RICHARD E. CYTOWIC MD
Neurologist

Well, what is synaesthesia? Everybody knows the word ‘anesthesia’ which means no sensation. Synaesthesia means joined sensation, where two or more of the senses are hooked together, so that my voice for example is not only something that they hear but also something that they see or taste or touch.

The most common form of synaesthesia is colored letters and numbers. That is, joining color to integers. That accounts for about two-thirds of cases. The next big group would be sight and sound synaesthesia, or what is called colored hearing. In this, voices, music, environmental sounds will make people see colored photisms—these are shapes that arise, they change and metamorphose a little bit and fade away. Think of it as a little bit like fireworks. So they have a location and space they move around. And they enjoy it very much. There is almost a eureka sensation with this. They can’t imagine what listening to music is like for the rest of us. Of how do we remember people’s names or phone numbers if there is no color there to help us?

Synaesthesia isn’t something that you do, it is something that happens to you. There must be a stimulus that sets it off and the response in involuntary and automatic. The best methodology says that at least 1 in 2,000 people have some kind of synaesthetic experience. It is something that all of us have, but only reaches consciousness in a minority of people, and these people we call synaesthetes.

What’s the evidence for that? A number of lines converge there. One of them would be the neo-natal synaesthesia hypothesis. All of us who study this now agree that all neo-nates are born synaesthetic, and lose this ability as the brain matures over the first months of extra-uterine life. And normally excess and working projections between cortical sites that support different senses, different functions, are pruned. This is called physiological necrosis. And the failure – and we know this because in many species of mammals, in newborns you find present and working connections between vision and hearing… and they disappear fairly quickly. But the brain is changing itself enormously during the first 11 years of life, fairly robustly, and then much more slowly up until about age 20 to 25, when mylenation goes on. The brain is not a fixed thing, either genetically or environmentally– it responds to both things for quite a long time, physically.

So inheriting a genetic mutation, an X-link dominant trait, results in failure to prune these projections and their persistence, in adults, leads to synaesthesia. That’s the neo-natal synaesthesia hypothesis. The other is that, in The Man Who Tasted Shapes, I suggested that if we could quiet down—because I established a sort of limbic cortical polarity, saying that the expression of synaesthesia depended upon a relative quieting of the analytic neo-cortex and a relative enhancement of limbic dimensions.

Both Lawrence Marks and I agree that there is a continuum from synaesthesia to metaphor to language. He has written a lot about synaesthesia and metaphor, and a lot of people now believe that metaphor is an emergent property of mind. Heinz Werner said that we are all synaesthetic—he talked about synaesthesia in the ‘30s. But of course it has taken technology a long time to catch up with ideas. That continuum suggests that synaesthesia is not a high-level, abstract, linguistically-based metaphor—that’s a loud tie, she’s a sweet person, etc—but it is more at the perceptual end of the continuum. And so if it was not for synaesthesia, we probably would not have language.

Nobody can tell me what it is like to be a synaesthete. Even computer animations—and the fact that we have these form constants that what we see is very simple, conceptually, blobs and lines and movement and colors and stuff, you think it would be easy to describe. And yet, they can’t. This is an ineffable experience. The drawings that they make are only approximations, and even computer animations are said to be about 60 per cent representative of what it is really like. So there is an ineffable subjective experience aspect to it.

Synaesthesia comes at a cost. I have shown that synaesthetes – as a group - have trouble with mathematical skills, in right-left confusion, and navigation. So they get lost in grid cities. They come out of the elevator and they are all turned around. They have a terrible sense of direction, as a group. This makes sense because if you know something like cerebral organization is something of a zero-sum game. Excess talent, hyper-developed ability usually comes at the cost of something else.

Idiot savants illustrate the extreme principle of that; whereas for others, left-handedness is a sign of non-standard cerebral dominance. So that’s why you have a lot of left-handed males and architects, and athletes, because spatial ability and left-handedness seem to segregate together.

People often say, Boy doesn’t it drive you crazy having to see and hear all these extra bits and colors flying around/ And that’s like a blind person saying to you, You poor thing, everywhere you look you are always seeing. The answer is No, because this is what is normal for us. And so for synaesthetes, that is the texture of their reality—it is just different than ours.

Now have researchers in some 15 countries pursuing the puzzle of synaesthesia, and people doing their doctoral theses on it. Synaesthesia was always accepted as a real phenomenon in the 19th and 20th centuries. But the 20th century, especially behaviorism, did away with subjective experience as scientific data. So any kind of first-person experience had to be verified in the third person, often this means technological. So most scientists in the past few decades either rolled their eyes or shrugged their shoulders, said—I dunno, it’s a curiosity. But synaesthesia is not a mere curiosity; it illuminates a big swath of both mind and brain. And now that the hardest critics have gotten the proof that they demanded—and this proof consists of pictures, because we have this craze for functional imaging, as if that’s the only way to explore the mind, and brain, and consciousness. But now that you have this proof there is a force-choice. You either continue to insist that synaesthesia is not real, or you have to change some very cherished notions about how the mind and brain are organized.

HINDERK EMRICH
Psychiatrist
University of Hanover Medical School

Synaesthesia is for all of us extremely fascinating in so far as it is a mixture of senses, a coupling of senses, which normally are not experienced and it is so interesting since it sheds a lot of light on subjectivity of experience of persons and of the relations of all of us towards the problem of reality, of what is real in our life.

