History of synesthesia research

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Synesthesia is a neurological condition in which two or more bodily senses are coupled. For example, in a form of synesthesia known as grapheme-color synesthesia, letters or numbers may be perceived as inherently colored. Historically, the most commonly described form of synesthesia (or synesthesia-like mappings) has been between sound and vision, e.g. the hearing of colors in music.

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Early investigations of colored hearing

The interest in colored hearing, i.e. the co-perception of color 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. [1] The seventeenth-century physicist Isaac Newton tried to solve the problem by assuming that musical tones and colour tones have frequencies in common. [2] 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. [2] [3] (For more information, see the synesthesia in art page).

John Locke in An Essay Concerning Human Understanding (1689) reports:

A studious blind man, who had mightily beat his head about visible objects, and made use of the explication of his books and friends, to understand those names of light and colours which often came in his way, bragged one day, That he now understood what scarlet signified. Upon which, his friend demanding what scarlet was? The blind man answered, It was like the sound of a trumpet.

Locke, An Essay Concerning Human Understanding [4]

Whether this is an actually synesthesia, or simply reflects metaphorical speech, is debated. [5] [6] A similar example appears in Leibniz's New Essays on Human Understanding (written in 1704, but not published until 1764); indeed given that the New Essays is intended as a rebuttal to Locke, it may even have been the same individual. Although it is mainly speculation, there is reason to believe that the person Locke referred to was the mathematician and scientist Nicholas Saunderson, who held the Lucasian professor chair at Cambridge University, and whose general prominence would have made his statements noticeable. In Letters on the blind, Denis Diderot, one of Locke's followers, mentions Saunderson by name in related philosophical reflections.

In 1710, Thomas Woolhouse reported the case of another blind man who perceived colors in response to sounds. [7] Numerous other philosophers and scientists, including Isaac Newton (1704), Erasmus Darwin (1790) and Wilhelm Wundt (1874) may have referred to synesthesia, or at least synesthesia-like mappings between colors and musical notes. Henry David Thoreau remarked in a letter to Ralph Waldo Emerson in 1848 that a child he knew had asked him "if I did not use ‘colored words.’ She said that she could tell the color of a great many words, and amused the children at school by so doing." [8]

19th century investigations

The first agreed upon account of synesthesia comes from German physician Georg Tobias Ludwig Sachs in 1812, who reports on his colored vowels as part of his PhD dissertation (on his albinism), [5] [9] although its importance has only become apparent retrospectively. [10] [6] The father of psychophysics, Gustav Fechner reported on a first empirical survey of colored letter photisms among 73 synesthetes in 1871, [11] [12] followed in the 1880s by Francis Galton. [13] [14] [15] These early investigations aroused little interest, and the phenomenon was first brought to the attention of the scientific community. Research into synesthesia proceeded briskly, with researchers from England, Germany, France and the United States all investigating the phenomenon. These early research years corresponded with the founding of psychology as a scientific field (see history of psychology). By 1926, Mahling cites 533 published papers dealing with colored hearing (or hearing → color synesthesia) alone. [7]

Although there is still debate as to when the first international academic conference to seriously look at synesthesia took place, a likely candidate is the following: From 2 – 5 March 1927, Georg Anschütz (who was once a student of Alfred Binet) presided over the convening of the first Kongresse zur Farbe-Ton-Forschung (Congress for Color-Tone Research), in Hamburg, Germany. A second congress took place 1 – 5 October 1930, in Hamburg, Germany; [16] the third from 2 – 7 October 1933; and the 4th and final conference in this series took place 4 – 10 October 1936. [17]

In addition to drawing concerted scientific interest, the phenomenon of synesthesia started arousing interest in the salons of fin de siecle Europe. The French Symbolist poets Arthur Rimbaud and Charles Baudelaire wrote poems which focused on synesthetic experience. Baudelaire's Correspondances (1857) (full text available here) introduced the Romantic notion that the senses can and should intermingle. Kevin Dann argues that Baudelaire probably learned of synesthesia from reading medical textbooks that were available in his home, [18] and it is generally agreed that neither Baudelaire, nor Rimbaud were true synesthetes. Rimbaud, following Baudelaire, wrote Voyelles (1871) (full text available here) which was perhaps more important than Correspondances in popularizing synesthesia. Numerous other composers, artists and writers followed suit, making synesthesia well known among the artistic community of the day.

