Image above: Our olfactory sense and our long-term memories are tied together. To track places lost, I have collected boxes; the smell inside triggers my memory.

Cats are more attached to places than to their masters, so people say. Although I doubt that this is really true literally, felines are certainly attached to their territory. Cats, dogs, as most mammals, recognize their place by its scent – which they also enrich with their own pheromones.

When we humans smell something, that reminds us of some place we have been to, the memoric sensation that is evoked, feels often like the place in its whole, including everything that took place there. Such a gestalt can have overwhelming power, sucking us into the past. (Now I must not miss to quote Proust here, because it seams you can’t write about memories triggered by aroma without reference to ‘À la recherche du temps perdu’, so here you are.)

Scents cannot be digitized. Because we never smell anything without adding all our long-term memories to the sensation, it is impossible to find a common language that transports how we experience the scent. Other than visual impressions, haptics, temperature, which can be shared verbally with others, our olfactory sensing is highly personal. While I am writing this, I am sitting on the windowsill of my study; the warm air carries the smell of lilacs to me. But although I can presume why people are fond of this flavor, I do not have much associations with it; I can rationalize the connection of spring blossoms with warm and pleasant weather, however lilacs are obviously not connotated in an emotional way for me.

Nostalgic souvenirs

When my grandmother died, and we cleared her house, realizing it would be the last time to smell the place was also when I bacame aware I would never come back, at all. So I kept a box with stationary as a scent capsule. Yet also this smell will fade away, and with it the access to those long-term memories.

Nostalgia is directly tied into our olfactory memory that way. Our limbic system stores complex emotional landscapes together with the smell we experienced there. These memory-compexes are processed pre-consciously (it is a very old part of our brain that we share with all vertebrae since the carbon age); and because the brain’s layers are not working independently, our consciousness is immediately involved, primed with emotions, and adds the rational context to the emotional scenery.

I am generally not prone to nostalgia. Nevertheless I love to evoke those complex memory-scenieries arbitrarily. I have therefore collected a couple of specimen – far from sufficent to cover my life so far – but anyway. Does anybody else do this? Has anyone heard of doing this systematically? I would love to hear about this!

Semiologic approach

Although scents are highly personal, it is interesting to see how specific olfactory sensations are correlated with words. When I was working for Hubert Burda Media, a major print publisher, we we drew a subsample of some 1,500 parfume userers from our 20,000 participants in our large market survey TdW. With partners from the cosmetics industry, we asked the participants to rate more or less arbitrary words we put together on a list (quite similar to Semiometrie). Since we knew the fragrance the participants would usually wear, this allowed for building a dictionary of words related to parfumes prefered. We cross checked: the main olfactory characteristic of the parfume (“fruity”, “clove”, “lavender”, “musty”, … the perfume people have operationalized a typology that way) was correlated to the words ranked positive; and vice versa, ranking a word positive was a good predictor for scent preference of our control group. So it seamed to work. Unfortunately I left my team for a new job (online video – no relation to the cosmetics industry whatsoever), and the research was not carried on.

I still belief that starting with lexical correlates to complex emotional memories is a good way in making the scent sensation more comparable between subjects. At least those words can work as metaphors that we can build a shared image of.

Scent libraries

Smell-samples like my nostagic remnants of aroma carriers when collected systematically soon get very creepy. The East-German Staatssicherheit had amassed thousands of rags from the clothes of dissidents. This intrusive, totalitarian practice was in use in West-Germany, too, however not to such a horrifying extent.

Juan Mari and Elena Arzak with their library of aromas.
(Courtesy of Restaurante Arzak)

A much more pleasant form of scent collection can be found at the restaurant of Juan Mari and Elena Arzak. Situated at the Biscay at San Sebastion, Arzak’s is regarded as one of the best restaurants in the world. Pioneering in molecular cuisine (they call it even cuisine d’investigation), the Arzaks deployed a method, commonly used by perfumers: a library of fragrances to be composed to the aroma like colors on a painter’s palette. Perfumers and master chefs alike manage to synthesize scents arbitarily from basic odors.

Smell tracking

Our olfactory system is thus integral part of our synaesthetic memories. If we could track smells like we can record images with our mobile phone, it would certainly complete our lifelogging efforts. Most fragrances decay quickly when exposed to oxygen. So it does not make much sense to physically store our records. The task would rather be at first to analyse the chemical composition of the smells that surround us, and second to provide means to synthezise the recorded smell-memories anytime later, similar to what perfumers or chefs do by means of their artistry.

An interesting approach was presented by Jenny Tillotson at the Quantified Self Conference in Amsterdam. Dr. Tillotson is designing sensory fashion, that despenses very small doses of parfume according to our body functions. If the device detects stress or anciety, it would provide the person wearing it with a scent, specially designed to sooth the condition. The scent’s composition is customized according to the person’s personal needs. The singular aromas (like lavender, rosemary, citrus, etc.) are suspended on a special chip, a so called lab-on-a-chip, that acts as a miniaturized dispenser.

I think this might be a good path to follow. Of course the task to compose personal parfumes from a set of five or so aromas according to preset parameters is much simpler (complex enough, anyway!) than I full scale analyzer-syntheziser for scent tracking would have to be. So there is a lot to do!

Further reading:

• The fascinating talk by Nobel Prize laureates Linda B. Buck and Richard Axel who found the mechanism by which our olfactory memory is made so personal: “Scents and Sensibility: A Molecular Logic of Olfactory Perception”
• The Foul and the Fragrant: Odor and the French Social Imagination
• Bushid et.al.: Humans Can Discriminate More than 1 Trillion Olfactory Stimuli