Wired online carried a story recently on a talk by ‘neuroscientist extraordinaire’ V.S. Ramachandran, one of the folks responsible for a lot of creative thinking in the brain sciences. Brandom Keim writes on a recent talk Ramachandran gave at the World Science Festival in a story, Poetry Comes from Our Tree-Climbing Ancestors, Neuroscientist Says. While I typically find his stuff both fascinating and resonant, this particular piece left me unpersuaded.

Normally, I might take issue with the sloppy logic of the title (‘poetry’ coming from ‘tree-climbing ancestors’ being a dangerous conflation between non-proximate contributing factors and eventual effects — you could just as logically say that ‘poetry comes from spinning disk of post-stellar material in proto-solar system’…), but I’ve got bigger fish to fry: synesthesia.

Rmachandran’s work on synesthesia is excellent; for example, his piece with in Neuron on synesthesia is essential reading, and the piece he co-authored on the condition in Scholarpedia is my source for a fair bit of what I will write. The problem is that I don’t think that synesthesia is a good metaphor for, well, metaphor.

Although there may be some ways that metaphor is like synesthesia, when we add up the pros and cons, synesthesia as a metaphor for metaphor may not help us too much to understand the latter, and I seriously doubt that the two are linked in a more profound causal fashion (like a ‘gene’ for both synesthesia and metaphor). Similarly, attention-based failure to perceive something may be like blindness, but using one to try to explain the other is futile. In other words, not all metaphors are equally useful, and I’m concerned that the synesthesia metaphor for metaphor might do more harm than good.

Synesthesia is a neurological condition in which stimulation in one sensory channel causes involuntary sensations in another. For example, in grapheme, or color synesthesia, letters or numbers are perceived as having inherent colours; in ordinal linguistic personification, numbers, days of the week and months are perceived to have personalities; and in spatial-sequence, or number form synesthesia, numbers, days of the week or months elicit precise locations in space, or are perceived as occurring in topographical relationships (this is closely paraphrased from the Wikipedia article on synesthesia). Although the condition (it’s not really a ‘disorder’) was once thought very rare, but now some sources say that it may occur in around 4% of the population.

Synesthesia has been getting a lot of press of late for reasons that are not entirely clear to me. There’s a small (and probably not terribly lucrative) cottage industry on the boundary zone of social sciences and humanities where ‘synesthesia’ gets a lot of mileage. It appears to me to be part of a rethinking of psychological disorders into analogues for large-scale socio-cultural processes or global ethos, such as looking at Western society as schizophrenic or economics as autistic. While this has the agreeable side effect of pointing out that the gap between ‘disordered’ and ‘ordered’ development is perhaps not so great (and it can be great fun), it’s not clear that it always provides perfect analogues.

Part of the confusion produced by treating synesthesia as a metaphor for metaphor seems to stem from its use by Marshall McLuhan to discuss the effects of media (see James C. Morrison, Hypermedia and Synesthesia). While evocative, it’s not really a fair metaphor, in my opinion, and the farther we follow its implications, the worse it gets.

For example, if I say that many people are ‘paralyzed’ by fears about global climate change, that doesn’t necessarily mean that studying they neurological phenomenon of paralysis will necessarily get me any better understanding of the psychological reaction to fear of the planet warming. That is, a metaphor is a limited cognitive tool, an annalogic lens that highlights certain characteristics, but also with many other non-comparable traits; the metaphoric equation of synesthesia to creative metaphor may be implying many traits that are not equivalent.

In fact, cross-modal sensory associations are pretty damn interesting, and they are robust neurological phenomena; Ramachandran’s work has elsewhere helped to highlight how the human brain might be making this cross modal connections. But synesthesia is a very peculiar cross-modal connection, unlike metaphor in several crucial ways:

First, synesthetic associations are stable: two is always blue to a person, or Monday always has a particular personality, say grumpy.

Second, synesthetic associations are involuntary; there’s no getting around experiencing blue when you count two, and you can’t have a madcap Monday if that’s not your association.

Third, synesthetic associations are cross-modal and unidirectional; my sensory conflating between number and personality does not switch but keeps to a particular pairing of sensory channels, and it only tends to work in one direction. Two is blue, but it doesn’t necessarily suddenly seem to exist in a particular space or develop an impatient personality. And I don’t perceive the reverse: perceiving ‘two’ when I see blue.

Fourth, synesthetic associations are idiosyncratic; even if we’re both color synesthetes, you and I will associate different sensory qualities to letters or words (‘no… “T” is not mauve; it’s lavendar!’).

Fifth, synesthesia, by definition, associates sensations from different sensory channels.

Finally, as Ramachandran himself argues (see Ramachandran & Hubbard 2001a), synesthesia is a perceptual effect, not a memory association, a symbolic link, or an analogy.

