letters and numbers,
studies with large numbers of synesthetes find some commonalities across
letters (e.g., A is likely to be red).
Chromesthesia
Another common form of synesthesia is the association of sounds with
colors. For some, everyday sounds such as doors opening, cars honking,
or people talking can trigger seeing colors. For others, colors are
triggered when musical notes or keys are being played. People with
synesthesia related to music may also have perfect pitch because their ability to see/hear colors aids them in identifying notes or keys.
The colors triggered by certain sounds, and any other synesthetic visual experiences, are referred to as photisms.
According to Richard Cytowic,
chromesthesia is "something like fireworks": voice, music, and assorted
environmental sounds such as clattering dishes or dog barks trigger
color and firework shapes that arise, move around, and then fade when
the sound ends. Sound often changes the perceived hue, brightness,
scintillation, and directional movement. Some individuals see music on a
"screen" in front of their faces. For Deni Simon, music produces waving
lines "like oscilloscope configurations – lines moving in color, often
metallic with height, width and, most importantly, depth. My favorite
music has lines that extend horizontally beyond the 'screen' area."
Individuals rarely agree on what color a given sound is. B flat might be orange for one person and blue for another. Composers Franz Liszt and Nikolai Rimsky-Korsakov famously disagreed on the colors of musical keys.
Spatial sequence synesthesia
Those
with spatial sequence synesthesia (SSS) tend to see numerical sequences
as points in space. For instance, the number 1 might be farther away
and the number 2 might be closer. People with SSS may have superior
memories; in one study, they were able to recall past events and
memories far better and in far greater detail than those without the
condition. They also see months or dates in the space around them. Some
people see time like a clock above and around them.
Number form
A
number form is a mental map of numbers that automatically and
involuntarily appear whenever someone who experiences number-forms
synesthesia thinks of numbers. These numbers might appear in different
locations and the mapping changes and varies between individuals. Number
forms were first documented and named in 1881 by Francis Galton in "The Visions of Sane Persons".
It is suggested that this might be caused by “cross activation” of the
neural pathway that connects the parietal lobes and angular gyrus. Both
of these areas are involved in numerical cognition and spatial cognition
respectively.
A
number form from one of Francis Galton's subjects (1881). Note how the first 4 digits roughly correspond to their positions on a clock face.
Auditory-tactile synesthesia
In auditory-tactile synesthesia,
certain sounds can induce sensations in parts of the body. For example,
someone with auditory-tactile synesthesia may experience that hearing a
specific word or sound feels like touch in one specific part of the
body or may experience that certain sounds can create a sensation in the
skin without being touched. Not to be confused with the milder general
reaction known as frisson, which affects approx 50% of the population. It is one of the least common forms of synesthesia.
Ordinal linguistic personification
Ordinal-linguistic personification (OLP, or personification for
short) is a form of synesthesia in which ordered sequences, such as ordinal numbers, week-day names, months and alphabetical letters are associated with personalities or genders (Simner & Hubbard 2006).
For example, the number 2 might be a young boy with a short temper, or
the letter G might be a busy mother with a kind face. Although this form
of synesthesia was documented as early as the 1890s (Flournoy 1893; Calkins 1893) researchers have, until recently, paid little attention to this form (see History of synesthesia research). This form of synesthesia was named as OLP in the contemporary literature by Julia Simner and colleagues although it is now also widely recognised by the term
"sequence-personality" synesthesia. Ordinal linguistic personification
normally co-occurs with other forms of synesthesia such as grapheme-color synesthesia.
Misophonia
Misophonia
is a neurological disorder in which negative experiences (anger,
fright, hatred, disgust) are triggered by specific sounds. Cytowic
suggests that misophonia is related to, or perhaps a variety of,
synesthesia.
Edelstein and her colleagues have compared misophonia to synesthesia in
terms of connectivity between different brain regions as well as
specific symptoms.
They formed the hypothesis that "a pathological distortion of
connections between the auditory cortex and limbic structures could
cause a form of sound-emotion synesthesia."
Studies suggest that individuals with misophonia have a normal hearing
sensitivity level but the limbic system and autonomic nervous system are
constantly in a “heightened state of arousal” where abnormal reactions
to sounds will be more prevalent.
Newer studies suggest that depending on its severity, misophonia
could be associated with lower cognitive control when individuals are
exposed to certain associations and triggers.
It is unclear what causes misophonia. Some scientists believe it
could be genetic, others believe it to be present with other additional
conditions however there is not enough evidence to conclude what causes
it. There are no current treatments for the condition but could be managed with different types of coping strategies.
