Hearing and tasting colours: the multisensory mystery of synaesthesia

For around 4% of the population, the concept of colour is much more than a stimulation of photoreceptor cells: those who experience synaesthesia are able to hear colours, or associate colours with letters, numbers and even music. The word synaesthesia comes from the Greek ‘syn’ (meaning union) and ‘aesthesis’ (meaning sensation). Therefore, this rare condition allows people to experience more than one sense at the same time.1
This perplexing phenomenon extends to not only the sense of sight, but various other senses e.g. touch, taste, hearing and smell being experienced at the same time. Grapheme-colour synaesthesia is when people perceive letters and numbers as having a certain colour and even a personality. For example, the letter A might be associated with the colour yellow.2 Another type of colour synaesthesia is chromesthesia, which is when someone can experience colours as a result of sound. The singer, Lorde, has chromesthesia and it plays a large part in her creativity as a musician: her song, ‘Tennis Court’, developed from her perception of the melody as a ‘tan’ colour changing into a ‘green’ colour. 3
Synaesthesia is a puzzling condition and because the brain is so hard to study, accurate data is very difficult to gather. However, there are a few main theories as to why synaesthesia occurs. According to the psychologist Sir Simon Baron-Cohen from the University of Cambridge, the condition is caused by ‘an overabundance of neural connections’4 causing enhanced communication between areas of the brain responsible for different senses, so a person with synaesthesia would experience more than one sense at a time. Another theory is that of Daphne Maurer, PhD, who proposed the notion that everyone could be born with the brain structure to facilitate synaesthesia, however these ‘neural connections’ become lost to most of the population during development.4
Furthermore, it is thought that synaesthesia may be a genetic condition. There are two general types of synaesthesia: perceptual and conceptual. Which type is experienced could depend on the location of gene expression. Perceptual synaesthesia occurs when the gene is expressed in the fusiform gyrus (the area of the brain responsible for object and facial recognition) – the person will actively see the colour, taste or smell. Conceptual synaesthesia would occur when the gene is expressed in the angular gyrus (the area of the brain related to memory retrieval among other things) – the person will associate or connect the colour, taste or smell.5
Although it is certainly true that many congenital synaesthetes experience their condition from birth, in some incidences, synaesthesia can be induced. For example, someone who suffers neural damage may permanently experience synaesthesia, whereas someone who takes drugs (particularly hallucinogens) may do so temporarily.6 Additionally, the consistency in responses which characterises authentic synaesthesia can also be replicated through associative conditioning, where the aim is to create a mental link between a certain stimulus and a synaesthetic response. 7
In conclusion, synaesthetes experience the world in a remarkably unique way, and it would certainly be incorrect to categorise this condition as a disorder. As medical technology improves and we begin to dig deeper and uncover the complex secrets of neuroscience, I personally hope that more research goes into discovering more about this condition.

  1. Cytowic, Richard E. 2013. “What color is Tuesday? Exploring synesthesia.” YouTube. https://www.youtube.com/watch?v=rkRbebvoYqI.
  2. synesthesia.com. 2016. “Grapheme-colour synesthesia.” synesthesia.com. https://synesthesia.com/blog/grapheme-color-synesthesia/.
  3. Fasanella, Kaleigh. 2017. “Lorde Opens Up About How Synesthesia Helps Her Make Music.” Teen Vogue. https://www.teenvogue.com/story/lorde-opens-up-about-synesthesia-hit-music.
  4. Carpenter, Siri. 2001. “Everyday fantasia: The world of synesthesia.” American Pyschological Association. https://www.apa.org/monitor/mar01/synesthesia.
  5. Zabellna, Darya L. 2011. “Are you a Synesthete?” Psychology Today. https://www.psychologytoday.com/gb/blog/finding-butterfly/201104/are-you-synesthete.
  6. Technology Networks. 2015. “Trippy research: Chemically-induced synesthesia.” Technology Networks. https://www.technologynetworks.com/neuroscience/articles/trippy-research-chemically-induced-synesthesia-284935.
  7. Walsh, Roger. 2003. “Can Synaesthesia Be Cultivated?” drrogerwalsh.com. http://drrogerwalsh.com/wp-content/uploads/2011/06/Can-Synaethesia-Be-Cultivated_Walsh.pdf.

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