Synaesthesia is an unusual and intriguing condition sometimes described as a 'mixing of the senses'. People with synaesthesia have experiences in which their senses appear to be connected. While some synaesthetes associate letters, days of the week, or months of the year with colours, others feel a taste on their tongue when they say a word, or experience vivid sensations that incorporate colours, shapes, textures and movement in response to hearing music. Synaesthesia is different from normal memories or associations because the sensations experienced are automatic and involuntary, and are largely consistent over time. The current estimates are that 2-5% of people have synaesthetic experiences.
Synaesthesia is a neurodevelopmental condition, which means that it results from events during brain development, leading to unusual patterns of neural connectivity. Brain imaging studies show that something different is happening in the brains of synaesthetes compared to non-synaesthetes when they are exposed to stimuli that trigger their synaesthesia. Synaesthesia runs in families, suggesting that there is a strong genetic basis for these alterations in brain development, but very little is known about which genes are responsible for this.
We are applying the latest genomic methods to search for molecular genetic clues and to investigate overlaps with other brain-related traits. Our work includes next-generation DNA sequencing in extended families where multiple relatives are synaesthetic, across successive generations, to search for rare gene variants that could have large effects on the trait. In a complementary approach, we are recruiting large numbers of unrelated people with synaesthesia, to support genome-wide association screening.
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- Example publications
Tilot, A. K., Kucera, K. S., Vino, A., Asher, J. E., Baron-Cohen, S., & Fisher, S. E. (2018). Rare variants in axonogenesis genes connect three families with sound–color synesthesia. Proceedings of the National Academy of Sciences of the United States of America, 115(12), 3168-3173. doi:10.1073/pnas.1715492115. [pdf]
Baron-Cohen, S., Johnson, D., Asher, J. E., Wheelwright, S., Fisher, S. E., Gregersen, P. K., & Allison, C. (2013). Is synaesthesia more common in autism? Molecular Autism, 4(1): 40. doi:10.1186/2040-2392-4-40. [pdf]
Gregersen, P. K., Kowalsky, E., Lee, A., Baron-Cohen, S., Fisher, S. E., Asher, J. E., Ballard, D., Freudenberg, J., & Li, W. (2013). Absolute pitch exhibits phenotypic and genetic overlap with synesthesia. Human Molecular Genetics, 22, 2097-2104. doi:10.1093/hmg/ddt059. [pdf]
- What is it like to experience synaesthesia?
Synaesthesia is not a disorder, but rather a different way of experiencing the world. People with synaesthesia are usually not bothered by their sensory associations and often say that it is fun to think of letters in colours or taste words. Many feel that their synaesthesia enhances their world, although some people find otherwise neutral occurrences to have unusual negative associations. The following quote is from a synaesthete describing her experiences:
All of my life I've experienced smelly words that also taste bad; pleasant smelling words that taste good; colors for aromas and visual music....Imagine being a preschooler and just hating the word "soak" in any tense/form because it was "an ugly, nasty word that smells bad." Imagine being 8 and when your class is doing a unit on Greece having an adverse reaction to the word "Parthenon" because it smells like diarrhea and had a hideous sound. (I still detest that word and anything that has "parth" in it)... When I was a young child, I took the expression "left a bad taste in one's mouth" literally, thinking that the speaker came across a word that tasted bad like "soak." How I truly hate that word!
- Famous individuals who experienced synaesthesia
Did you know that many notable historical figures in the arts experienced synaesthesia? Actress Marilyn Monroe, composer Jean Sibelius and Dutch artist Vincent van Gogh are all reported as experiencing synaesthesia. Many contemporary figures have also described synaesthesia. Accomplished songwriter and Actress Mary J Blige reported in a 2013 interview that she sees “music in colors”. In her 2005 autobiography: Tori Amos: Piece by Piece, the singer-songwriter describes synaesthesia as “…the best kaleidoscope ever.” Rock and roll hall-of-famer Billy Joel described his synaesthesia to the magazine Psychology Today. However, it is not just musicians that experienced synaesthesia. Many visual artists also report synaesthesia.
- Further sources of information
Some information on synaesthesia:
Recommended books to read:
The Frog who Croaked Blue: Synesthesia and the Mixing of the Senses by Jamie Ward.The Oxford Handbook of Synesthesia edited by Julia Simner and Edward Hubbard.Wednesday is Indigo Blue: Discovering the Brain of Synesthesia by Richard Cytowic and David Eagleman.