These strategies vary from person to person, some have reported the
avoidance of certain situations that could trigger the reaction:
mimicking the sounds, cancelling out the sounds by using different
methods like earplugs, music, internal dialog and many other tactics.
Most misophonics use these to “overwrite” these sounds produced by
others.
Mirror-touch synesthesia
This is a form of synesthesia where individuals feel the same
sensation that another person feels (such as touch). For instance, when
such a synesthete observes someone being tapped on their shoulder, the
synesthete involuntarily feels a tap on their own shoulder as well.
People with this type of synesthesia have been shown to have higher empathy levels compared to the general population. This may be related to the so-called mirror neurons present in the motor areas of the brain, which have also been linked to empathy.
Lexical-gustatory synesthesia
This is another form of synesthesia where certain tastes are
experienced when hearing words. For example, the word basketball might
taste like waffles. The documentary 'Derek Tastes Of Earwax' gets its
name from this phenomenon, in references to pub owner James Wannerton
who experiences this particular sensation whenever he hears the name
spoken. It is estimated that 0.2% of the synesthesia population has this form of synesthesia, making it the rarest form.
Kinesthetic synesthesia
Kinesthetic synesthesia is one of the rarest documented forms of synesthesia in the world.
This form of synesthesia is a combination of various different types of
synesthesia. Features appear similar to auditory-tactile synesthesia
but sensations are not isolated to individual numbers or letters but
complex systems of relationships. The result is the ability to memorize
and model complex relationships between numerous variables by feeling
physical sensations around the kinesthetic movement of related
variables. Reports include feeling sensations in the hands or feet,
coupled with visualizations of shapes or objects, when analyzing
mathematical equations, physical systems, or music. In another case, a
person described seeing interactions between physical shapes causing
sensations in the feet when solving a math problem. Generally, those
with this type of synesthesia can memorize and visualize complicated
systems, and with a high degree of accuracy, predict the results of
changes to the system. Examples include predicting the results of
computer simulations in subjects such as quantum mechanics or fluid
dynamics when results are not naturally intuitive.
Other forms
Other
forms of synesthesia have been reported, but little has been done to
analyze them scientifically. There are at least 80 types of synesthesia.
In August 2017 a research article in the journal Social Neuroscience reviewed studies with fMRI to determine if persons who experience autonomous sensory meridian response
are experiencing a form of synesthesia. While a determination has not
yet been made, there is anecdotal evidence that this may be the case,
based on significant and consistent differences from the control group,
in terms of functional connectivity within neural pathways. It is
unclear whether this will lead to ASMR being included as a form of
existing synesthesia, or if a new type will be considered.
Signs and symptoms
Some
synesthetes often report that they were unaware their experiences were
unusual until they realized other people did not have them, while others
report feeling as if they had been keeping a secret their entire lives.
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, many synesthetes themselves do not
perceive their synesthetic experiences as a handicap. On the contrary,
some report it as a gift—an additional "hidden" sense—something they
would not want to miss. Most synesthetes become aware of their
distinctive mode of perception in their childhood. Some have learned how
to apply their ability in daily life and work. Synesthetes have used
their abilities in memorization of names and telephone numbers, mental
arithmetic, and 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 in synesthesia research. Some synesthetes report that vowels are more strongly colored, while for others consonants are more strongly colored.
Self reports, interviews, and autobiographical notes by synesthetes
demonstrate a great degree of variety in types of synesthesia, intensity
of synesthetic perceptions, awareness of the perceptual discrepancies
between synesthetes and non-synesthetes, and the ways synesthesia is
used in work, creative processes, and daily life.
Synesthetes are very likely to participate in creative activities.
It has been suggested that individual development of perceptual and
cognitive skills, in addition to one's cultural environment, produces
the variety in awareness and practical use of synesthetic phenomena.
Synesthesia may also give a memory advantage. In one study, conducted
by Julia Simner of the University of Edinburgh, it was found that
spatial sequence synesthetes have a built-in and automatic mnemonic
reference. So the non-synesthete will need to create a mnemonic device
to remember a sequence (like dates in a diary), but the synesthete can
simply reference their spatial visualizations.
Mechanism
Regions thought to be cross-activated in grapheme-color synesthesia (green=grapheme recognition area, red=
V4 color area)
As of 2015, the neurological correlates of synesthesia had not been established.
