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.