Strange games of the olfaction: learning to recognise aromas How can we learn to recognise odours, to identify them and memorise them by name? Let us discover this process and learn some simple, but useful exercises to train our olfaction. And above all to train our memory
Think for a moment about your life: when you were young, you were taught to modulate sounds in order to communicate your thoughts through your voice; then you were trained to coordinate your movements in order to walk in an upright position; and at school your brain was trained to carry out logical operations of increasing difﬁculty. But when has anyone ever thought you to train your olfaction? One may become a great musician by practising for many hours a day and repeating the same exercise millions of times. Another may become a supple ballet dancer or an able gymnast: but who has ever followed a similar path in order to express their olfactory talent? The olfaction, as we have seen, is truly unique from a psycho-physiological point of view, but it cannot be blamed if it fails to respond to our requests, when we want to use
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it with awareness. It is not uncommon for a perfumer or ﬂavorist to know how to identify correctly, and with total certainty, thousands of different scents, attributing semantic labels to each of them: are these people naturally gifted? Perhaps, but the research has demonstrated that prolonged training is also of great importance in developing such an ability. The olfactory threshold of these experts is usually lower than the average for odours that are known to them (which means they perceive more); for all other odours, however, they are equal to us mere mortals. The ﬁrst secret to learning and recognising odours, therefore, is training.
Using authentic odours Any substance which is capable of having an effect on the olfaction may be used to
train this sensory faculty and to increase the number of semantic labels with which to describe perfumes and aromas. However, it is important to use authentic odours: if I wish to learn to recognise butter using diacetyl, the main ingredient constituting butter aroma, I will probably not be able to identify real butter when it is put in front of me. Sensory analysis often uses olfactory standards as they are useful in establishing the presence of speciﬁc or generalised anosmia (the inability to perceive odours), or, more simply, to perform entertaining aroma tests. Thanks to this experiment, it has been noted that often diacetyl is not described as butter, but as rancid. The same can be said of b-ionone, the main constituent in violent perfume, which is often identiﬁed as fresh paint. The list goes on. The fact is that odours are memorised as single events: the aroma of a banana is not given to it by isoamyl acetate, even if it is its major constituent, but by the around 250 different molecules which, in speciﬁc proportions, are perceived by our olfaction as “banana”. By removing one part of it, the aromatic puzzle is rendered meaningless, like an incomplete ideogram. Everyday we come into contact with dozens of odours and we can train ourselves to codify them semantically. When you get on the bus, rather than entering a house or theatre, try to describe the odours you perceive there. If you approach an interesting person, try to catch their scent, going beyond the judgement of good/bad, and try to associate such scent to something you have already smelt, to another person or another situation in your life in which you perceived the same odour. When you eat something, try to guess the ingredients separately, trying to remember the speciﬁc aroma of each of them. These are useful exercises to practice when learning to recognise odours.
Using our episodic memory Odours activate our episodic memory, not our semantic memory, and therefore they evoke situations and events, not names of things. As the olfaction mainly uses this episodic memory, in the majority of cases an odour will be expressed as an event or as
an element that was present or characterised that event. It will be a lot more difﬁcult to receive a response if you ask yourself “what is that smell?”, rather than “where have I smelt this perfume before?”. The path you indicate to your mind by asking the second question is much more likely to create the possibility of recovering an episode of your history and, from this, a place and ﬁnally an odour. Similarly, if you wish to discover the spicing of a wine, do not look for cinnamon, cloves, pepper, nutmeg and the like, but imagine yourself the moment you enter your house, turn your mind to where you keep the spices, see yourself as you open the cupboard, watch yourself as you open the jars in which spices are stored. Does the odour you were looking for exist there?
The hierarchy of associations, from semantic labels to emotions If a word is available to identify something, it will be more easily distinguishable from other things: this is how we can apply the Sapir Whorf hypothesis to sensory analysis. Now, the ﬁrst operation in an odour-learning activity is to start by giving a name to what we perceive, in order to memorise it through a double codiﬁcation (a semantic label combined with an olfactory engram), thus ﬁxing it in our memory using several anchors, the most important of which is emotion. Let’s take an orange: a real, beautiful, ripe orange. We bring it to our nose, and perceive its scent. We take a few seconds while we repeat the name “orange” to ourselves. We have thus linked the olfactory engram to a semantic label with an anchoring point. We can go through the same process by looking at the orange, and ﬁxing its image in our memory: there are now two anchoring points, even if they are somewhat weak, belonging to two very distant areas of our brain. Let us take a step forward: we smell the orange perfume, we look at the fruit and repeat its name out loud. There are now three anchoring points, yet they are still weak. Now we repeat the three phases of the operation, adding a fourth one: after having
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repeated its name, while trying to perceive its perfume thoroughly, we search within our memory to see if we have ever been in the presence of a tree laden with oranges in the splendid surroundings of Southern Italy. We now have four anchoring points, the fourth of which is very strong as it is episodic. Now we take the last step: in our memory the visit to the orange grove fortunately ended in an unforgettable evening. Here is the emotion, the best way of ensuring that any perfume stays ﬁxed in our memories.
Putting aromas in cages Our body possesses more than one thousand types of specialised receptors, capable of distinguishing between more than 400,000 aromas (perhaps more) different in quality and intensity: since when has our brain had such a vocabulary at its disposal? Why then should we not assign aromas to categories of varying levels? When you perceive a smell, try to think to which category it could belong: ﬂoral, fruity, vegetable, spicy, empyreumatic (toasted/ burnt) or, more generically, chemical/ biological (oxidised, caseous, sulphurous, putreﬁed)? If you decide that what you perceive belongs to the fruity category, does it belong to the fresh fruit sector, like apples and cherries, or the dry fruit sector, like walnuts or hazelnuts? If it belongs to the fresh fruit sector, could it be a fruit with seeds (apples, bananas), or a stone fruit (cherries, apricots)? By following an aroma classiﬁcation process on more than one level, a name should come to your mind much more easily.
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Recognising the two faces of each aroma We have discussed the ability of odorants to express themselves in tones that are decidedly different depending on their concentration; however, we have not yet mentioned that aromas can show a completely different face depending on whether they are perceived through the nasal or the retronasal channel. In the second case, synesthesic conditions are generated in which taste and tactile perceptions also intervene, either directly or indirectly. Mint is easy to recognise because, already at an olfactory level, it produces a real odour which is perceived by the olfactory mucosa and it also produces a tactile stimulus which conveys the idea of freshness. However, the aroma of liquorice is more easily perceived in the mouth if associated with the classic bitter. This aside, in the mouth all odorant molecules are kept in a warm environment which, characterised by a constant ﬂow of air (retronasal olfaction), can signiﬁcantly increase their concentration, thus making their identiﬁcation easier. It is true that it is not always possible to put the source of the odour into our mouths (and in some cases, it is certainly wiser not to), so it is worth dedicating a great deal of attention to the odorants acquired via the orthonasal olfactory function: learn to breathe with your nose, and not with your mouth, blocking off one nostril occasionally to see how the smell differs by having only one nostril open.
Luigi Odello firstname.lastname@example.org