Dedicated regions of the brain are specialized for given
functions. Increased cross-talk between regions specialized for
different functions may account for the many types of synesthesia. For
example, the additive experience of seeing color when looking at
graphemes might be due to cross-activation of the grapheme-recognition
area and the color area called V4 (see figure).
This is supported by the fact that grapheme-color synesthetes are able
to identify the color of a grapheme in their peripheral vision even when
they cannot consciously identify the shape of the grapheme.
An alternative possibility is disinhibited feedback, or a
reduction in the amount of inhibition along normally existing feedback
pathways.
Normally, excitation and inhibition are balanced. However, if normal
feedback were not inhibited as usual, then signals feeding back from
late stages of multi-sensory processing might influence earlier stages
such that tones could activate vision. Cytowic and Eagleman find support
for the disinhibition idea in the so-called acquired forms of synesthesia that occur in non-synesthetes under certain conditions: temporal lobe epilepsy, head trauma, stroke, and brain tumors. They also note that it can likewise occur during stages of meditation, deep concentration, sensory deprivation, or with use of psychedelics such as LSD or mescaline, and even, in some cases, marijuana. However, synesthetes report that common stimulants, like caffeine and cigarettes do not affect the strength of their synesthesia, nor does alcohol.
A very different theoretical approach to synesthesia is that based on ideasthesia. According to this account, synesthesia is a phenomenon mediated by the extraction of the meaning of the inducing stimulus. Thus, synesthesia may be fundamentally a semantic
phenomenon. Therefore, to understand neural mechanisms of synesthesia
the mechanisms of semantics and the extraction of meaning need to be
understood better. This is a non-trivial issue because it is not only a
question of a location in the brain at which meaning is "processed" but
pertains also to the question of understanding—epitomized in e.g., the Chinese room problem. Thus, the question of the neural basis of synesthesia is deeply entrenched into the general mind–body problem and the problem of the explanatory gap.
Genetics
The genetic mechanism of synesthesia has long been debated. Due to
the prevalence of synesthesia among the first-degree relatives of
synesthetes, there is evidence that synesthesia might have a genetic basis, however the monozygotic twins case studies indicate there is an epigenetic component. Synesthesia might also be an oligogenic condition, with locus heterogeneity,
multiple forms of inheritance (including Mendelian in some cases), and
continuous variation in gene expression. It has been found that women
have a higher chance of developing Synesthesia, and in the UK, females
are 8 times more likely to have it than men (reasons are unknown). When
people are left-handed it is inherited, and researchers have discovered
that synesthetes have a higher probability of being left-handed than the
general population.
Diagnosis
Although often termed a "neurological condition," synesthesia is not listed in either the DSM-IV or the ICD since it usually does not interfere with normal daily functioning. Indeed, most synesthetes report that their experiences are neutral or even pleasant. Like perfect pitch, synesthesia is simply a difference in perceptual experience.
Reaction
times for answers that are congruent with a synesthete's automatic
colors are shorter than those whose answers are incongruent.
Synesthesia Test Variations
A number of tests exist for synesthesia. Each common type has a
specific test. When testing for grapheme-color synesthesia a visual test
is given. The person is shown a picture that includes black letters and
numbers. A synesthete will associate the letters and numbers with a
specific color. An auditory test is another way to test for synesthesia.
A sound is turned on and one will either identify it with a taste, or
envision shapes. The audio test correlates with chromesthesia (sounds
with colors). Since people question whether or not synesthesia is tied
to memory the "retest" is given. One is given a set of objects and is
asked to assign colors, tastes, personalities, or more. After a period
of time, the same objects are presented and the person is asked again to
do the same task. The synesthete is able to assign the same
characteristics, because that person has permanent neural associations
in the brain, rather than memories of a certain object. The simplest
approach is test-retest reliability over long periods of time, using
stimuli of color names, color chips, or a computer-screen color picker
providing 16.7 million choices. Synesthetes consistently score around
90% on reliability of associations, even with years between tests.
In contrast, non-synesthetes score just 30–40%, even with only a few
weeks between tests and a warning that they would be retested.
The automaticity of synesthetic experience. A synesthete might perceive the left panel like the panel on the right.
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 is a great variety in types of synesthesia, and
within each type, individuals report differing triggers for their
sensations and differing intensities of experiences. This variety means
that defining synesthesia in an individual is difficult, and the
majority of synesthetes are completely unaware that their experiences
have a name.
Neurologist Richard Cytowic identifies the following diagnostic criteria for synesthesia in his first edition book. However, the criteria are different in the second book:
- Synesthesia is involuntary and automatic.
