Studies to test these ideas with brain imaging. The experiment took four years, but we were finally able to show that, in grapheme-color synesthetes, the color area V4 lights up even when you present colorless numbers. This cross-activation could never happen in you or me. In recent experiments carried out in Holland, researchers Romke Rouw and Steven Scholte found that there were substantially more axons (“wires”) linking V4 and the grapheme area in lower synesthetes compared to the general population. And even more remarkably, in higher synesthetes, they found a greater number of fibers in the general vicinity of the angular gyrus. This all is precisely what we had proposed. The fit between prediction and subsequent confirmation rarely proceeds so smoothly in science.
The observations we had made so far broadly support the cross-activation theory and provide an elegant explanation of the different perceptions of “higher” and “lower” synesthetes.4 But there are many other tantalizing questions we can ask about the condition. What if a letter synesthete were bilingual and knew two languages with different alphabets, such as Russian and English? The English represent more or less the same phoneme (sound) but look completely dissimilar. Would they evoke the same or different colors? Is the grapheme alone critical, or is it the phoneme? Maybe in lower synesthetes it’s the visual appearance that drives it whereas in higher synesthetes it’s the sound. And what about uppercase versus lowercase letters? Or letters depicted in cursive writing? Do the colors of two adjacent graphemes run or flow into each other, or do they cancel each other out? To my knowledge none of these questions have been adequately answered yet—which means we have many exciting years of synesthesia research ahead of us. Fortunately, many new researchers have joined us in the enterprise including Jamie Ward, Julia Simner, and Jason Mattingley. There is now a whole thriving industry on the subject.
Let me tell you about one last patient. In Chapter 2 we noted that the fusiform gyrus represents not only shapes like letters of the alphabet but faces as well. Thus, shouldn’t we expect there to be cases in which a synesthete sees different
To add to the mystery, Robert also had Asperger syndrome, a high-functioning form of autism. This made it difficult for him to understand and “read” people’s emotions. He could do so through intellectual deduction from the context, but not with the intuitive ease most of us enjoy. Yet for Robert, every emotion also evoked a specific color. For example, anger was blue and pride was red. So his parents taught him very early in life to use his colors to develop a taxonomy of emotions to compensate for his deficit. Interestingly, when we showed him an arrogant face, he said it was “purple and therefore arrogant.” (It later dawned on all three of us that purple is a blend or red and blue, evoked by pride and aggression, and the latter two, if combined, would yield arrogance. Robert hadn’t made this connection before.) Could it be that Robert’s whole subjective color spectrum was being mapped in some systematic manner onto his “spectrum” of social emotions? If so, could we potentially use him as a subject to understand how emotions—and complex blends of them—are represented in the brain? For example, are pride and arrogance differentiated solely on the basis of the surrounding social context, or are they inherently distinct subjective qualities? Is a deep-seated insecurity also an ingredient of arrogance? Are the whole spectrum of subtle emotions based on various combinations, in different ratios, of a small number of basic emotions?
Recall from Chapter 2 that color vision in primates has an intrinsically rewarding aspect that most other components of visual experience do not elicit. As we saw, the evolutionary rationale for neurally linking color with emotion was probably initially to attract us to ripe fruits and/or tender new shoots and leaves, and later to attract males to swollen female rumps. I suspect that these effects arise through interactions between the insula and higher brain regions devoted to color. If the same connections are abnormally strengthened—and perhaps slightly scrambled—in Robert, this would explain why he saw many colors as strongly tinged with arbitrary emotional associations.
BY NOW I was intrigued by another question. What’s the connection—if any—between synesthesia and creativity? The only thing they seem to have in common is that both are equally mysterious. Is there truth to the folklore that synesthesia is more common in artists, poets, and novelists, and perhaps in creative people in general? Could synesthesia explain creativity? Wassily Kandinsky and Jackson Pollock were synesthetes, and so was Vladimir Nabokov. Perhaps the higher incidence of synesthesia in artists is rooted deep in the architecture of their brains.
Nabokov was very curious about his synesthesia and wrote about it in some of his books. For example:
…In the green group, there are alder-leaf f, the unripe apple of p, and pistachio t. Dull green, combined somehow with violet, is the best I can do for w. The yellows comprise various e’s and i’s, creamy d, bright-golden y, and u, whose alphabetical value I can express only by “brassy with an olive sheen.” In the brown group, there are the rich rubbery tone of soft g, paler j, and the drab shoelace of h. Finally, among the reds, b has the tone called burnt sienna by painters, m is a fold of pink flannel, and today I have at last perfectly matched v with “Rose Quartz” in Maerz and Paul’s
He also pointed out that both his parents were synesthetes and seemed intrigued that his father saw K as yellow, his mother saw it as red, and he saw it as orange—a blend of the two! It isn’t clear from his writings whether he regarded this blending as a coincidence (which it almost certainly is) or thought of it as a genuine hybridization of synesthesia.
Poets and musicians also seem to enjoy a higher incidence of synesthesia. On his website the psychologist Sean Day provides his translation of a passage from an 1895 German article that quotes the great musician Franz Liszt:
When Liszt first began as Kapellmeister in Weimar (1842), it astonished the orchestra that he said: “O please, gentlemen, a little bluer, if you please! This tone type requires it!” Or: “That is a deep violet, please, depend on it! Not so rose!” First the orchestra believed Liszt just joked;…later they got accustomed to the fact that the great musician seemed to see colors there, where there were only tones.
The French poet and synesthete Arthur Rimbaud wrote the poem, “Vowels,” which begins:
According to one recent survey, as many as a third of all poets, novelists, and artists claim to have had synesthetic experiences of one sort or another, though a more conservative estimate would be one in six. But is this simply because artists have vivid imaginations and are more apt to express themselves in metaphorical language?
