The science of scent

We are all well versed in describing our experiences in life, we have a complex language developed for this purpose, however there are some areas where our language is sadly lacking.  In particular these are areas concerned with basic senses, such as smell and taste.  The reasons why we have not developed are complex and not fully understood but one of the main reasons is thought to be because these senses are closer to the deep primitive parts of the brain than they are to our descriptive and language centres.

Primitive senses

Our sense of smell and to a lesser extent taste, are deeply ‘wired’ into the primitive areas of our brains.  These areas, deep in our brains bypass our conscious areas and directly effect our mood, feelings and inner urges.  These feelings are so deep in our brains and so primitive we only become aware of them when they are communicated to our higher senses.  The deeper, more primitive area of the brain (referred to as the ‘Limbic system’) is still not very well understood; all we can really do is say what functions they have and what effect they have on us.

If you look at the diagram of the brain (below) you can see how close the ‘smelling area’ of the nose (the Olfactory Bulb) is to the areas of the brain that are responsible for such deep aspects of our experience such as emotion, fear, well-being and memory as well as sensual and sexual response, in fact the olfactory bulb can be considered part of the Limbic system itself.

Memory and Emotion

The link with memory is well documented and the experience is referred to in the books by (among others) Proust and Nobokov. Many people have experienced this themselves. If one experiences a smell as a child, be it mothers cooking, steam engines or a bloom, and that smell is never experienced again for many, many years and a whiff of the smell is caught again years later; one is immediately ‘transported’ to the time of the first smelling with floods of memories and emotion.  This can be mild or it can be vivid and at times it can catch us quite by surprise.

In fact this deep link is not just a memory effect the scent of a place or a time in our lives has much to do with our overall ‘experience’ or ‘feeling’ of that time and place.  This is quite hidden from our conscious minds and we have to think hard and almost ‘meditate’ to become fully aware of it.  The link between certain flowers or blooms in the home and their effect on people has been well-known by skilled florists for centuries.  Science has long thought that this was mainly from visual impact and purely psychological reasons. 
However from the diagrams above it is seen how the smell of flowers can directly influence our moods, emotions and other behaviour; something to be taken very seriously!  This is made all the more interesting, as the sense of smell seems to ‘bypass’ our conscious minds to a large extent so our moods and feelings are being influenced without us being aware of it.

Certain studies measuring brain activity via EEG (electroencephalogram) has shown that certain exotic-smelling blooms can promote the generation of alpha-waves (linked to relaxation and creativity) and some herbs with sharp odours can promote brain activity associated with alertness.

Describing Scent

We mentioned that due to the sense of smell ‘bypassing’ our consciousness we have not really developed ways of expressing what we are smelling in useful (and empirical) terms. Because we lack the basic language we have to liken smells that are new to us to something that we all recognise.  So when we smell something that smells exotic, heady and tropical we can simply it smells a bit like Jasmine. The real effect here is demonstrated in the above sentence.  When one sees descriptions like the first part (exotic, heady etc) it can only convey some of the characteristics of the odour and one has trouble really picturing what is meant. However when one reads ‘like jasmine’ one immediately can picture the smell of Jasmine and almost smell it.

It is worth noting that this is true of taste and colour also (try describing the colour ‘red) sometimes this can sound a bit ridiculous (look at wine taste descriptions) but it really is an efficient way to describe things.  Most perfumers will use a mixture of the first kind of description exotic, heady, etc along side the second ‘likening’ type of description.  For example when smelling two varieties of Scented Narcissi from The Isles Of Scilly 

Variety; Hugh Town:

With its crisp, clean, green top-notes, this bloom gives the impression of the sea-side and fresh air; whilst the intoxicating body of the fragrance is reminiscent of exotic flowers such as jasmine and ylang ylang.

Variety; Scilly White:

A heady, floral top-note evocative of hyacinth and lilac; with a trace of fresh, green bell pepper supported by a hint of grapefruit.

In both cases we have descriptive language like ‘exotic’ and ‘fresh’ as well as likening the odours to other things like ‘jasmine’ and ‘green bell pepper’.  Describing scent in this way is complex and the perfume industry has developed its own way of describing scent and dividing it up into various types.  Most perfumers with use one of several informal systems of odour description that have evolved over the years.

Feeling Scent

If, as humans we have trouble connecting our language centres to our sense of smell, perhaps there is another way to convey how we perceive scent.  We have seen how close ‘feelings’ such as memory and a sense of ‘experience’ are linked in our brains.  If when we are smelling a scent we close our eyes and allow our thoughts and imaginings to wander it can feel that the scent is directing our thoughts and memories and the feelings and memories that are evoked can be used to describe our experience of the scent.  If we again look at the two varieties of Isles of Scilly Scented Narcissus for an example, this time the odour described using the techniques mentioned above:

Variety; Hugh Town:

This fragrance whisks one back to a warm bright day on the islands: seagulls rising on the wing overhead, sailing ships racing on the breeze, and exotic scents rising from the fields and being caught on the wind.

Variety; Scilly White:

Evocative of soft spring days wandering through groves of lilac trees as the breeze wafts the perfume of fresh lush grass through the air.  The warmth of the spring sun on your face. A feeling of calm and serenity in a beautiful place. 

Although nothing is said about the scent technically the above passages perhaps better convey the effect on the person smelling the bloom.  The experience is based on personal experience and feelings and everyone will have their own ideas, but still this approach can convey the ‘essence’ of the scent and its effect on our moods and feelings.

So we have seen the power of scent and how science is now coming to prove what many of us have know for a while.  We have also seen how scent can affect our deepest feelings without us even being aware of it.  We have seen how scent can be ‘experienced’ and described in several ways.  All of the ways have a place and they can be used separately to convey the scent of a perfume, bloom or even the collective scent of a whole arrangement and how it makes us feel.

John D Heffernan & Hazel MacTavish-West

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