- Synesthetic perceptions are spatially extended, meaning they often
have a sense of "location." For example, synesthetes speak of "looking
at" or "going to" a particular place to attend to the experience.
- Synesthetic percepts are consistent and generic (i.e., simple rather than pictorial).
- Synesthesia is highly memorable.
- Synesthesia is laden with affect.
Cytowic's early cases mainly included individuals whose synesthesia
was frankly projected outside the body (e.g., on a "screen" in front of
one's face). Later research showed that such stark externalization
occurs in a minority of synesthetes. Refining this concept, Cytowic and Eagleman
differentiated between "localizers" and "non-localizers" to distinguish
those synesthetes whose perceptions have a definite sense of spatial
quality from those whose perceptions do not.
Prevalence
Estimates
of prevalence of synesthesia have ranged widely, from 1 in 4 to 1 in
25,000 - 100,000. However, most studies have relied on synesthetes
reporting themselves, introducing self-referral bias. In what is cited as the most accurate prevalence study so far,
self-referral bias was avoided by studying 500 people recruited from
the communities of Edinburgh and Glasgow Universities; it showed a
prevalence of 4.4%, with 9 different variations of synesthesia.
This study also concluded that one common form of
synesthesia—grapheme-color synesthesia (colored letters and numbers) –
is found in more than one percent of the population, and this latter
prevalence of graphemes-color synesthesia has since been independently
verified in a sample of nearly 3,000 people in the University of
Edinburgh.
The most common forms of synesthesia are those that trigger colors, and the most prevalent of all is day-color.
Also relatively common is grapheme-color synesthesia. We can think of
"prevalence" both in terms of how common is synesthesia (or different
forms of synesthesia) within the population, or how common are different
forms of synesthesia within synesthetes. So within synesthetes, forms
of synesthesia that trigger color also appear to be the most common
forms of synesthesia with a prevalence rate of 86% within synesthetes. In another study, music-color is also prevalent at 18–41%. Some of the rarest are reported to be auditory-tactile, mirror-touch, and lexical-gustatory.
There is research to suggest that the likelihood of having synesthesia is greater in people with autism.
History
The interest in colored hearing dates back to Greek antiquity, when philosophers asked if the color (chroia, what we now call timbre) of music was a quantifiable quality. Isaac Newton proposed that musical tones and color tones shared common frequencies, as did Goethe in his book Theory of Colours. There is a long history of building color organs such as the clavier à lumières on which to perform colored music in concert halls.
In further support of this notion, in Indian classical music, the
musical terms raga and rasa are also synonyms for color and (quality of)
taste, respectively.
The first medical description of "colored hearing" is in an 1812 thesis by the German physician Georg Tobias Ludwig Sachs. The "father of psychophysics," Gustav Fechner, reported the first empirical survey of colored letter photisms among 73 synesthetes in 1876, followed in the 1880s by Francis Galton. Carl Jung refers to "color hearing" in his Symbols of Transformation in 1912.
In the early 1920s, the Bauhaus teacher and musician Gertrud Grunow
researched the relationships between sound, color and movement and
developed a 'twelve-tone circle of colour' which was analogous with the
twelve-tone music of the Austrian composer Arnold Schönberg (1874-1951). She was a participant in at least one of the Congresses for Colour-Sound Research (German:Kongreß für Farbe-Ton-Forschung) held in Hamburg in the late 1920s and early 1930s.
Research into synesthesia proceeded briskly in several countries,
but due to the difficulties in measuring subjective experiences and the
rise of behaviorism, which made the study of any subjective experience taboo, synesthesia faded into scientific oblivion between 1930 and 1980.
As the 1980s cognitive revolution
made inquiry into internal subjective states respectable again,
scientists returned to synesthesia. Led in the United States by Larry
Marks and Richard Cytowic, and later in England by Simon Baron-Cohen and Jeffrey Gray,
researchers explored the reality, consistency, and frequency of
synesthetic experiences. In the late 1990s, the focus settled on
grapheme → color synesthesia, one of the most common
and easily studied types. Psychologists and neuroscientists study
synesthesia not only for its inherent appeal, but also for the insights
it may give into cognitive and perceptual processes that occur in
synesthetes and non-synesthetes alike. Synesthesia is now the topic of
scientific books and papers, PhD theses, documentary films, and even
novels.
Since the rise of the Internet in the 1990s, synesthetes began
contacting one another and creating web sites devoted to the condition.