Synaesthesia is a phenomenon. The persons who have this phenomenon acquire it very early in childhood and it is an extraordinary programming of the senses. That means you experience something for example, a tone or a pattern or a touch or a taste or a smell, and you have a combined completely different sensations. For example, a color or a shape, a visual phenomenon, or in some rare cases also acoustic phenomenon. And this is acquired much more often in females than in males, in a relation of about 6 to 1. So the question of course occurs as whether it has to do with genomes and the x-chromosome, the y-chromosome or what is the reason? Brain research shows that hormones have a very strong influencing effect on modules. That means the modules within the brain are clicked on or taken out in their function. And estrogens have a very strong modulating effect on special functions of the brain that have to do with the internal censorship. That means the evaluation: is this true? Is this possible? Is this according to the rules of my life or the past, and this type of censorship is influenced by the estrogens. So it might be, there is an extraordinary coherence within the brain that means that the senses are coupled with each other might have to do with the function of estrogens.

They live in another world; they live in a super-real world. We live in a world in which we experience an addition of the five senses: we hear something, we see something, we taste it, we touch it. And from this we compose our world. But they live in a hyper world in which there are combinations of the senses that produce another reality for them. And this reality is not easily explainable for the others. So what comes really out is that there is an intermingling of senses. But the type of the intermingling senses is in every person completely different.

The synaesthetic world is full of astonishing phenomena. Of course also pain can be regulated more easily due to the coupling with colors. However I have to inform you that also normal persons who are not synaesthetes can code their pains in colors and these colors help them to cope with pain. Interestingly, the regulation of mood and affect and anger and other experiences of the emotional life are influenced also by the synaesthesian phenomena.

I would say the main point of view here is that synaesthetes have a stronger internal coherence and a tighter coupling with their feelings. The division is between mind and emotion, between mind and the concreteness of life, of the concreteness of touch, of the concreteness of feeling. This coupling is tighter in synaesthetes.

We have a very strong split between reality and internal feelings. They have more coherence with outer reality and inner reality and mind. So from a neuro-biological point of view one could say they are in a situation of hyper-binding. Binding says that we all, if we use our five senses, have to coordinate them. We produce contexts; we are producers of meaning, producers of contexts, and this production of a context is realized by so-called binding, the trans-modal integration. But they have a hyper binding. They integrate where normally no integration would occur. And for my neurobiological and also to some extend philosophical aspects of my work, it was very important to find out what is the reason: why do they do this hyper-binding, this hyper-integration?

We did a lot of neuro-biological research using at first functional EEG, brain function EEG, that means to look into different areas of the brain in this regard. And later, on functional imaging, using functional magnetic resonance tomography together with Professor Scheich in Magdeburg and both data point to the view that the coupling is induced by the so called limbic system. Limbic areas of the brain that are relevant in feelings, emotions, in valuation processes, perform this hyper coupling. That means, so to say, they have more activity in coherence-producing emotions, in coherence-producing feelings. They bind together different cognition and perception areas of the brain due to high activity of limbic functions of the brain.

You see, we have the evolution of biological systems. This is an evolution by Darwinian processes, by mutations, and so on. You have the evolution of brain of course. The brain has this encephalization that means, extreme growth of cortical structures. So possibly synaesthesia is a mode of cognitional evolution of mind. This is a speculation, we don't know it, but in some regards synaesthetes are higher, they have a more pronounced capacity of memorizing and they often have mathematical abilities. And they can visualize complex realities so it is possible that synaesthesia is one mode of the evolution of senses.

In synaesthesia, these integrating processes are fulfilled under different rules then in the other persons. And these different rules, which are driven by emotional processes, are so interesting for research. These rules are for example changed due to psychedelic drugs, LSD or psilocybin and other pro-psychotic compounds. But they are changed in an irregular way, that means if you are under LSD, you have synaesthetic experiences which are not rule-driven in a way...that always the number one produces a white color or a green color and so on, but from moment to moment the relation is different. However it is interesting to see that these mechanisms, which produce an integration or hyper-integration of senses are so vulnerable. They can be changed by drugs or they can be changed by situations, by emotional extreme states of the mind, and they can be changed with synaesthesia. This for the evolution of synaesthetes might be very, very important in the future.

I would completely agree with my friend Cytowic, that of course, the ability to produce synaesthetic experiences is a normal ability of the brain. But during the evolvement of the senses, during life, most of these capabilities are inhibited and can be disinhibited for example by psychedelic drugs like LSD, mescaline and so on, for a moment. And in some of the persons, these abilities in some channels, are disinhibited. This is what we call synaesthesia. These questions occur: Is it possible to learn synaesthesia? And as far as we know, we can only learn the metaphoric synaesthesia but not the real neurological synaesthesia. The metaphoric synaesthesia we to some extent have in practice, if we hear a concert and memorize pictures to it, and come from feelings to emotions, to situations of our life to imaginations and so on. And the more vivid all these experiences are, the more we are in so to say a metaphoric synaesthesia. And this helps us to come more and more in our own life. This is what Marcel Proust describes in his giant novel Search of the Past (Remeberance of Things Past) and what he describes with his experience of the madeleine, a cookie put in the tea and tasted, and the whole world of the past is coming out in imagination. This is a synaesthetic experience.

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