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Biology 202
2003 Second Web Paper
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Yellow Voices and Orange-Foam Squid: Questions about Synesthetic Reality

Danielle McManus

"What's first strikes me is the color of someone's voice. [V--] has a crumbly, yellow voice, like a flame with protruding fibers. Sometimes I get so interested in the voice, I can't understand what's being said." --From Synesthesia: A Union of the Senses by Robert E. Cytowic

What would you make of the preceding account? Would you think the speaker was...crazy?...on drugs?...making a play for attention? Would you be skeptical if the speaker told you it was her natural way of perceiving the world? In truth, it is an example of the way in which about one in every 25,000 people observes the world (1). The term (I hesitate to use "scientific term" for reasons I'll discuss further on) given to the condition-- synesthesia--derives from the Greek roots syn, meaning together, and aesthesis, to perceive, and conveys the principle features of the synesthete's perceptual state (2). In synesthetic perception, stimuli activate not just one sense, but several. An oral stimulus isn't a taste alone--it may also be a taste, a shape, a color, a movement (1). For example, a synesthete might explain that the taste of "squid produces a large glob of bright orange foam, about four feet away, directly in front of me" (3). Such joint perceptions are automatic and involuntary, just as is usual perceptual experience, and, unlike imaginary images or ideas, synesthetic perception is not only vividly real, but "often outside the body, instead of imagined in the mind's eye" (2).

Though accounts of synesthetic experience are receiving increased study and documentation, the many in the scientific community remain partially unconvinced, if not wholly dismissive. Lacking sufficient empirical, objective data to depict the synesthetic experience, synesthetes and researchers of the condition have had to combat doubt, disregard, and ridicule in defense of the condition's reality and validity. The question raised by synesthesia then becomes: Why does science discount first-person evidence to such an extent? If a condition has little to no "objective" or empirical "proof," does that mean it can't exist? If researchers can produce no computer read-out, no resonance imaging, no technologically-generated chart, should the scientific community turn up its nose?

The existence of synesthesia has been questioned and discussed for nearly 300 years, and it received the most enthusiastic investigation between 1869 and 1930 (12). At the time, many were fascinated by the unconscious mind and its possible links to synesthesia; yet interest began to wane when researchers were unable to reach any definite conclusions (4). A decade later, the advent of the behaviorist movement in the caused synesthesia to finally fall "off scientists' radar" entirely (3). The principles of behaviorism saw science as strictly an empirically-based field of study in which "anything meaningful" (5) had to be quantifiable or measurable by "objective" machines (4). Humans became scientific "subjects," individuality of experience was discounted, and "subjective experience, such as synesthesia, was deemed inappropriate for scientific study" (4). Studying and measuring behavior was the only sufficiently reliable means of gathering information about the human experience; consciousness and subjective experience were irrelevant, or worse, simply wrong (5). Influenced by the popular principles of behaviorism, modern scientists likely view reports of synesthesia as fine and well, but ultimately worthless as testable, provable scientific information. What use has "hard science" for whimsical metaphors about squid and orange foam?

These behaviorist-influenced attitudes make substantiation of synesthesia troublesome, for while the phenomenonlogy of synesthesia makes it apparent that the condition is a conscious experience, that experience has yet to be fully captured by technological data (4). Because of the subjective nature of perception, the only true understanding researchers have gleaned has typically come from first-person accounts--and therein lies the trouble. Validation of the synesthetic experience "is largely aesthetic" and fundamentally ineffable, "a phenomenon whose quality must be experienced first-hand" and is thus difficult for science to accept (4). Luciano da Costa, in an article critiquing synesthetic research, exemplifies such scientific skepticism:

"The very features considered for its [synesthesia's] diagnosis...rely heavily on phenomenological evidence, which, of course, is subjective. There is no doubt that as such, i.e., without cogent physiological or anatomical substantiation, synesthesia is destined to be treated with understandable scientific caution...[E]ven if thousands of documented cases were available, that would not be enough to qualify synesthesia as a real physical phenomenon" (6).

Da Costa's sentiments echo the contemporary scientific reluctance to accept synesthesia as scientifically valid, and further illustrate the field's "refusal to take any subjective reports seriously" (4). So then, if something can't be objectively verified, can we believe in its existence? I'd assert that yes, we can--and we should. When dealing with human experience, subjective data is an inevitable part of research, and offers "substantially more than nothing" to the effort of making sense of human behavior (5).

What are the reasons for this refusal to entertain subjective validity? In addition to holding to behaviorist principles, the scientific community may be leery of synesthesia for other reasons, including synesthesia's close relation to typical conceptions of metaphor and artistic expression. Creative language abounds with metaphors resembling synesthetic perceptions: sharp cheese, loud shirts, blue music. Hence the resulting "classic fallacy" of shelving synesthesia as "mere metaphor" (7)--that is, as the product of an active or overly fanciful imagination. This reaction is somewhat understandable, after all, because it is so difficult for synesthetes to portray exactly what synesthetic perception is like. Faced with such ambiguity, the best external observers can do is to approximate it to what they already know. The closest approximation most scientists are familiar with is metaphor and imaginative language, as it's regularly used in common discourse "to describe everything from food and wine to art and music" (1). Thus, it's understandable that scientists, without any other point of reference, would associate synesthetic expression with their own concept of metaphor. And if we conceive of our metaphoric descriptions with deliberate effort, wouldn't synesthetes be doing so as well? We don't experience cross-modal sensations, but we can create the idea of them--couldn't synesthetes just be convincing themselves that these creations are real? When one synesthete, told others of her music/shape synesthesia, they could only assume she was "making it up to get attention," "had an overactive imagination," "or was spoiled and wanted attention" (8). Without experiential reference, it's quite difficult just to conceive of such radically different perception, and how can you accept what you can hardly imagine? As one synethete explained, "Synesthesia isn't easy to fathom. People who don't have it have a hard time understanding...what it's like" (9). While understandable, to dismiss synesthesia on the basis that it seems impossible in one's personal conception of reality is to needlessly constrict the possibility of human experience and to hinder progress into new and challenging realms of inquiry.

