Turquoise Melodies and Quadrilaterals for Breakfast: The Life of a Synesthete
Synesthesia is a neurological condition which joins sensory perceptions. The most common variety links numbers and letters (and often words like the days of the week) with colors. However people with synethesia can experience a slew of unique sensations ranging from tasting shapes to seeing sounds.
In neurologist Richard Cytowic’s book, ‘The Man Who Tasted Shapes’, a synesthetic dinner host describes his experiences: “When I taste something with an intense flavor, the feeling sweeps down my arms into my fingertips. I feel its weight, texture, [temperature], everything. I feel it like I’m actually grasping something.” For him, the taste and aroma of a meal elicit a strong tactile sensation.
Before extensive studies had been conducted on this condition, accounts of synathetic experiences were viewed as out-of-the-ordinary imaginative metaphors and not taken seriously. But in recent years Cytowic has heavily researched synesthesia and has determined its diagnostic criteria, the most significant being that these mixed perceptions are involuntary and automatic.
Tests such as the one below have shown to prove the case. When the image to the left is presented to an individual without the condition, he/she considers it slightly difficult to distinguish the 5’s from the 2’s. Synesthetes (in particular those with a number-color association) can almost seamlessly make the distinction between the numbers due to the specific colors which they may have come to innately pair with them (as the image on the right shows, the synesthete associates 5 with green and 2 with red).
There have been multiple theories for synesthesia. A popular one suggested that it was caused by neural “cross-wiring” between interpretive areas. For example, a color processing region in the brain’s visual cortex called V4 lies adjacent to an area responsible for identifying letters and numbers, and a mixed perception of color and letters/numbers could be attributed to cross activation between these areas.
However, Cytowic and his collegue David Eagleman propose a better hypothesis: that the neurological condition is really caused by a slight difference in the balance of excitation and inhibition. When chemical inhibitors, which repress other types of processing during a specific sense experience, are blocked, it is possible to sense blue from a red object without any contradiction. This theory was put forward because we know that non-synesthetes can aquire synethesic “symptoms” under the influence of psychoactive drugs like LSD. So, we’re all capable of producing unnatural sensory combinations, but a lucky few of us can do it everyday.
The Man Who Tasted Shapes by Richard E. Cytowic