History of synesthesia research

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.

Early historical mentions

The earliest mentions of synesthesia are debated. Although it is well established that Pythagoras referred to the music of the spheres, whether this early mention refers to synesthesia or rather to a metaphorical/mystical interpretation of mathematical harmonies is unclear.

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

Again, whether this is an actual instance of synesthesia, or simply reflects metaphorical speech, is debated. 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 Woodhouse reported the case of another blind man who perceived colors in response to sounds (see Harvnb|Marks|1975). The first agreed upon account of synesthesia comes from Sachs in 1812, who reports on his colored vowels as part of his PhD dissertation (on his albinism), although its importance has only become apparent restrospectively.

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. Indeed, the father of psychophysics, Gustav Fechner reported a case of colored vowels in 1876 (see Harvnb|Marks|1975).

Turn of the century investigations

These early investigations aroused little interest, and the phenomenon was first brought to the attention of the scientific community in the 1880s by Francis Galton (Harvnb|Galton|1880a; Harvnb|Galton|1880b; Harvnb|Galton|1883). Following these initial observations, 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 Harv|Marks|1975.

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 March 2nd through 5th of 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 2nd congress took place 1 – 5 October, in Hamburg, Germany; a 3rd October 2 – 7, 1933; and the 4th and final conference in this series took place October 4 – 10, 1936 Harv|Jewanski|1999.

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 " _fr. Correspondances" (1857) ( [http://www.doctorhugo.org/synaesthesia/baudelaire.html full text available here] ) introduced the Romantic notion that the senses can and should intermingle. Kevin Dann Harv|Dann|1998 argues that Baudelaire probably learned of synesthesia from reading medical textbooks that were available in his home, and it is generally agreed that neither Baudelaire, nor Rimbaud were true synesthetes. Rimbaud, following Baudeliare, wrote "Voyelles" (1871) ( [http://www.doctorhugo.org/synaesthesia/rimbaud.html full text available here] ) which was perhaps more important than " _fr. 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 (1975) 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.

The modern renaissance

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 Harv|Marks|1975 and Richard Cytowic (Harvnb|Cytowic|2002 first ed. 1989 Harvnb|Cytowic|2003 first ed. 1993) in the United States, and by Simon Baron-Cohen and Jeffrey Gray (see Harvnb|Baron-Cohen|Harrison|1997) 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 (Harvnb|Day|2005; Harvnb|Rich|Bradshaw|Mattingley|2005) and easily studied forms of synesthesia. In 2006, the journal Cortex published a [http://www.cortex-online.org/cortex.asp?action=toArticles&folderID=176 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 " [http://home.comcast.net/~sean.day/html/the_synesthesia_list.html 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 world-wide.

ee also

*American Synesthesia Association
*UK Synaesthesia Association

References

*Harvard reference
Surname1= Baron-Cohen
Given1= S.
Authorlink1=Simon_Baron_Cohen
Surname2= Harrison
Given2= J. E.
Year=1997
Title= Synaesthesia: Classic and Contemporary Readings
Place= Malden, MA
Publisher= Blackwell
ID=ISBN 0-631-19764-8
URL=

*Harvard reference
Surname1= Cytowic
Given1= R. E.
Year=2002
Title= Synesthesia: A Union of the Senses, 2nd ed
Place= Cambridge, MA
Publisher= MIT Press
ID=ISBN 0-262-03296-1
URL= http://cytowic.net/_Books/_books.html

*Harvard reference
Surname1= Cytowic
Given1= R. E.
Year=2003
Title= The Man Who Tasted Shapes
Place= New York, NY
Publisher= Tarcher/Putnam
ID=ISBN 0-262-53255-7
URL= http://cytowic.net/_Books/_books.html

*Harvard reference
Surname1= Day
Given1= S.A.
Year=2005
Chapter=Some Demographic and Socio-cultural Aspects of Synesthesia
Editor= L. Robertson & N. Sagiv
Title= Synesthesia: Perspectives from Cognitive Neuroscience
Place= Oxford
Publisher= Oxford University Press
Pages= 11-33
ISBN=019516623X
URL=

*Harvard reference
Surname1= Dann
Given1= K. T.
Year=1998
Title= Bright Colors Falsely Seen: Synaesthesia and the Search for Transcendent Knowledge
Publisher= Yale University Press.
ID=ISBN 0-300-06619-8
URL=

*Harvard reference
Surname1= Galton
Given1= F.
Year=1880a
Title= Visualised numerals
Journal= Nature
Issue=
Volume= 21
Pages= 252-256
ID=
URL=

*Harvard reference
Surname1= Galton
Given1= F.
Year=1880b
Title= Visualised numerals
Journal= Nature
Issue=
Volume=22
Pages=494-495
ID=
URL=

*Harvard reference
Surname1= Galton
Given1= F.
Year=1883
Title= Inquiries into Human Faculty and its Development
Place= London
Publisher= Dent & Sons
ID=
URL=

*Harvard reference
Surname1= Jewanski
Given1= Jörg
Year= 1999
Title= Ist C = Rot?
Place= Sinzig
Publisher= Studio
ID=
URL=

*Harvard reference
Surname1= Marks
Given1= L.E.
Year=1975
Title= On colored-hearing synesthesia: Cross-modal translations of sensory dimensions
Journal= Psychological Bulletin
Issue=3
Volume=82
Pages=303-331
ID=
URL=

*Harvard reference
Surname1= Rich
Given1= A.N.
Surname2= Bradshaw
Given2= J.L.
Surname3= Mattingley
Given3= J.B.
Year=2005
Title= A systematic, large scale study of synaesthesia: Implications for the role of early experience in lexical-colour associations
Journal= Cognition
Issue=1
Volume=98
Pages=53-84
ID=
URL=