What is synaesthesia?
For synaesthetes, one percept or concept (such as numbers, taste or sound) triggers an experience in another modality (such as touch or smell) (Grossenbacher & Lovelace, 2001). The triggering experience is known as the inducer and the connected experience the concurrent. Usually the inducer and concurrent are in different modalities (such as sound-colour synaesthesia) however this isn’t always the case (such as grapheme-colour synaesthesia where both are visual components).
What senses can synaesthesia involve?
People often think of synaesthesia as a mixing of senses, however it also can involve concepts. Information from all the senses (vision, sound, taste, touch, smell) has been reported in synaesthesia. Many concepts (such as time, letters, numbers, personalities, location) have also been reported. Many variations in inducer-concurrent have been found though some are more common than others. Time-colour (Simner et al., 2006) and perhaps sequence-space (Rothen, Jünemann, Mealor, Burckhardt, & Ward, 2015) are more common and not all combinations of percepts or concepts have been found.
Is synaesthesia genetic?
There is a higher prevalence of synaesthesia in first degree relatives of synaesthetes suggesting a genetic component. Even though synaesthetes’ relatives often also have synaesthesia, the associations (such as the specific letter and colour pairings for grapheme-colour synaesthesia) or type of synaesthesia may differ (Barnett et al., 2008). Preliminary research into genes involved has been conducted, these are only on specific types of synaesthesia though and not yet conclusive (Asher et al., 2008; Tomson et al., 2011). There are also studies pointing to a strong learning component (Witthoft, Winawer, & Eagleman, 2015) therefore synaesthesia appears to be an interaction of genetic predisposition and environment during development.
What is a developmental synaesthete?
Developmental synaesthetes are people who developed synaesthesia during childhood and adolescence. They usually describe themselves as having had synaesthesia “as long as they could remember” (Rich, Bradshaw, & Mattingley, 2005).
Is it possible to have more than one type of synaesthesia?
Yes, it is quite common for synaesthetes to have more than one type of synaesthesia. There are trends relating to how types of synaesthesia cluster, for example someone with grapheme-colour is more likely to have month-colour as a second type than touch-taste (Novich, Cheng, & Eagleman, 2011).
Can synaesthesia be learnt or acquired?
There have been several studies on training grapheme-colour synaesthesia in non-synaesthetes (Bor, Rothen, Schwartzman, Clayton, & Seth, 2014; Colizoli et al., 2016; Colizoli, Murre, & Rouw, 2012; Meier & Rothen, 2009). People can be trained to have grapheme-colour associations and have some conscious phenomenological experiences similar to developmental synaesthetes though this experience generally ends shortly after the training stops. Hallucinogenic drugs can create temporary changes in perceptual experience similar synaesthesia (Luke & Terhune, 2013) however there are marked differences between the phenomenology of drug induced synaesthesia and developmental synaesthesia such as lack of consistency. (We advise not experimenting with hallucinogenic drugs outside of carefully controlled and ethically approved research studies!). Hypnosis can cause temporary synaesthesia like experiences in people highly susceptible to hypnosis though it is debated as to whether this creates behavioural responses similar to developmental synaesthetes (Anderson, Seth, Dienes, & Ward, 2014; Cohen Kadosh, Henik, Catena, Walsh, & Fuentes, 2009; Terhune, Luke, Terhune, Luke, & Kadosh, 2017). There are some cases where people have acquired synaesthesia after sensory deprivation or brain damage (Afra, 2009) though the sensory experiences are generally less rich to that of developmental synaesthetes. Devices have also been created to help people with sensory deprivation such as blindness. One example is to convert pictures into sounds that blind people can learn to interpret (https://www.seeingwithsound.com/). Some people who become experts in using these devices develop synaesthesia like experiences comparable to synaesthesia (Ward & Wright, 2014). Overall, there are many different ways in which temporary experiences similar to synaesthesia have been created however these are not exactly the same as developmental synaesthesia to date.
Do all synaesthetes have the same experiences?
No, the experiences of synaesthetes vary widely. Not only are there many different varieties of synaesthesia reported (80+) the experiences of people with the same type of synaesthesia are also very different (http://www.daysyn.com/Types-of-Syn.html). We describe synaesthesia as idiosyncratic (Grossenbacher & Lovelace, 2001). Two grapheme-colour synaesthetes are likely to have very different grapheme-colour associations. If we look at the associations for a large group of synaesthetes we do however see trends (Simner et al., 2005).