Metaphor has none of these traits: it is unstable and varies widely; associations are voluntary, even creative; and metaphor can be crossmodal, but it does not always flow from one channel into a specific other one. Unlike synesthesia, metaphor is typically used in communication and might even be considered ineffective if the association does not successfully communicate to an audience. And metaphors very frequently operate within a single sensory channel, for example, highlighting similarity in visual sensations or sounds. Finally, and perhaps most importantly, metaphor is not perceptual — metaphoric analogy may highlights perceptual qualities, but it is driven by elective choices to highlight qualities that may involve symbolic meanings or create meaningful analogies.

Unlike synesthesia, metaphor is the creative ability to summon up multiple associations to highlight different characteristics; far from being compulsory, many of the most evocative metaphors are novel and unexpected, and they are motivated by some perceived similarity, unlike the arbitrary, compulsory associations made in synesthesia.

Ramachandran himself would no doubt emphasize these differences if asked to contrast synesthesia with metaphor. For example, in their piece on synesthesia in Scholarpedia, Ramachandran and David Brang write:

The link between synesthesia and metaphor (Ramachandran & Hubbard, 2001b) has already been alluded to. The nature of the link remains elusive given that synesthesia involves arbitrarily connecting two unrelated things (e.g. color and number) whereas there is a non-arbitrary conceptual connection between Juliet and the sun. One potential solution to this problem comes from realizing that any given word only has a FINITE set of strong first order associations (sun = warm, nurturing, radiant, bright) surrounded by a penumbra of weaker second order associations (sun = yellow, flowers, beach, etc.) and third and fourth order associations that fade way like an echo. The overlapping region between two halos of associations (e.g. Juliet and the sun; both are radiant, warm and nurturing) – the basis of metaphor- exists in all of us but is larger and stronger in synesthesia as a result of the cross-activation gene. In this formulation synesthesia is not synonymous with metaphor but the gene that produces synesthesia confers a propensity towards metaphor. A side- effect of this may be that associations that are only vaguely felt in all of us (e.g. masculine or feminine letters or good and bad shapes produced by subliminal associations) may become more explicitly manifest in synesthetes, a prediction that can be tested experimentally. For instance most people consider certain female names, e.g. Julie, Cindy, Vanessa, Jennifer, Felicia, etc. to be more “sexy” than others e.g. Martha and Ingrid. Even though we may not be consciously aware of it, this may be because the former involve pouting, tongue, lips etc. with unconscious sexual overtones. The same argument would explain why the French language is often thought of as more sexy than German. It might be interesting to see if these spontaneously emerging tendencies and classifications are more pronounced in synesthetes.

In this passage, I think Ramachandran and Brang recognize differences, highlight some similarities, but then posit an improbable ‘gene the produced synesthesia’ that also ‘confers a propensity towards metaphor.’ Although much of the research leading up to this passage is persuasive, this is where I draw the line.

A more promising approach to thinking about how these intriguing patterns of association (like names being ‘sexy’ or shapes being ‘kiki’ or ‘booba’) arise consistently and remain stable is not so much to look at synesthesia, in my opinion, but to look more closely at the phenomenology of these sensations. For example, Ramachandran and Brang describe how movements of the mouth might make certain names sound ‘sexy’; the easier explanation is to look to these movements, not to point to synesthesia, which typically involves arbitrary, unimodal sensory associations.

In other words, in this case, the explanation might be more phenomenological than neurological, as is the case with much of metaphor. Metaphors are compelling to us, and may successfully communicate, because they usually focus on some sensory or conceptual association, not because, like synesthetes, we invariably and compulsively associate the metaphor with the reference. (And the phenomenological explanation wouldn’t need to ignore the fact that the same names likely aren’t sexy in every language…)

One of the things that makes metaphors work is that, when we share them, they are persuasive to other people because those people, too, can perceive the analogy. Synesthetes don’t associate things because they share some resonant perceptual quality (that is, to anyone BUT the synesthete). In fact, even synesthetes themselves don’t agree on what things are linked when they have the same sort of synesthesia; not all graphemes think three is red. None of this would be news to Ramachandran, who knows far more about synesthesia than I ever will. It’s just that he thinks synesthesia is a useful metaphor for metaphor; like any metaphor, however, we can disagree about whether it’s a good one. The fact that it produced conjectures of a shared metaphor-synesthesia gene suggests to me that it’s not one I want to employ.

References

Hubbard, Edward, and Vilayanur S. Ramachandran. 2005. Neurocognitive Mechanisms of Synesthesia. Neuron 48 (3): 509-520.

Ramachandran, Vilayanur S., and Edward M. Hubbard. 2001a. Neural cross wiring and synesthesia. Journal of Vision 1(3):67 doi:10.1167/1.3.67

Ramachandran, Vilayanur S., and Edward M. Hubbard. 2001b. Synaesthesia: A window into perception, thought and language. Journal of Consciousness Studies 12(1): 3-34.