Are olfactory objects spatial?

by Solveig Aasen – Associate Professor of Philosophy at the University of Oslo

On several recent accounts of orthonasal olfaction, olfactory experience does (in some sense) have a spatial aspect. These views open up novel ways of thinking about the spatiality of what we perceive. For while olfactory experience may not qualify as spatial in the way visual experience does, it may nevertheless be spatial in a different way. What way? And how does it differ from visual spatiality?

It is often noted that, by contrast to what we see, what we smell is neither at a distance nor at a direction from us. Unlike animals such as rats and the hammerhead shark, which have their nostrils placed far enough apart that they can smell in stereo (much like we can see and hear in stereo), we humans are not able to tell which direction a smell is coming from (except perhaps under special conditions (Radil and Wysocki 1998; Porter et al. 2005), or if we individuate olfaction so as to include the trigeminal nerve (Young et al. 2014)). Nor are we able to tell how a smell is distributed around where we are sitting (Batty 2010a p. 525; 2011, p. 166). Nevertheless, it can be argued that what we smell can be spatial in some sense. Several suggestions to this effect are on offer.

Batty (2010a; 2010b; 2011; 2014) holds that what we smell (olfactory properties, according to her) is presented as ‘here’. This is not a location like any other. It is the only location at which olfactory properties are ever presented, for olfactory experience, on Batty’s view, lacks spatial differentiation. Moreover, she emphasises that, if we are to make room for a certain kind of non-veridical olfactory experience, ‘here’ cannot be a location in our environment; it is not to be understood as ‘out there’ (Batty 2010b, pp. 20-21). This latter point contrasts with Richardson’s (2013) view. She observes that, because olfactory experience involves sniffing, it is part of the phenomenology of olfactory experience that something (odours, according to Richardson) seems to be brought into the nostrils from outside the body. Thus, the object of olfactory experience seems spatial in the sense that what we smell is coming from without, although it is not coming from any particular location. It is interesting that although Batty and Richardson claims contrast, they both seem to think that they are pointing out a spatial aspect of olfactory experiences when claiming that what we smell is, respectively, ‘here’ or coming from without.

Another view, compatible with the claim that what we smell is neither at a distance nor direction from us, is presented by Young (2016). He emphasises the fact that the molecular structure of chemical compounds determines which olfactory quality subjects experience. It is precisely this structure within an odour plume, he argues, that is the object of olfactory experience. Would an olfactory experience of the molecular structure have a spatial aspect? Young does not specify this. But since the structure of the molecule is spatial, one can at least envisage that experiencing molecular structure is, in part, to experience the spatial relations between molecules. If so, we can envisage spatiality without perspective. For, presumably, the spatial orientation the molecules have relative to each other and to the perceiver would not matter to the experience. Presumably, it would be their internal spatial structure that is experienced, regardless of their orientation relative to other things.

The claim that what we smell is neither at a direction nor distance from us can, however, be disputed. As Young (2016) notes, this claim neglects the possibility of tracking smells over time. Although the boundaries of the cloud of odours are less clear than for visual objects, the extension of the cloud in space and the changes in its intensity seem to be spatial aspects of our olfactory experiences when we move around over time. Perhaps one would object that the more fundamental type of olfactory experience is synchronic and not diachronic. The synchronic variety has certainly received the most attention in the literature. But if one’s interested in an investigation of our ordinary olfactory experiences, it is not clear why diachronic experiences should be less worthy of consideration.

Perhaps one would think that an obvious spatial aspect of olfactory experience is the spatial properties of the source, i.e. the physical object from which the chemical compounds in the air originate. But there is a surprisingly widespread consensus in the literature that the source is not part of what we perceive in olfaction. Lycan’s (1996; 2014) layering view may be an exception. He claims that we smell sources by smelling odours. But, as Lycan himself notes, there is a question as to whether the ‘by’-relation is an inference relation. If it is, his claim is not necessarily substantially different from Batty’s (2014, pp. 241-243) claim that olfactory properties are locked onto source objects at the level of belief, but that sources are not perceived.

Something that makes evaluation of the abovementioned ideas about olfactory spatiality complicated is that there is a variety of facts about olfaction that can be taken to inform an account of olfactory experience. As Stevenson and Wilson (2006) note, chemical structure has been much studied. But even though the nose has about 300 receptors ‘which allow the detection of a nearly endless combination of different odorants’ (ibid., p. 246), how relevant is the chemical structure to the question ‘what we can perceive?’, when the discriminations we as perceivers report are much less detailed? What is the relevance of facts about the workings and individuation of the olfactory system? Is it a serious flaw if our conclusions about olfactory experience contradict the phenomenology? Different contributors to the debate seem to provide or presuppose different answers to questions like these. This makes comparison complicated. Comparison aside, however, some interesting ideas about olfactory spatiality can, as briefly shown, be appreciated on their own terms.

 

 

References:

Batty, C. 2014. ‘Olfactory Objects’. In D. Stokes, M. Matthen and S. Biggs (eds.), Perception and Its Modalities. Oxford: Oxford University Press.

Batty, C. 2011. ‘Smelling Lessons’. Philosophical Studies 153: 161-174.

Batty, C. 2010a. ‘A Representationalist Account of Olfactory Expereince’. Canadian Journal of Philosophy 40(4): 511-538.

Batty, C. 2010b. ‘What the Nose Doesn’t Know: Non-veridicality and Olfactory Experience’. Journal of Consciousness Studies 17: 10-27.

Lycan, W. G. 2014. ‘The Intentionality of Smell’. Frontiers in Psychology 5: 68-75.

Lycan, W. G. 1996. Consciousness and Experience. Cambridge, MA: Bradford Books/MIT Press.

Radil, T. and C. J. Wysocki. 1998. ‘Spatiotemporal masking in pure olfaction’. Olfaction and Taste 12(855): 641-644.

Richardson, L. 2013. ‘Sniffing and Smelling’. Philosophical Studies 162: 401-419.

Porter, J. Anand, T., Johnson, B. N., Kahn, R. M., and N. Sobel. 2005. ‘Brain mechanisms for extracting spatial information from smell’. Neuron 47: 581-592.

Young, B. D. 2016. ‘Smelling Matter’. Philosophical Psychology 29(4): 520-534.

Young, B. D., A. Keller and D. Rosenthal. 2014. ‘Quality-space Theory in Olfaction’. Frontiers in Psychology 5: 116-130.

Wilson, D. A. and R. J. Stevenson. 2006. Learning to Smell. Olfactory Perception from Neurobiology to Behaviour. Baltimore, MD: The John Hopkins University Press.