Aesthetics for Birds

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Are There Objects of Olfactory Perception?


Photograph of Clare Batty

What follows is a guest post by Clare Batty. Clare is Associate Professor of Philosophy at the University of Kentucky. She received her B.A. (Hons.) in Philosophy from Simon Fraser University in 1999, and her Ph.D. from MIT in 2007.  She works primarily in the philosophy of mind and, in particular, the philosophy of perception. Her current research focuses on olfactory experience. Her recent publications include “Olfactory Objects” (forthcoming, Perception and is Modalities, ed. S. Biggs, D., Stokes and M. Matthen, OUP), “The Illusion Confusion” (Frontiers), and “Smelling Lessons” (Philosophical Studies). 

I want to start with a disclaimer.  I do not work in aesthetics.  Some of my future projects, however, will move toward discussions of olfaction and aesthetics.  What I want to do in the entry is fairly simple.  I want to draw some connections between what philosophers of perception, and the empirical researchers they draw from, discuss and show how that research might help, or at least relate to, some of the challenges faced by an olfactory aesthetics.  So, this post may be a little less ‘aestheticsy’ than usual; but it will hopefully be interesting and/or helpful.  I presented these thoughts at the ASA in San Diego, so for those of you that attended that talk, here they are again in a different medium.

I take that the following claim is safe to assume:  olfactory experience breeds aesthetic evaluation.  My use of ‘breeds’ here indicates that, in some sense, olfactory experience  provides evidence for aesthetic judgment.  At minimum, we certainly judge smells (qua properties) for their pleasantness or unpleasantness.  And we have a whole host of predicates at our disposal which we apply to those smells in lending evidence to, or at least further describing, those judgments—e.g., foul, rank, pungent, fragrant, floral, fruity, earthy, among others.  We also judge combinations of smells in the same way.  The perfumer’s task is a prime example of this; but we ‘everyday folk’ make these kinds of judgments as well, although the stock of predicates we employ in making them is arguably less rich.  For example, for me, I make such a judgment whenever I walk into a bath and body shop.  The combination of the smells in those stores I find be very unpleasant—overpowering.  On their own, when I bring individual soaps up to my nose, I can judge the smells of individual things to be pleasant (or perhaps unpleasant, as not everything is to my taste).  But, as a whole, I judge the combination to be unpleasant.  Judged pleasant or unpleasant, though, examples of combinations of smells are ubiquitous in everyday life.  Indeed, they are unavoidable, as just about everything in our environment smells some way or another.

So far I have only drawn attention to the fact that we make aesthetic judgments about the properties that we encounter in olfactory experience.  But, does that truly capture the nature of those judgments—and, indeed, the nature of olfactory experience?  In particular, given that we often make aesthetics judgments about the objects presented to us in the other modalities, are there any such objects in the olfactory realm?

One might think that the answer is obviously ‘yes’.  After all, we report things like ‘the lilacs smell beautiful’.  But philosophers haven’t always seemed convinced of this; in fact, some philosophers of mind have suggested that the phenomenology of olfactory experience does not support the view that olfactory experience presents objects.  (Although the remarks are quick, as philosophical discussions have previously been rare, Peacocke, Lycan and Chalmers have suggested that this is so—although Lycan argues, on non-phenomenological grounds, that olfactory experience presents objects.  See my 2010 for further discussion of these remarks.)  Similarly, Larry Shiner and Yulia Kriskovets draw attention to how philosophical discussions of aesthetics have avoided olfaction or have relegated it to the ‘merely sensuous’.  They cite Kant, Hegel and, more recently Scruton, as advocates of the sensational view of olfactory experience and, with that, the view that it is incapable of generating aesthetic appreciation.  On this view, unlike visual experience, where we are able to attend to—or can’t help but attend to—objects and properties in the world, olfactory attention is directed on the olfactory experience itself—and this is no subject of aesthetic judgment.  In this way, as Shiner and Kriskovets characterize it, visual experience is objective or cognitive, while olfactory experience is subjective.  This distinction is similar to several made in the philosophy of perception, but in particular the distinction between world directed and non-world directed (or sensational, as it is usually put) views of perception.  Shiner and Kriskovets reject the Kantian-Hegelian-Scrutonian line; it “simply seems wrongheaded”.  As evidence for this, they claim: “[w]e see no basis in fact that a person cannot contemplate a lemon odor qua object and compare it with the odor of a pear rather than simply contemplate his or her experience of it” (276).  What I want to do here is suggest that some recent empirical theorizing about olfaction bolsters their cause.  But, as I see it, it also preserves what is distinctive about olfaction—especially when compared with vision—and, in doing so, explains at least some of the attraction of the sensational view.