How can I talk to other synaesthetes?
There are synaesthesia groups where people can talk to each other such as those below.
Danish Facebook synaesthesia group (https://www.facebook.com/groups/111409222221125/).
English Facebook synaesthesia group (https://www.facebook.com/groups/2226778430/).
UK Synaesthesia Association Facebook page (https://www.facebook.com/groups/128219365930/).
How can I be kept up to date with synaesthesia news and projects?
Sean Day's International Synaesthesia E-mailing list (to join e-mail firstname.lastname@example.org).
UK Synaesthesia Association E-mailing list (to join email email@example.com).
Facebook pages (see above for “How do I talk to other synaesthetes”).
You can also check the events section of our CCN webpage.
Can I test whether I have synaesthesia?
There are tests and questionnaires which can be used to test or measure whether someone is likely to have synaesthesia. For many types these have not been developed yet though.
SynMap (http://aausynmap.azurewebsites.net/). Grapheme-colour synaesthesia test; alphabets available in English, Danish, Icelandic, Finnish, Chinese, numbers only etc. If you would like a new alphabet added please contact Hazel Anderson (firstname.lastname@example.org).
There used to be a site called the Synesthesia Battery (synesthete.org) which is no longer available.
I am a child with synaesthesia or the parent of a synaesthete and want more information.
It can be difficult for some children when they realise that they experience the world in a slightly different way to non-synaesthetes. Sometimes learning more about synaesthesia can be helpful. About 4% of the population have some type of synaesthesia (Simner et al., 2006) therefore it isn’t as rare as people often think, even knowing that can be helpful.
Advice for parents of synaesthetes (https://www.syntoolkit.org/parent).
List of famous synaesthetes, written by a synaesthesia researcher (http://www.daysyn.com/Famous-synesthetes.html).
Is synaesthesia a condition?
Most synaesthesia researchers consider synaesthesia to be a difference in perceptual experience and not a medical condition. This is because none of the criteria for synaesthesia are negative or necessarily cause problems. Most synaesthetes love their synaesthesia and the slightly different phenomenology they have. There are also benefits to having synaesthesia, see below.
Is synaesthesia associated with autistic spectrum disorder (ASD)?
Only a couple of studies have been conducted on this topic and neither were large scale. There has been some preliminary research suggesting a link between Autism (Baron-Cohen et al., 2013) or Asperger syndrome (Neufeld et al., 2013) and synaesthesia. This is very preliminary and much more research needs to be conducted on this topic before it could be stated that there is a definite link between ASD and synaesthesia. Synaesthesia is a difference in perception not a condition and is very different from ASD.
My synaesthesia is causing me problems.
In very rare instances synaesthetes can have some difficulties associated to their synaesthesia. Some people find the synaesthesia can be quite intense or interfere with their general activities. This is rare however does happen occasionally. Attention has an impact on synaesthesia, generally synaesthetic experiences are lesser when synaesthetes are not attending to the trigger (inducer) of their synaesthesia (such as a grapheme for grapheme-colour synaesthesia, sound for sound-touch synaesthesia etc.) (Sagiv, Heer, & Robertson, 2006). Trying to attend less to the inducing aspect may help to reduce intensity of the synaesthetic experience. If you are having problems associated to your synaesthesia it is advisable to see your Doctor/General Practitioner.
Are there any benefits to synaesthesia?
Synaesthetes have benefits for some specific aspects of memory however the memory improvements are not necessarily connected to the inducer or concurrent linked in their type of synaesthesia. This may be due to general differences in synaesthetes brain structure and the way they process perceptual information (Rothen, Meier, & Ward, 2012). The concurrent information may be integrated with the inducer (such as colours being integrated into grapheme categories) and expertise on these specific pairings could account for memory benefits (Ásgeirsson, Nordfang, & Sørensen, 2015).
Is synaesthesia associated with creativity?
