The Tell-Tale Brain

“Why, different hens of course,” replied the farmer.

“Well, do me a favor,” said the president. “Tell the First Lady what you just told me.”

This story may be apocryphal, but it does raise a fascinating question. Would a patient with Capgras syndrome never get bored with his wife? Would she remain perpetually novel and attractive? If the syndrome could somehow be evoked temporarily with transcranial magnetic stimulation…one could make a fortune.

CHAPTER 3

  Loud Colors and Hot Babes: Synesthesia

“My life is spent in one long effort to escape from the commonplaces of existence. These little problems help me to do so.”

—SHERLOCK HOLMES

WHENEVER FRANCESCA CLOSES HER EYES AND TOUCHES A PARTICULAR texture, she experiences a vivid emotion: Denim, extreme sadness. Silk, peace and calm. Orange peel, shock. Wax, embarrassment. She sometimes feels subtle nuances of emotions. Grade 60 sandpaper produces guilt, and grade 120 evokes “the feeling of telling a white lie.”

Mirabelle, on the other hand, experiences colors every time she sees numbers, even though they are typed in black ink. When recalling a phone number she conjures up a spectrum of the colors corresponding to the numbers in her mind’s eye and proceeds to read off the numbers one by one, deducing them from the colors. This makes it easy to memorize phone numbers.

When Esmeralda hears a C-sharp played on the piano, she sees blue. Other notes evoke other distinct colors— so much so that different piano keys are actually color coded for her, making it easier to remember and play musical scales.

These women are not crazy, nor are they suffering from a neurological disorder. They and millions of otherwise normal people have synesthesia, a surreal blending of sensation, perception, and emotion. Synesthetes (as such people are called) experience the ordinary world in extraordinary ways, seeming to inhabit a strange no-man’s-land between reality and fantasy. They taste colors, see sounds, hear shapes, or touch emotions in myriad combinations.

When my lab colleagues and I first came across synesthesia in 1997, we didn’t know what to make of it. But in the years since, it has proven to be an unexpected key for unlocking the mysteries of what makes us distinctly human. It turns out this little quirky phenomenon not only sheds light on normal sensory processing, but it takes us on a meandering path to confront some of the most intriguing aspects of our minds—such as abstract thinking and metaphor. It may illuminate attributes of human brain architecture and genetics that might underlie important aspects of creativity and imagination.

When I embarked on this journey nearly twelve years ago, I had four goals in mind. First, to show that synesthesia is real: These people aren’t just making it up. Second, to propose a theory of exactly what is going on in their brains that sets them apart from nonsynesthetes. Third, to explore the genetics of the condition. And fourth, and most important, to explore the possibility that, far from being a mere curiosity, synesthesia may give us valuable clues to understanding some of the most mysterious aspects of the human mind—abilities such as language, creativity, and abstract thought that come to us so effortlessly that we take them for granted. Finally, as an additional bonus, synesthesia may also shed light on age-old philosophical questions of qualia—the ineffable raw qualities of experience—and consciousness.

Overall I am happy with the way our research has proceeded since then. We have come up with partial answers to all four questions. More important, we have galvanized an unprecedented interest in this phenomenon; there is now virtually a synesthesia industry, with over a dozen books published on the topic.

WE DON’T KNOW when synesthesia was first recognized as a human trait, but there are hints that Isaac Newton could have experienced it. Aware that the pitch of a sound depends on its wavelength, Newton invented a toy—a musical keyboard—that flashed up different colors on a screen for different notes. Thus every song was accompanied by a kaleidoscopic display of colors. One wonders if sound-color synesthesia inspired his invention. Could a mixing of senses in his brain have provided the original impetus for his wavelength theory of color? (Newton proved that white light is composed of a mixture of colors which can be separated by a prism, with each color corresponding to a particular wavelength of light.)

Francis Galton, a cousin of Charles Darwin and one of the most colorful and eccentric scientists of the Victorian era, conducted the first systematic study of synesthesia in the 1890s. Galton made many valuable contributions to psychology, especially the measurement of intelligence. Unfortunately, he was also an extreme racist; he helped usher in the pseudoscience of eugenics, whose goal was to “improve” mankind by selective breeding of the kind practiced with domesticated livestock. Galton was convinced that the poor were poor because of inferior genes, and that they must be forbidden from breeding too much, lest they overwhelm and contaminate the gene pool of the landed gentry and rich folk like him. It isn’t clear why an otherwise intelligent man should hold such views, but my hunch is that he had an unconscious need to attribute his own fame and success to innate genius rather than acknowledging the role of opportunity and circumstance. (Ironically, he himself was childless.)

Galton’s ideas about eugenics seem almost comical in hindsight, yet there is no denying his genius. In 1892 Galton published a short article on synesthesia in the journal Nature. This was one of his lesser-known papers, but about a century later it piqued my interest. Although Galton wasn’t the first to notice the phenomenon, he was the first to document it systematically and encourage people to explore it further. His paper focused on the two most common types of synesthesia: the kind in which sounds evoke colors (auditory-visual synesthesia) and the kind in which printed numbers always seem tinged with inherent color (grapheme-color synesthesia). He pointed out that even though a specific number always produces the same color for any given synesthete, the number-color associations are different for different synesthetes. In other words, it’s not as though all synesthetes see a 5 as red or a 6 as green. To Mary, 5 always looks blue, 6 is magenta, and 7 is chartreuse. To Susan, 5 is vermillion, 6 is light green, and 4 is yellow.

How to explain these people’s experiences? Are they crazy? Do they simply have vivid associations from childhood memories? Are they just speaking poetically? When scientists encounter anomalous oddities such as synesthetes, their initial reaction is usually to brush them under the carpet and ignore them. This attitude—which many of my colleagues are very vulnerable to—is not as silly as it seems. Because a majority of anomalies—spoon bending, alien abduction, Elvis sightings—turn out to be false alarms, it’s not a bad idea for a scientist to play it safe and ignore them. Whole careers, even lifetimes, have been wasted on the pursuit of oddities, such as polywater (a hypothetical form of water based on crackpot science), telepathy, or cold fusion. So I wasn’t surprised that even though we had known about synesthesia for over a century, it has generally been sidelined as a curiosity because it didn’t make “sense.”