Our guiding question will be, then: is there ever a way that things appear in olfactory experience?  This is a question of apparent objects, or what also get called perceptual, or sensory, objects.  An answer of ‘yes’ has it that olfactory experience is object-based.  An object-based view of perceptual experience is a view according to which a perceptual experience not only presents properties in the perceiver’s environment, but attributes those properties to objects.  This is opposed to a feature based view, according to which nothing more is needed to characterize a perceptual experience than an inventory of the properties it presents.  We can view those who have suggested that olfactory experience is merely sensational as suggesting that olfactory experience is feature-based—albeit presenting features of experience.

Until recently, a feature-based model had underwritten most empirical theories of olfactory experience.  Donald Wilson and Richard Stevenson (2006), who I will get to momentarily, call this traditional approach to theorizing about olfaction the Stimulus Response Model, or what I will call the SRM.  There are two core claims of the SRM: (1) that an analysis of olfactory experience is exhausted by an account of how the particular features of the stimulus and/or receptor site are presented in experience, and (2) that olfactory experience is analytic—i.e., that the various features of a chemical stimulus (those that trigger receptor excitation) and/or receptor type will map onto features of the resulting experience.  The assumption of this model, then, is that, in olfactory experience, you simply smell that a set of properties are instantiated.

Recently, however, Wilson and Stevenson have argued that this model of olfactory experience is misguided.  This is because, rather than being analytic, olfactory experience is largely synthetic.  That is to say, the various properties of the stimulus produce a largely irreducible experience.  In order to see what they mean, consider one of their examples.  Much of what we encounter and recognize with our noses are chemical mixtures. The stimulus that gives rise to the ‘coffee’ olfactory experience is such a mixture.  Sniffing coffee provides a unique kind of olfactory experience; but it is not one where we are able to discriminate the over 600 compounds that constitute the coffee odor.  As it’s been noted in the empirical literature, it is now commonly accepted that even the experts among us are only ever able to distinguish three or four of the major components that constitute a given odor.  So, although it can fail to be wholly synthetic in this minor way, olfactory experience isn’t anything like what we should expect if the SRM is true.  It is, for the most part, incapable of being broken down into the components that the SRM posits for it.

In place of the SRM, Wilson and Stevenson propose their own Object Recognition Model, or ORM.  (It must be noted that I have critically responded to aspects of the ORM in previous work.  But, for the sake of drawing interesting connections to aesthetics, I set those aside.  They do not affect the connections that I would like to make here, but I would be happy to talk about them in the discussion.)  There are three core claims of the ORM: (1) that olfactory experience presents a “wholistic, unitary percept”, (2) that these percepts constitute the presentation of “olfactory objects”, and (3) that olfactory experience is aspatial.  According to Wilson and Stevenson, claims (1) and (2) draw on the synthetic nature of olfactory experience, and I will say something more about them momentarily.  For the sake of this discussion, I will take (3) for granted.  Some may disagree with (3), however, noting that we can track the boundaries of an odor in the vicinity.  I take it that this kind of active experience is not what Wilson and Stevenson are referring to when they claim that olfactory experience is aspatial.  They mean the ‘inactive’, mere sniff, experience.  And this is what makes the ORM truly interesting—and helpful for Shiner and Kriskovets.  Because, even if we grant that (3) is true, Wilson and Stevenson argue that olfactory experience presents objects—objects that are not only individuated by experience but also capable of reidentification or recognition.

For now, then, let’s to (1) and (2) and consider again their coffee example.  When we smell the coffee, we are presented with a “wholistic, unitary percept”, incapable of being broken down into more than three or four identifiable component features—if at all.  According to Wilson and Stevenson, these unitary percepts are not simply conjunctions of those component features; rather, they are olfactory objects to which olfactory experience attributes certain features.  Given that Wilson and Stevenson also refer to these objects as ‘odor objects’, it is safe to assume that they take these perceptual objects to correspond to odors—collections of volatile, airborne molecules.  In the coffee case, we are presented with what I will call a ‘coffee object’.  Other examples they give are: the odor objects of camembert cheese and book.  But why think of these percepts as the presentation of olfactory objects? 