Another reason is the belief that subjective reports make for problematic evidence. This is true in part: the subjectivity and individual experience implicated in perception not only makes synesthesia difficult to describe, but also difficult to compare to the experiences of other synesthetes (10). Because different synesthetes--even those with the same sensory pairings--usually don't report identical responses, that variability has been interpreted as proof that synesthesia isn't real (8). Moreover, because synesthetes aren't data-reading machines, they don't "have access to [information about] the neural and cognitive processes" underlying their synesthesia, which necessarily limits the scope of information they can provide (10). These problems should not however result in the outright rejection of subjective reports. As there are significant aspects of synesthesia that can't be described or captured using third-person methods, first-person accounts of synesthesia are essential to its understanding. The subjective contributions of synesthetes are therefore quite valuable as research tools, and could offer significant contributions to knowledge about the condition (10).

Finally, scientists may further doubt synesthesia's reality because of the oft-held idea that if a person's experience of the world diverges dramatically from the "norm" they must be mentally ill, or at least notably distressed. Yet synesthetes are neither. Very rarely, for those who experience stimuli across many senses, their synesthesia becomes so overpowering as to be uncomfortable or even unpleasant; but for the majority, synesthesia is quite normal, even pleasurable (8). Clinically, the mental state of the majority of synesthetes is balanced and the results of standard neurological exams prove normal (4). But "how is it that these perfectly healthy and otherwise neurologically normal people can experience color when there is not color there to be perceived" (9). One synesthete encountered such doubts when she mentioned her color/word perceptions to a teacher, and was promptly reported as a schizophrenic (8). The teacher (like many scientists) must have expected that no one could have such a radically altered idea of reality and be mentally stable. Abnormality is most often thought of as an obstacle, a deficit, a problem--synesthesia is not. As such, it challenges long-held conceptions of normal versus abnormal, and typical beliefs about reality and unreality. If a person experiences their world in a way radically different from us, aren't they necessarily crazy? Can someone be so different and yet be "normal?" This last question (to which I would argue yes), is potentially the most frightening of the questions raised by science's treatment of synesthesia. It implies that someone could perceive reality in a way wholly distinct from our own idea of reality and not be "crazy." This then begs the question, so what is crazy? If it's not always what we thought, could we be crazy? Small wonder scientists prefer to distance themselves from synesthesia and its "whiff of mysticism" (8).

Thus, while skepticism toward first-person accounts has merit, an uncompromising insistence on empirical data sacrifices a profound source of information to an excessive insistence on externality and objectivity. Rather than swing to one extreme (pure objectivism) or the other (pure subjectivism), perhaps there is a compromise in which each approach can be seen as mutually edifying. First-person reports can not only lay a basic framework for experimentation and the generation of new hypotheses, they can also be used to compare objective results to actual subjective experience. First-person data could also help to better explain experimental inconsistencies by providing insight into "individual differences between synesthetes" (10). Without this sort of real-world check of empirical data, the results would be substantially less valuable and applicable outside the laboratory. In the end, ignoring first-person accounts would not be "a victory for objective science," but a victory for "an intolerantly narrow vision of science" (5).

If something can't be imagined with our own personal experience, does that then mean it can't exist in another? Is our notion of reality the only truth? I don't have the ultimate answers to such sticky questions, but I do think that to dismiss synesthesia out of an unspoken fear of raising these queries and challenging the sense of complacency they offer would be both craven and detrimental. We shouldn't capitulate to fear or forego discovery in order to maintain a sense of stability. Synesthesia should be explored as far as possible, allowing first-person accounts to generate new theories and support what information researchers discover. In the end, conclusions about the reality of divergent human perception shouldn't rest exclusively with inflexible (and possibly unattainable) standards of objectivity. Scientists would be foolish to insist on it as they have in dealing with synesthesia; such disregard would deaden the nature of inquiry, of stretching beyond previous bounds and moving in new circles of thought and conception. We shouldn't allow the pursuit of knowledge to be so enslaved by technological, objective information that we doubt our own knowledge of the world around us. To do so would be to further distance human experience from the ability to know or posit truth.


1)Synesthesia, an interview with Richard Cytowic, on the ABC Radio National Transcripts site.

2)Synesthesia and the Synesthetic Experience, a site by the Massachusetts Institute of Technology.

3)Everyday Fantasia: The World of Synesthesia, a journal article by Siri Carpenter on the APA site.

4)5) Synesthesia and Method, a journal article by Kevin B. Korb, on the Psyche site.

6) Synesthesia - A Real Phenomenon? Or Real Phenomena?, a journal article by Luciano da Costa, on the Psyche site.

7)Hubbard, E.M and V.S. Ramachandran. "Psychophysical Investigations into the Neural Basis of Synesthesia. The Royal Society 268 (2001): 979 - 981.

8)Cytowic, Robert E. Synesthesia: A Union of the Senses. 2nd ed. Cambridge: Massachusetts Institute of Technology, 2002.

9)"Blue Cats and Chartreuse Kittens" by Patricia Lynne Duffy, a review of Duffy's book by Alison Motluk, on the site.

10) Towards a Synergetic Understanding of Synesthesia: Combining Current Experimental Findings with Synesthetes' Subjective Descriptions, a journal article by Daniel Smilek and Mike J. Dixon, on the Psyche site.

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