These rapidly grew into international organizations such as the American Synesthesia Association, the UK Synaesthesia Association,
the Belgian Synesthesia Association, the Canadian Synesthesia
Association, the German Synesthesia Association, and the Netherlands
Synesthesia Web Community.
Society and culture
Notable cases
Solomon Shereshevsky, a newspaper reporter turned celebrated mnemonist, was discovered by Russian neuropsychologist, Alexander Luria, to have a rare fivefold form of synesthesia. Words and text were not only associated with highly vivid visuo-spatial imagery but also sound, taste, color, and sensation.
Shereshevsky could recount endless details of many things without form,
from lists of names to decades-old conversations, but he had great
difficulty grasping abstract concepts. The automatic, and nearly
permanent, retention of every detail due to synesthesia greatly
inhibited Shereshevsky's ability to understand what he read or heard.
Neuroscientist and author V.S. Ramachandran
studied the case of a grapheme-color synesthete who was also color
blind. While he couldn't see certain colors with his eyes, he could
still "see" those colors when looking at certain letters. Because he
didn't have a name for those colors, he called them "Martian colors."
Art
Other notable synesthetes come particularly from artistic professions
and backgrounds. Synesthetic art historically refers to multi-sensory
experiments in the genres of visual music, music visualization, audiovisual art, abstract film, and intermedia.
Distinct from neuroscience, the concept of synesthesia in the arts is
regarded as the simultaneous perception of multiple stimuli in one gestalt experience.
Neurological synesthesia has been a source of inspiration for artists, composers, poets, novelists, and digital artists. Vladimir Nabokov writes explicitly about synesthesia in several novels. Wassily Kandinsky (a synesthete) and Piet Mondrian (not a synesthete) both experimented with image-music congruence in their paintings. Alexander Scriabin composed colored music that was deliberately contrived and based on the circle of fifths, whereas Olivier Messiaen invented a new method of composition (the modes of limited transposition) specifically to render his bi-directional sound-color synesthesia. For example, the red rocks of Bryce Canyon are depicted in his symphony Des canyons aux étoiles...
("From the Canyons to the Stars"). New art movements such as literary
symbolism, non-figurative art, and visual music have profited from
experiments with synesthetic perception and contributed to the public
awareness of synesthetic and multi-sensory ways of perceiving.
Contemporary artists with synesthesia, such as Carol Steen and Marcia Smilack
(a photographer who waits until she gets a synesthetic response from
what she sees and then takes the picture), use their synesthesia to
create their artwork. Brandy Gale, a Canadian visual artist, experiences
an involuntary joining or crossing of any of her senses – hearing,
vision, taste, touch, smell and movement. Gale paints from life rather
than from photographs and by exploring the sensory panorama of each
locale attempts to capture, select, and transmit these personal
experiences.
David Hockney
perceives music as color, shape, and configuration and uses these
perceptions when painting opera stage sets (though not while creating
his other artworks). Kandinsky combined four senses: color, hearing,
touch, and smell. Nabokov described his grapheme-color synesthesia at length in his autobiography, Speak, Memory, and portrayed it in some of his characters.
In addition to Messiaen, whose three types of complex colors are
rendered explicitly in musical chord structures that he invented, other composers who reported synesthesia include Duke Ellington, Rimsky-Korsakov, and Jean Sibelius. Michael Torke is a contemporary example of a synesthetic composer. Physicist Richard Feynman describes his colored equations in his autobiography, What Do You Care What Other People Think?
Other notable synesthetes include musicians Billy Joel, Itzhak Perlman, Alexander Frey, Lorde, Brendon Urie, Ida Maria, Brian Chase and Patrick Stump; inventor Nikola Tesla; electronic musician Richard D. James a.k.a. Aphex Twin (who claims to be inspired by lucid dreams as well as music); and classical pianist Hélène Grimaud. Drummer Mickey Hart of The Grateful Dead wrote about his experiences with synaesthesia in his autobiography Drumming at the Edge of Magic. Pharrell Williams, of the groups The Neptunes and N.E.R.D., also experiences synesthesia and used it as the basis of the album Seeing Sounds. Singer/songwriter Marina and the Diamonds experiences music → color synesthesia and reports colored days of the week.
Some artists frequently mentioned as synesthetes did not, in fact, have the neurological condition. Scriabin's 1911 Prometheus, for example, is a deliberate contrivance whose color choices are based on the circle of fifths and appear to have been taken from Madame Blavatsky. The musical score has a separate staff marked luce whose "notes" are played on a color organ. Technical reviews appear in period volumes of Scientific American.