As Wilson and Stevenson note, the incredible amount of processing that goes on at the olfactory receptors (remember over 600 components) is made even more impressive when we consider the fact that, outside of the lab, our olfactory environment is very complex.  As I drew attention to above, nearly everything smells.  Our noses are barraged with other molecules than those given off by the coffee.  Yet, we are able to smell coffee.  How does olfactory experience achieve this feat?  According to Wilson and Stevenson, over time, the olfactory system builds up a store of templates in the olfactory cortex of patterns of receptor input.  Once stored, they allow the system to recognize those patterns against variable arrays of receptor input. And, according to Wilson and Stevenson, this kind of processing endows us with important discriminatory abilities—for example, the ability to smell coffee even though there are other smelly things about.   Call this phenomenon ‘experiential prominence’.  Contributing to these discriminatory abilities are learning and memory. Learning and memory allow for further influences such as attention, expectation and cross-modal influences.

According to Wilson and Stevenson, experiential prominence amounts to figure-ground segregation.  In turn, figure-ground segregation is, according to them, the “defining feature of perceptual objecthood”.  This is not a rare claim.  It is echoed by Shoemaker in the philosophical realm: “[s]ense perception affords ‘identification information’ about the object of perception.  When one perceives one is able to pick out one object from others, distinguishing it from the others by information, provided by the perception, about both its relational and its nonrelational properties (205)”.  In the visual case, of course, figure-ground segregation is achieved spatially.  But, for Wilson and Stevenson it is achieved aspatially.  I gave their reasons for thinking so above—namely, the phenomenon of ‘experiential prominence’.  Olfactory experience isolates target objects in virtue of a ‘match’ between incoming information about the stimulus at the receptor site and stored patterns of receptor input in the olfactory cortex.  This allows for a filtering of the information generated at the receptor site.  Certain odors, then, stand out from others and, given the template model, can be recognized more easily when they are encountered again.  In terms of the ORM, these achievements of experiential prominence allow for the perceived persistence of an olfactory objects as well as, it would seem, for the ability, as in the visual case, to track an object through space (in this case an odor) as when we search for its source. 

According to the ORM, then, our guiding question gets an affirmative answer.  There is a way that things appear in olfactory experience.  Although a sensational view might seem tempting, the modified ORM has it that there are objects of olfactory appreciation eligible for the attribution of predicates.  Although they may not be as complex as visual objects—consider again their synthetic nature—Wilson and Stevenson claim that their olfactory objects bear the hallmark features of sensory objects.  We can now see how the ORM is relevant to, and helpful for, Shiner and Kriskovets.  Recall that, in the response to the sensational view, they claimed: “[w]e see no basis in fact that a person cannot contemplate a lemon odor qua object and compare it with the odor of a pear rather than simply contemplate his or her experience of it”.  If the ORM is correct, then there is indeed no basis in fact.  On the ORM, the lemon odor—a “wholistic unitary percept”—is indeed a presented object, capable of being distinguished from the pear odor, of being perceived as persisting, and of being tracked across space.  All of this can be achieved, on the ORM, even though those objects are not, in a sniff, ever presented as spatial.  To be sure, Wilson and Stevenson claim that odor objects are presented as external to a perceiver; it’s just that they are not presented in space any more determinately than that.  (For philosophers who have discussed this aspect of olfactory experience see Batty 2010 and Richardson 2013.)  And, as I want to suggest, this lack of determinate spatial representation, captured by the ORM, explains why some might have thought that olfactory experience is purely sensational.  The visual model has ruled philosophy, after all.  If vision is taken as the paradigm of spatial representation—indeed representation in general—then it is no wonder that some have thought that olfactory experience is merely sensational.  But the ORM rejects this paradigm, as do most philosophers who work on olfaction.  As the ORM claims, rather than being simply lacking in some way, olfactory experience is distinctive.  It is aspatial and yet individuates objects.  For aesthetics, then, the ORM provides an opportunity—an opportunity to explore what has felt different about the idea of an object of aesthetic appreciation for the olfactory case while providing reasons for thinking that it is not an empty notion.

Of course I have said nothing about the nature of our olfactory aesthetic judgments other than that, on a widely accepted empirical view of olfactory experience, they have objects.  And I do recognize that there are more questions to ask—in particular questions about the aesthetic properties themselves and their relation to what scientists tell us is a rather limited supervenience base of discriminable properties.  I will, however, leave that as food for thought. 

Batty, C.  2010.  “A Representational Account of Olfactory Experience,” Canadian Journal of Philosophy 40: 511-538.

Richardson, L.  2013.  “Sniffing and Smelling,”  Philosophical Studies 162: 401-419.

Shoemaker, Sydney.  1996.  “Qualities and Qualia: What’s in the Mind?”  In The First Person Perspective and Other Essays.  New York: Cambridge University Press.

Wilson, D. A. and R. J. Stevenson.  2006.  Learning to Smell: Olfactory Perception from Neurobiology to Behavior.  Baltimore: Johns Hopkins University Press.

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