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Artists such as Pharrell Williams and Kanye West have openly discussed their synesthesia, with West describing it as a tool to create "sonic paintings" and "visualize sound."
How prevalent is synesthesia? What defines it, and what causes it? As a relatively new field of research, scientists continue to explore these questions to uncover more about this fascinating phenomenon.
DEFINING SYNESTHESIA: WHAT DOES IT ENTAIL?
Synesthesia is a neurological phenomenon where the senses intertwine in unusual ways. For instance, sounds might not only be heard but also seen, or flavors might be tasted and simultaneously visualized. As the late Dr. Oliver Sacks described to American Public Media in 2009, it’s as though there’s an 'excessive or abnormal connection between sensory areas that are typically separate.'
Each synesthete’s experience is unique, but they typically fall into two categories: projective or associative. Projective synesthesia involves tangible sensory experiences, like seeing a red blob in the room or feeling a sudden warmth on the skin. Associative synesthesia, on the other hand, evokes related concepts, emotions, or memories.
The potential combinations of senses and stimuli are vast, but the most prevalent forms of synesthesia include grapheme-color synesthesia, where numbers or letters trigger specific colors; chromesthesia, where sounds or music evoke colors; spatial sequence synesthesia, where numbers are perceived in spatial arrangements; and number form synesthesia, which creates mental maps of numerical sequences.
HOW AND WHY DOES SYNESTHESIA OCCUR?
Research [PDF] indicates that synesthesia is a hereditary trait that can skip generations, with synesthetic experiences being 'automatic.' Studies consistently suggest a distinction between synesthetes and nonsynesthetes, though the exact nature of this difference remains unclear. According to the 2015 review 'Developing synesthesia: a primer,' the potential causes of synesthesia are increasingly diverse and complex.
For instance, the immune hypothesis, proposed in 2013, posits that 'the interplay between the central nervous system and the immune system during early development could be crucial in the emergence of synesthesia.' Conversely, the neonatal hypothesis suggests that synesthetic connections, such as those between shapes and colors, may form in early childhood (e.g., while learning the alphabet with colored blocks) and persist, potentially disrupting the learning of new shape-color associations later in life.
Sean Day, president of the American Synesthesia Association (ASA), believes these heightened connections may stem from subtle yet significant anatomical differences in synesthetes' brains. Recent studies suggest that myelin, the fatty insulation around nerves, is more developed in synesthetes, particularly along pathways connecting sensory regions.
As Day explained to NPR, 'The unique myelination alters how different brain regions interact.' Since myelin facilitates rapid neural signal transmission, the enhanced pathways in synesthetes' brains likely foster intriguing collaborations between two or more senses.
WHO EXPERIENCES SYNESTHESIA?
Estimates of synesthesia's prevalence vary, but current studies suggest it affects roughly four percent of the population. Due to limited research and the absence of a universal diagnostic tool, the exact number of individuals experiencing these sensory crossovers—or the frequency of each synesthetic type—remains uncertain.
BBC News highlights that the list of synesthetes features the abstract painter and art theorist Wassily Kandinsky, who expressed “his experience of visualizing music through color, line, and form.” Renowned artists like Vincent Van Gogh and David Hockney also delved into the possibilities of representing their unique perceptions in their artwork, embracing vibrant colors much like Kandinsky. Additionally, many celebrated musicians, including Tori Amos, Jean Sibelius, Eddie Van Halen, Itzhak Perlman, and Leonard Bernstein, are known to experience synesthesia.
WHAT DOES SYNESTHESIA FEEL LIKE?
From perceiving a splash of mauve in the air during a Metallica performance to instinctively associating the number 12 with the color green, each synesthete’s sensory connection is unique. Pitchfork describes how Duke Ellington visualized “a D note as dark blue burlap and a G as light blue satin,” while Pharrell Williams experienced baby blue and burgundy tones when listening to Earth, Wind & Fire for the first time.
Dr. Carol Crane, a synesthesia researcher, shared with Monitor on Psychology that guitar music feels like it “[brushes] gently against her ankles,” while trumpets “announce themselves on the back of her neck.” Day, the ASA president and a linguistics professor in Taiwan, added that the taste of steak evokes “a deep blue,” and steamed gingered squid conjures “a large, bright orange foam, positioned about four feet in front of me.”
Simon Baron-Cohen, a synesthesia researcher at the University of Cambridge (and Borat’s real-life cousin), notes that most synesthetes are satisfied with their unique way of experiencing the world. “When asked if they’d want to lose their synesthesia, they almost always decline,” Baron-Cohen told Monitor on Psychology. “To them, it feels like the norm. Losing it would make them feel as though they’ve lost one of their senses.”
Recent findings from a preliminary study by the British Psychological Association suggest that the advantages of synesthesia may now be quantifiable. The research aimed to identify potential links between synesthesia and specific personality traits or cognitive abilities. It revealed that synesthetes, compared to non-synesthetic participants, demonstrated higher levels of absorption, verbal comprehension, visual convergent thinking, openness to experience, originality in verbal divergent thinking, and the use of mental imagery, ranked by the magnitude of the observed effects.
For those with synesthesia, this is a visual symphony.
