A lone man playing the electric guitar in a small living room. As he plays each individual chord, he begins to describe a scene similar to those of painting. A swirl of blue and green here, a swirl of yellow there, each individual chord contributing towards the tapestry of sound like an individual paint stroke in a grand painting. The phenomenon this man is going through is known to the scientific community as synesthesia.
Synesthesia is a neurological condition where the activation of one sensation often leads to an involuntary activation of another sensory sensation (Asher et.al, 2009). It is stated to affect around two to four percent of the world’s population, with many famous artists and musicians such as Wassily Kandinsky and Kanye West suggested to have this particular sensory phenomenon. So while this seems all well and good, but now you are probably asking what the deal is with the man that I mentioned in the beginning. Well, that man I was describing, in the beginning, happens to be my older cousin.
My cousin has a subclass of synesthesia classified as chromesthesia. Whenever he hears sounds such as music, he often sees flashes of color within his field of vision. He described the phenomenon of being like his own individual superpower, where he could see the world in his own unique way, and science seems to back up his own individual statement. A study conducted by Ward and company in 2017 found that when scientists look at the V4 part of the visual cortex (which is stated to be responsible for object recognition) shows that individuals with synesthesia showed greater visual performance compared to the general public (Ward et.al 2017). As a common individual, I always wondered what it would be like to see through my cousin’s eyes. After experiencing a multitude of sounds here in Paris, from the roar of the metro to a local philharmonic orchestra playing in Luxembourg garden, a new question began to pop into my head, why didn’t I have this condition? What was the underlying mechanism behind this phenomenon that allowed my cousin to develop this ability and I wasn’t?
While many methods such as specific types of drugs and hypnotic techniques have been noted to develop a false synesthetic like experience researchers call “artificial synesthesia”, the main underlying factor within the development of synesthesia seems to focus on a genetic influence (Deroy and Spence, 2013). A study conducted by Barnett and company in 2008 investigated the familial patterns of those who developed synesthesia. By conducting a systematic survey of 53 measured synaesthetic, it was found that nearly 42 percent of those who participated in this survey reported a first-degree relative (parent or sibling) who also was a synesthetic (Barnett et.al, 2008). What was interesting about this was that these first-degree synesthetic individuals did not necessarily share the exact same type of synesthesia, but may actually have different subsets. This research reflects the idea of synesthesia being a hereditary trait within immediate family members. This idea of the heritability of synesthesia is further supported when we look at the genetic markers underlying synaesthetic.
An investigation done by Asher and company in 2009 set out to understand the genetic influence that may underlie the development of synesthesia. Asher began his investigation by looking at a large group of 43 families of synesthetes recruited from the Cambridge Synaesthesia Research Group database (196 total participants, 121 who were affected, 68 unaffected and 7 unknown). After analyzing the genetic information of all individuals, it was suggested that four chromosomes (labeled 2q24, 5q33, 6p12, and 12p12) were said to hold evidence of genetic linkages (Asher et.al 2009). What this means is that these genes were identified to have been inherited together within families of those who have synesthesia.
While this information suggests a strong heritable cause for the development of synesthesia, the effect seems to be limited to those of immediate family members. Second-degree relationships like those between me and my cousin do not seem to reflect any correlation in terms of synesthetic heritability. While my cousin and I have been as close as brothers since as long as I could remember, it seems that our genetic code seems to keep me away from experiencing the sounds of the worlds in his eyes.
Although I may not be able to see the world through a near superhuman form of vision, it doesn’t change the amazement that this could mean towards the development of future generations. With synesthesia showing a strong genetic heritability, who knows, maybe this superhuman-like ability may be the visionary way to experience the world in the future.
Asher, J. E., Lamb, J. A., Brocklebank, D., Cazier, J. B., Maestrini, E., Addis, L.,Monaco, A. P. et.al (2009). A whole-genome scan and fine-mapping linkage study of auditory-visual synesthesia reveals evidence of linkage to chromosomes 2q24, 5q33, 6p12, and 12p12. American journal of human genetics, 84(2), 279–285. doi:10.1016/j.ajhg.2009.01.012
Barnett K, Finucane C, Asher J, Bargary G, Corvin A, Newell F, et al. (2008) Familial patterns and the origins of individual differences in synaesthesia. Cognition. 2008;106(2):871‐893. 10.1016/j.cognition.
Deroy, O., & Spence, C. (2013). Training, hypnosis, and drugs: artificial synaesthesia, or artificial paradises?. Frontiers in Psychology, 4, 660. doi:10.3389/fpsyg.2013.00660
Roe, A. W., Chelazzi, L., Connor, C. E., Conway, B. R., Fujita, I., Gallant, J. L., Vanduffel, W. et.al (2012). Toward a unified theory of visual area V4. Neuron, 74(1), 12–29. doi:10.1016/j.neuron.2012.03.011
Ward J, Rothen N, Chang A., et al. (2017) The structure of inter-individual differences in visual ability: evidence from the general population and synaesthesia. Vis Research;141: 293–302.
Image 2: Taken by me