Watch Laura as she gets out of bed and brushes her teeth. It seems like a typical Saturday at first, but observe the morning through Laura’s senses. As she tastes the minty toothpaste, she sees long ribbons of faded purple that extend into the horizon. The pain in her stubbed toe produces sharp spikes of dark gray on a lemon yellow background. She smells the coffee brewing, which evokes soft red spheres that cascade upwards like bubbles. The newspaper is not black and white for her. Every letter and word has a specific hue, transforming the text into a kaleidoscope of fantastical colors.
While this may seem bizarre to the average person, for Laura (and for one in every 2,000 people) it is perfectly natural. This is the condition of synesthesia, which comes from Greek words meaning “union of sensation.” A person with synesthesia, or a synesthete, experiences a combination of two or more senses in response to one perceived stimuli. The percept, or the sensory experience that synesthesia presents, lingers for a short amount of time and then fades away. Synesthetes can be anyone, but the rate is much, much higher among women than men. Many people experience perceptions similar to synesthesia as a result of drug use, epilepsy, and brain lesions.
Unlike drug-induced hallucinations, real synesthesia cannot be repressed or summoned at will. When a stimulus is perceived, the resulting sensory response is automatic and out of the synesthete’s control. The percepts that result from synesthesia are usually consistent throughout the person’s life, and easily remembered. One test is to have the person record her synesthetic percepts, then retest her without warning. A true synesthete will have exactly the same descriptions of her percepts; when retested two years later, she will outperform non-synesthetes who are retested after only two weeks.
Synesthesia is not imagined; it is seen outside the body, though usually close to it. However, the percepts are always distinct from what the synesthete is actually seeing; they’re somewhere between the mind’s eye and the visual field. Does a synesthete actually see color when she looks at numbers or letters? When shown a picture with tiny black 5’s and 2’s randomly mixed together, a normal person would have to painstakingly search and pick out each two. A synesthete could take one look and instantly spot all the 2’s by their color alone.
Most synesthetes have had the condition for as long as they can remember. They automatically believe that everyone else experiences synesthesia because it is all they have ever known. After a synesthete discovers that her family and friends don’t share her perceptions, she concludes that she is the only synesthete in the world. As an adult she will rarely share her synesthesia with anyone; when she does, she will probably be embarrassed and apologetic about it. Richard Cytowic, an expert on synesthesia, once attended a dinner party and overheard the host, Michael, comment that there were “too many points on the chicken” (p.3). When confronted, Michael explained that he perceived flavors as physical shapes, mostly on his face and hands. Flustered and ashamed, he told Cytowic, “Nobody’s ever heard of this. They think I’m on drugs or that I’m making it up. That’s why I never intentionally tell people about my shapes. Only when it slips out.” Still, ask any synesthete to live without their synesthesia and they will vehemently refuse. It is as natural as breathing to them, and they cannot imagine perceiving their world in any other way. This is one of the fundamental characteristics of synesthetes: they have absolute confidence that what they see is real and valid, perhaps even more true than “normal” vision.
The cause of synesthesia is still under debate. The most widely accepted theory at this time is that synesthesia is caused by the cross-activation of sensory maps. This is supported by the fact that in the brain, the visual area (the fusiform gyrus) borders the color area; this explains the much higher occurrence of colored letters and words than any other kind of synesthesia. Synesthetic perceptions are still subject to top-down processing, however. Precepts can change depending on where one’s attention is focused and how one’s brain categorizes the stimulus. With improving technology and increasing attention to this fascinating condition, more and more headway is made every day into discovering the “how” and “why” of synesthesia.