The research suggesting a link between synaesthesia and creativity is mixed. Synaesthetes have some specific benefits however don’t show a general advantage for creativity (Ward, Thompson-Lake, Ely, & Kaminski, 2008). There seem to be a higher synaesthesia prevalence among art students then in the general population (Rothen & Meier, 2010). Many artists use their synaesthesia in their art, below are links to some artistic expressions of synaesthetic experience.
Melissa McCracken, sound-colour synaesthesia (https://www.melissasmccracken.com/ or
Magazine article on artists with synaesthesia by Jacoba Urist (https://www.thecut.com/2016/07/why-do-so-many-artists-have-synesthesia.html).
Where can I find more information?
Sean Day’s website http://www.daysyn.com/index.html
Synaesthesia Toolkit https://www.syntoolkit.org/welcome
University of Sussex Synaesthesia webpage http://www.sussex.ac.uk/synaesthesia/faq
Why is synaesthesia spelt in different ways?
Synaesthesia is spelt with the “a” in UK English (synaesthesia) and without the “a” in US English (synesthesia).
I would like to take part in research.
Many synaesthetes choose to help progress our understanding of synaesthesia by taking part in research projects. These are conducted in academic settings all over the world. Our research group conducts online research as well as in laboratory testing. We get participants in our synaesthesia research to complete some online tests first so that we know more about their experiences. If you are interested in taking part in our online research follow this link for Danish or this link for English (online questionnaires and colour-picker). Calls for participants are often sent in the E-mailing lists and Facebook pages listed previously.
Afra, P. (2009). Acquired auditory-visual synesthesia: A window to early cross-modal sensory interactions. Psychology Research and Behavior Management, 31. https://doi.org/10.2147/PRBM.S4481
Anderson, H. P., Seth, A. K., Dienes, Z., & Ward, J. (2014). Can grapheme-color synesthesia be induced by hypnosis? Frontiers in Human Neuroscience, 8(April), 220. https://doi.org/10.3389/fnhum.2014.00220
Ásgeirsson, Á. G., Nordfang, M., & Sørensen, T. A. (2015). Components of attention in grapheme-color synesthesia: A modeling approach. PLoS ONE, 10(8), 1–19. https://doi.org/10.1371/journal.pone.0134456
Asher, J. E., Lamb, J. A., Brocklebank, D., Cazier, J. B., Maestrini, E., Addis, L., … Monaco, A. P. (2008). A whole-genome scan and fine-mapping linkage study of auditory-visual synesthesia reveals rvidence of linkage to chromosomes 2q24, 5q33, 6p12, and 12p12. American Journal of Human Genetics, 84(2), 279–285. https://doi.org/10.1016/j.ajhg.2009.01.012
Barnett, K. J., Finucane, C., Asher, J. E., Bargary, G., Corvin, A. P., Newell, F. N., & Mitchell, K. J. (2008). Familial patterns and the origins of individual differences in synaesthesia. Cognition, 106(2), 871–93. https://doi.org/10.1016/j.cognition.2007.05.003
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. https://doi.org/10.1186/2040-2392-4-40
Bor, D., Rothen, N., Schwartzman, D. J., Clayton, S., & Seth, A. K. (2014). Adults Can Be Trained to Acquire Synesthetic Experiences. Scientific Reports, 4, 7089. https://doi.org/10.1038/srep07089
Cohen Kadosh, R., Henik, A., Catena, A., Walsh, V., & Fuentes, L. J. (2009). Induced cross-modal synaesthetic experience without abnormal neuronal connections. Psychological Science, 20(2), 258–65. https://doi.org/10.1111/j.1467-9280.2009.02286.x
Colizoli, O., Murre, J. M. J., & Rouw, R. (2012). Pseudo-Synesthesia through reading books with colored letters. PLoS ONE, 7(6). https://doi.org/10.1371/journal.pone.0039799
Colizoli, O., Murre, J. M. J., Scholte, H. S., van Es, D. M., Knapen, T., & Rouw, R. (2016). Visual cortex activity predicts subjective experience after reading books with colored letters. Neuropsychologia, 88(July), 15–27. https://doi.org/10.1016/j.neuropsychologia.2015.07.006