Due to the difficulties in assessing and measuring subjective internal experiences, and the rise of behaviorism in psychology, which banished any mention of internal experiences, the study of synesthesia gradually waned during the 1930s. Marks [7] lists 44 papers discussing colored hearing from 1900 to 1940, while in the following 35 years from 1940 to 1975, only 12 papers were published on this topic. Cretien van Campen graphed the number of publications in the period 1780 - 2000 and noticed a revival of synesthesia studies from the 1980s. [19]

Modern research

In the 1980s, as the cognitive revolution had begun to make discussion of internal states and even the study of consciousness respectable again, scientists began to once again examine this fascinating phenomenon. Led by Lawrence E. Marks [7] and Richard Cytowic [20] [21] in the United States, and by Simon Baron-Cohen and Jeffrey Gray [22] in England, research into synesthesia began by exploring the reality, consistency and frequency of synesthetic experiences. In the late 1990s, researchers began to turn their attention towards grapheme-color synesthesia, one of the most common [23] [24] and easily studied forms of synesthesia. In 2006, the journal Cortex published a special issue on synesthesia, composed of 26 articles from individual case reports to functional neuroimaging studies of the neural basis of synesthesia. Synesthesia has been the topic of several recent scientific books and novels and a recent short film has even included characters who experience synesthesia (for more information, see the main synesthesia page).

Mirroring these developments in the professional community, synesthetes and synesthesia researchers have come together to found several societies dedicated to research and education about synesthesia, its consequences and uses. In 1995, the American Synesthesia Association was founded, and has been having annual meetings since 2001. In England, the UK Synaesthesia Association, arose out of a similar desire to bring together synesthetes and the people who study them, and has held two conferences (in 2005 and 2006). Similarly, since its inception in 1993, Sean A. Day has administered the "synesthesia list", an e-mail list for synesthetes and researchers around the world. With increased scientific knowledge and public outreach, awareness of this condition is growing worldwide.

See also

Related Research Articles

The clavier à lumières, or tastiera per luce, as it appears in the score, was a musical instrument invented by Alexander Scriabin for use in his work Prometheus: Poem of Fire. Only one version of this instrument was constructed, for the performance of Prometheus: Poem of Fire in New York City in 1915. The instrument was supposed to be a keyboard, with notes corresponding to colors as given by Scriabin's synesthetic system, specified in the score. However, numerous synesthesia researchers have cast doubt on the claim that Scriabin was a synesthete.

<i>The Man Who Tasted Shapes</i> Book by Richard Cytowic

The Man Who Tasted Shapes is a book by neurologist Richard Cytowic about synesthesia.

<span class="mw-page-title-main">Number form</span> Mental map of numbers

A number form is a mental map of numbers, which automatically and involuntarily appears whenever someone who experiences number-forms thinks of numbers. Numbers are mapped into distinct spatial locations and the mapping may be different across individuals. Number forms were first documented and named by Sir Francis Galton in his The Visions of Sane Persons. Later research has identified them as a type of synesthesia.

<span class="mw-page-title-main">Grapheme–color synesthesia</span> Synesthesia that associates numbers or letters with colors

Grapheme–color synesthesia or colored grapheme synesthesia is a form of synesthesia in which an individual's perception of numerals and letters is associated with the experience of colors. Like all forms of synesthesia, grapheme–color synesthesia is involuntary, consistent and memorable. Grapheme–color synesthesia is one of the most common forms of synesthesia and, because of the extensive knowledge of the visual system, one of the most studied.

Ordinal-linguistic personification is a form of synesthesia in which ordered sequences, such as ordinal numbers, days, months and letters are associated with personalities or genders. Although this form of synesthesia was documented as early as the 1890s, researchers have, until recently, paid little attention to this form.

Lexical–gustatory synesthesia is a rare form of synesthesia in which spoken and written language causes individuals to experience an automatic and highly consistent taste/smell. The taste is often experienced as a complex mixture of both temperature and texture. For example, in a particular synaesthete, JIW, the word jail would taste of cold, hard bacon. Synesthetic tastes are evoked by an inducer/concurrent complex. The inducer is the stimulus that activates the sensation and the taste experience is the concurrent.

The phrase synesthesia in art has historically referred to a wide variety of artists' experiments that have explored the co-operation of the senses in the genres of visual music, music visualization, audiovisual art, abstract film, and intermedia. 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 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 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 have scientific methods become available to assess synesthesia in persons. For synesthesia in artists before that time one has to interpret (auto)biographical information. For instance, there has been debate on the neurological synesthesia of historical artists like Kandinsky and Scriabin. Additionally, Synesthetic art may refer to either art created by synesthetes or art created to elicit synesthetic experience in the general audience.

Synesthesia is a neurological condition in which two or more bodily senses are coupled. For example, in a form of synesthesia known as Grapheme → color synesthesia, letters or numbers may be perceived as inherently colored. In another, called number → form synesthesia, numbers are automatically and consistently associated with locations in space. In yet another form of synesthesia, called ordinal linguistic personification, either numbers, days of the week, or months of the year evoke personalities. In other forms of synesthesia, music and other sounds may be perceived as colored or having particular shapes. Recent research has begun to explore the neural basis of these experiences, drawing both on neuroscientific principles and on functional neuroimaging data.

