Senses Interconnection — Seeing Taste and Hearing Color

Synesthesia is a condition described as the interconnection between sensory modalities. Meaning that one of the senses, for example, visual, auditory, or tactile, will involuntarily invoke another sensation — your senses are confused. This could be the case in hearing or reading colors, tasting words, seeing music, or similar bizarre-sounding experiences.

Synesthesia should not be confused with common association. It is not the case that synesthetes — people who suffer from synesthesia — associate the color blue with cold, snow, or ice, or the taste of a strawberry reminds us of summer and the like. Synesthesia is an involuntary directional connection between the senses. Thus, it is not learned by experience, or retrieved from our memories, rather, it is more like an unconscious reflex.

The term synesthesia is derived from two Greek words, “synth”, meaning together, and “ethesia”, meaning perception.

How common is synesthesia?

There are many types of synesthesia, given that any of the senses can be interconnected with any other sensation. Studies show that there are at least 60 different forms of synesthesia recorded. However, researchers stress there could be more.

Scientists estimate that the prevalence of synesthetes is between 2% and 5% in the general population. The two most common types of synesthesia are auditory-color and number-color synesthesia. In these cases, an auditory tone or a colorless number will invoke vivid color perceptions.

It is also possible for an individual to have more than one synesthesia. For example, an individual may have sound-to-color and number-to-color synesthesia. In the case of multiple synesthesias, it does not necessarily mean that different sensory modalities would be connected to another sensory modality, as in the example above. To illustrate, an individual could have sound to color and taste to number synesthesia.

What causes synesthesia?

Researchers have struggled to find a cause for synesthesia. Recorded cases have cited synesthesia incidents evoked by hallucinogenic drugs or after sensory deprivation. However, these episodes tended to be temporary experiences. Therefore, some argued that they are not synesthesia and should not be labeled as such. In addition, in some individuals, synesthesia occurred as a result of brain damage; however, these were extremely rare cases that lacked insight.

The major consensus in research and academic communities is that synesthesia is a genetic condition, however, scientists have yet to pinpoint the exact gene variants. Given that there are more than 60 different types of synesthesia, i.e., different coupling between the senses, with an assumption that this number is even higher, it is suggested that each type of synesthesia is caused by a different set of genes and their variants.

What we know so far is that the genetic component of synesthesia is quite strong — it’s inherited. Studies on this condition indicate that approximately 40% of synesthetes report at least one other family member with synesthesia. In addition, family studies indicate that the heritability of synesthesia is highest between parent-to-offspring.

Medical professionals have only diagnosed a single case in identical twins where only one child inherited the condition. However, it is important to note that the type of synesthesia can vary within the family, meaning that a parent could have color-to-sound, but a child could have number-to-color synesthesia.

Finally, a working theory on the development of synesthesia proposes that it is a result of decreased neural pruning — a process where the brain gets rid of what it doesn’t need anymore — which happens between infancy and puberty. This synaptic pruning removes excess neural connections that are connected in a fetus but are removed during development. This results in a large number of remaining neural connections between the sensory areas of the brain.

Living with synesthesia

Overall, living with synesthesia has been indicated as a positive experience. This condition does not affect the well-being of an individual, and they tend to function well in their work, relationships, or education. Synesthesia is a life-long condition that remains stable over time. Given that there are no negative implications of this condition, no treatment has been developed for synesthetes.

There seems to be a correlation between synesthesia and creativeness. Research data show that synesthesia is common among artists. Individuals who have been interviewed with this condition indicate that it had a positive impact on their creative abilities.

Individuals with synesthesia tend to be successful in any field but are more likely to be involved in creative activities than the general population. Many studies show a correlation between synesthesia and creativeness. However, though the data is compelling, it is not conclusive.

There is little data supporting whether synesthesia benefits other domains of cognitive functioning, such as memory. Some studies suggest a slight advantage in individuals with synesthesia. However, these are single reports, which can’t be taken as an absolute truth.

Key takeaways

Synesthesia is a condition where one sensory perception will involuntarily invoke another sensory perception.

Synesthesia is a highly heritable condition.

Synesthesia seems to be related to creativeness.

Living with synesthesia overall is considered a positive experience.

Resources:

Brang, D., & Ramachandran, V. S. (2011). Survival of the synesthesia gene: Why do people hear colors and taste words?. PLoS biology, 9(11), e1001205.

Johnson, D., Allison, C., & Baron-Cohen, S. (2013). The prevalence of synesthesia. Oxford handbook of synesthesia, 1.

Spector, F., & Maurer, D. (2009). Synesthesia: a new approach to understanding the development of perception. Developmental psychology, 45(1), 175.

Ward, J. (2013). Synesthesia. Annual review of psychology, 64, 49-75.

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