On the other hand, his older colleague Rimsky-Korsakov (who was
perceived as a fairly conservative composer) was, in fact, a synesthete.
French poets Arthur Rimbaud and Charles Baudelaire wrote of synesthetic experiences, but there is no evidence they were synesthetes themselves. Baudelaire's 1857 Correspondances
introduced the notion that the senses can and should intermingle.
Baudelaire participated in a hashish experiment by psychiatrist Jacques-Joseph Moreau and became interested in how the senses might affect each other. Rimbaud later wrote Voyelles (1871), which was perhaps more important than Correspondances in popularizing synesthesia. He later boasted "J'inventais la couleur des voyelles!" (I invented the colors of the vowels!).
Daniel Tammet wrote a book on his experiences with synesthesia called Born on a Blue Day.
Joanne Harris, author of Chocolat, is a synesthete who says she experiences colors as scents. Her novel Blueeyedboy features various aspects of synesthesia.
Ramin Djawadi, a composer best known for his work on composing the theme songs and scores for such TV series as Game of Thrones, Westworld and for the Iron Man movie, also has synesthesia. He says he tends to "associate colors with music, or music with colors."
Literature
Synesthesia is sometimes used as a plot device or way of developing a character's inner life. Author and synesthete Pat Duffy describes four ways in which synesthetic characters have been used in modern fiction.
- Synesthesia as Romantic
ideal: in which the condition illustrates the Romantic ideal of
transcending one's experience of the world. Books in this category
include The Gift by Vladimir Nabokov.
- Synesthesia as pathology: in which the trait is pathological. Books in this category include The Whole World Over by Julia Glass.
- Synesthesia as Romantic pathology: in which synesthesia is
pathological but also provides an avenue to the Romantic ideal of
transcending quotidian experience. Books in this category include Holly Payne’s The Sound of Blue and Anna Ferrara's The Woman Who Tried To Be Normal.
- Synesthesia as psychological health and balance: Painting Ruby Tuesday by Jane Yardley, and A Mango-Shaped Space by Wendy Mass.
Many literary depictions of synesthesia are not accurate. Some say
more about an author's interpretation of synesthesia than the phenomenon
itself.
Research
Tests
like this demonstrate that people do not attach sounds to visual shapes
arbitrarily. When people are given a choice between the words "Bouba"
and "Kiki", the left shape is almost always called "Kiki" while the
right is called "Bouba"
Research on synesthesia raises questions about how the brain combines
information from different sensory modalities, referred to as crossmodal perception or multisensory integration.
An example of this is the bouba/kiki effect. In an experiment first designed by Wolfgang Köhler, people are asked to choose which of two shapes is named bouba and which kiki. The angular shape, kiki, is chosen by 95–98% and bouba for the rounded one. Individuals on the island of Tenerife showed a similar preference between shapes called takete and maluma. Even 2.5-year-old children (too young to read) show this effect. Research indicated that in the background of this effect may operate a form of ideasthesia.
Researchers hope that the study of synesthesia will provide better understanding of consciousness and its neural correlates. In particular, synesthesia might be relevant to the philosophical problem of qualia,
given that synesthetes experience extra qualia (e.g., colored sound).
An important insight for qualia research may come from the findings that
synesthesia has the properties of ideasthesia, which then suggest a crucial role of conceptualization processes in generating qualia.
Technological applications
Synesthesia also has a number of practical applications, one of which is the use of 'intentional synesthesia' in technology.
The Voice (vOICe)
Peter Meijer developed a sensory substitution device for the visually impaired
called The vOICe (the capital letters "O," "I," and "C" in "vOICe" are
intended to evoke the expression "Oh I see"). The vOICe is a privately
owned research project, running without venture capital, that was first
implemented using low-cost hardware in 1991.
The vOICe is a visual-to-auditory sensory substitution device (SSD)
preserving visual detail at high resolution (up to 25,344 pixels).
The device consists of a laptop, head-mounted camera or computer
camera, and headphones. The vOICe converts visual stimuli of the
surroundings captured by the camera into corresponding aural
representations (soundscapes)
delivered to the user through headphones at a default rate of one
soundscape per second. Each soundscape is a left-to-right scan, with
height represented by pitch, and brightness by loudness.
The vOICe compensates for the loss of vision by converting information
from the lost sensory modality into stimuli in a remaining modality.