Fictional works that have main characters with synesthesia and non-fiction books to non-specialist audiences reflect the condition's influence in popular culture and how non-synesthetes view it. Synesthesia is a neurological condition in which one or more sensory modalities become linked. However, for over a century, synesthesia has also been the artistic and poetic devices that try to connect the senses.

<span class="mw-page-title-main">Chromesthesia</span> Sound to color synesthesia

Chromesthesia or sound-to-color synesthesia is a type of synesthesia in which sound involuntarily evokes an experience of color, shape, and movement. Individuals with sound-color synesthesia are consciously aware of their synesthetic color associations/perceptions in daily life. Synesthetes that perceive color while listening to music experience the colors in addition to the normal auditory sensations. The synesthetic color experience supplements, but does not obscure real, modality-specific perceptions. As with other forms of synesthesia, individuals with sound-color synesthesia perceive it spontaneously, without effort, and as their normal realm of experience. Chromesthesia can be induced by different auditory experiences, such as music, phonemes, speech, and/or everyday sounds.

Synesthesia 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. There are many occurrences of synesthesia in books, television and film.

<span class="mw-page-title-main">Synesthesia</span> Neurological condition involving the crossing of senses

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. For instance, people with synesthesia may experience colors when listening to music, see shapes when smelling certain scents, or perceive tastes when looking at words. People who report a lifelong history of such experiences are known as synesthetes. Awareness of synesthetic perceptions varies from person to person with the perception of synesthesia differing based on an individual's unique life experiences and the specific type of synesthesia that they have. 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, or may appear as a three-dimensional map. Synesthetic associations can occur in any combination and any number of senses or cognitive pathways.

<span class="mw-page-title-main">Cretien van Campen</span>

Cretien van Campen is a Dutch 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 | SCP. He is best known for his work on synesthesia and studies of quality of life.

<span class="mw-page-title-main">Richard Cytowic</span> American neurologist and author

Richard E. Cytowic is an American neurologist and author who rekindled interest in synesthesia in the 1980s and returned it to mainstream science. He was nominated for the Pulitzer Prize for his New York Times Magazine cover story about James Brady, the Presidential Press Secretary shot in the brain during the assassination attempt on President Reagan. Cytowic’s writing ranges from textbooks and music reviews, to his Metro Weekly "Love Doctor" essays and brief medical biographies of Anton Chekhov, Maurice Ravel and Virginia Woolf. His work is the subject of two BBC Horizon documentaries, “Orange Sherbert Kisses” (1994) and “Derek Tastes of Earwax” (2014).

<i>Wednesday Is Indigo Blue</i> Book by Richard Cytowic

Wednesday Is Indigo Blue: Discovering the Brain of Synesthesia is a 2009 non-fiction book written by Richard Cytowic and David Eagleman documenting the current scientific understanding of synesthesia, a perceptual condition where an experience of one sense causes an automatic and involuntary experience in another sense. The afterword is written by Dimitri Nabokov, a synesthete, and the son of the well-known author and synesthete Vladimir Nabokov.

Carol Steen is an artist, writer and curator who lives and works in New York. She has had over 20 solo gallery exhibitions, her first solo exhibition in 1973 was at the Detroit Institute of Arts, and her work has been in over 50 group exhibitions including shows at the Philadelphia Museum of Art, the Brookgreen Gardens Museum in South Carolina, the Cranbrook Museum in Michigan, and the DeCordova Museum in Massachusetts. Steen's work has also been exhibited at the Theatre for a New Audience in Brooklyn, NY, the Museum of Modern Art of Ukraine, and Wayne State University, Detroit, Michigan.

<span class="mw-page-title-main">Ideasthesia</span> Phenomenon in which concepts evoke sensory experiences

Ideasthesia is a neuropsychological phenomenon in which activations of concepts (inducers) evoke perception-like sensory experiences (concurrents). The name comes from the Ancient Greek ἰδέα and αἴσθησις, meaning 'sensing concepts' or 'sensing ideas'. The notion was introduced by neuroscientist Danko Nikolić as an alternative explanation for a set of phenomena traditionally covered by synesthesia.

Mirror-touch synesthesia is a rare condition which causes individuals to experience a similar sensation in the same part or opposite part of the body that another person feels. For example, if someone with this condition were to observe someone touching their cheek, they would feel the same sensation on their own cheek. Synesthesia, in general, is described as a condition in which a concept or sensation causes an individual to experience an additional sensation or concept. Synesthesia is usually a developmental condition; however, recent research has shown that mirror touch synesthesia can be acquired after sensory loss following amputation.

The genetic mechanism of synesthesia has long been debated, with researchers previously claiming it was a single X-linked trait due to seemingly higher prevalence in women and no evidence of male-male transmission This is where the only synesthetic parent is male and the male child has synesthesia, meaning that the trait cannot be solely linked to the X chromosome.

References

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