Grossenbacher, P. G., & Lovelace, C. T. (2001). Mechanisms of synesthesia: cognitive and physiological constraints. Trends in Cognitive Sciences, 5(1), 36–41. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/11164734
Luke, D. P., & Terhune, D. B. (2013). The induction of synaesthesia with chemical agents: a systematic review. Frontiers in Psychology, 4(October), 1–12. https://doi.org/10.3389/fpsyg.2013.00753
Meier, B., & Rothen, N. (2009). Training grapheme-colour associations produces a synaesthetic Stroop effect, but not a conditioned synaesthetic response. Neuropsychologia, 47(4), 1208–1211. https://doi.org/10.1016/j.neuropsychologia.2009.01.009
Neufeld, J., Roy, M., Zapf, A., Sinke, C., Emrich, H. M., Prox-Vagedes, V., … Zedler, M. (2013). Is synesthesia more common in patients with Asperger syndrome? Frontiers in Human Neuroscience, 7(December), 847. https://doi.org/10.3389/fnhum.2013.00847
Novich, S., Cheng, S., & Eagleman, D. M. (2011). Is synaesthesia one condition or many? A large-scale analysis reveals subgroups. Journal of Neuropsychology, 5(2), 353–71. https://doi.org/10.1111/j.1748-6653.2011.02015.x
Rich, a N., Bradshaw, J. L., & Mattingley, J. B. (2005). A systematic, large-scale study of synaesthesia: implications for the role of early experience in lexical-colour associations. Cognition, 98(1), 53–84. https://doi.org/10.1016/j.cognition.2004.11.003
Rothen, N., Jünemann, K., Mealor, A. D., Burckhardt, V., & Ward, J. (2015). The sensitivity and specificity of a diagnostic test of sequence-space synesthesia. Behavior Research Methods. https://doi.org/10.3758/s13428-015-0656-2
Rothen, N., & Meier, B. (2010). Higher prevalence of synaesthesia in art students. Perception, 39(5), 718–720. https://doi.org/10.1068/p6680
Rothen, N., Meier, B., & Ward, J. (2012). Enhanced memory ability: Insights from synaesthesia. Neuroscience and Biobehavioral Reviews, 36(8), 1952–63. https://doi.org/10.1016/j.neubiorev.2012.05.004
Sagiv, N., Heer, J., & Robertson, L. (2006). Does binding of synesthetic color to the evoking grapheme require attention? Cortex; a Journal Devoted to the Study of the Nervous System and Behavior, 42(2), 232–42.
Simner, J., Mulvenna, C., Sagiv, N., Tsakanikos, E., Witherby, S. A., Fraser, C., … Ward, J. (2006). Synaesthesia: The prevalence of atypical cross-modal experiences. Perception, 35(8), 1024–1033. https://doi.org/10.1068/p5469
Simner, J., Ward, J., Lanz, M., Jansari, A., Noonan, K., Glover, L., & Oakley, D. a. (2005). Non-random associations of graphemes to colours in synaesthetic and non-synaesthetic populations. Cognitive Neuropsychology, 22(8), 1069–85. https://doi.org/10.1080/02643290500200122
Terhune, D. B., Luke, D., Terhune, D. B., Luke, D. P., & Kadosh, R. C. (2017). The Induction of Synaesthesia in Non- The Induction of Synaesthesia in Non-Synaesthetes, (November).
Tomson, S. N., Avidan, N., Lee, K., Sarma, A. K., Tushe, R., Milewicz, D. M., … Eagleman, D. M. (2011). The genetics of colored sequence synesthesia: suggestive evidence of linkage to 16q and genetic heterogeneity for the condition. Behavioural Brain Research, 223(1), 48–52. https://doi.org/10.1016/j.bbr.2011.03.071
Ward, J., Thompson-Lake, D., Ely, R., & Kaminski, F. (2008). Synaesthesia, creativity and art: what is the link? British Journal of Psychology (London, England : 1953), 99(Pt 1), 127–41. https://doi.org/10.1348/000712607X204164
Ward, J., & Wright, T. (2014). Sensory substitution as an artificially acquired synaesthesia. Neuroscience and Biobehavioral Reviews, 41, 26–35. https://doi.org/10.1016/j.neubiorev.2012.07.007
Witthoft, N., Winawer, J., & Eagleman, D. M. (2015). Prevalence of learned grapheme-color pairings in a large online sample of synesthetes. PLoS ONE, 10(3), 1–10. https://doi.org/10.1371/journal.pone.0118996
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