Sense of smell – how it works miniature version

Every now and then it’s good to refresh our memory about the basics when it comes to scents. Brands are more or less trendy, there are seasonal perfume launches and top ten lists and marketing budgets. Then there is the smell of rain, of summer, of skin, of coffee beans. Sometimes it is easy to forget how it is all connected. So, here is a very short and extremely simplified guide to the sense of smell - or olfactory perception. It is not necessary to know these things to appreciate perfume, but having some rough insight into the links between scents and our body and brain makes things more interesting and the search for perfume or candles more conscious.

Nothing is arbitrary, and so much of how we perceive scents has to do with the construction of the brain.

First of all, we are all affected by scents around us. This has nothing to do with preferences or interest. We are programmed to take smell seriously as it has initially been a survival tool used to sense danger and to find suitable partners for reproduction. We might not find ourselves in the situations where it is the most important tool anymore, and much has changed. For example we select partners according to various criteria and we have dates written on food packages so we don’t necessarily smell them to see if they are still ok. But our brain is still built the same way and our instinct is to trust the information that smells gives us. 

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When we inhale a scent travels in odor molecules. It goes up through the nose (it is possible to have two separate impress, that is one through each nostril) and to olfactory membranes inside the nose. The odor molecules match receptor cell sites that line the olfactory epithelium. When stimulated by odor molecules the nerve cells send impulses to the olfactory bulb in the brain which forwards  the impulses to the gustatory center (where the sensation of taste is perceived), the amygdala (where emotional memories are stored), and other parts of the limbic system of the brain. The sense of smell is the only one of our five senses that is directly linked to the limbic lobe of the brain which means that what we smell goes directly to the brain's centers for memories and emotions.

The limbic system is also directly connected to the parts of the brain that control heart rate, blood pressure, breathing, memory, stress levels and hormone balance. What we smell goes right to the parts of the brain that are related to emotions and memories. We might intellectualize olfactory impressions, but we can never avoid the highway they take to our feelings. This is one of the reasons why a conscious use of smells, for example in professional contexts, is a very powerful (and underestimated) tool.

What scents we prefer is to a large extent based on memories and cultural preferences. Scents trigger old memories and suddenly something creates a feeling of safety because it reminds us of childhood. Or the opposite – a scent can take us back to an unhappy feeling because it triggers a sad memory. Scents have been used in therapy to activate traumatic memories among war victims so that these memories can be processed. Sometimes we are not even aware of the strong associations between a smell and a memory until we experience them. It is noteworthy here that what we perceive as a bad smell is something that we are taught. This is a good reminder for parents with small children – the children do not evaluate the smells until you teach them. Why not let them keep discovering for a while longer before drawing the map?

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The associations are subjective. There are however some general scent-related effects that seem to affect us in a similar way. A citrus smell will boost our energy (try smelling a lemon when you get sleepy in your office the afternoon). Lavender has been used in studies that indicate that it improves our cognitive ability. Benzoin, vanilla and sandal wood calm and balance. You might not think this matters or that it is obvious – but do you really think about how your perfume affects different situations at work? A brain storm and a crisis meeting benefit from entirely different smells. You benefit from different smells in the morning compared to when you need to unwind. 

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Smell the attraction
A strange mash-up of procreation science and marketing clichés has created some sort of hype around fluffy explanations and theories on the sense of smell and attraction. You will for example hear the word “pheromones” thrown like some sort of dating dart. It is not that easy. Olfactory perception does indeed play an important role in attraction but various aspect of contemporary life has changed that game a bit. We have over-washed bodies, on-paper-criteria and online dating for example. It is true however that olfactory perception has had the purpose to help us select appropriate partners based on information about immune systems communicated through pheromones. But let’s leave it at that for now and I promise to do a post on pheromones later. I would suggest however that when you select a perfume based on your desire to meet Someone that you want to keep meeting: don’t go looking or asking for perfumes that “smell sexy”, look for perfumes that add to you smelling like you.

There is an infinite amount of aspects to talk about when it comes to our sense of smell and our body and mind. I have mentioned some of these in my posts about scent and memories, and the posts on specific ingredients. Please feel free to share insight or questions by commenting below or send an e-mail.

Olfactory disorders

Last but not least, our olfactory perception is not something that we should take for granted. Many people suffer from an olfactory disorder and this can be quite problematic. Here are some of the most common disorders of smell.

• Anosmia – inability to smell 
• Dysosmia – things smell different than they should 
• Hyperosmia – an abnormally acute sense of smell
• Hyposmia – decreased ability to smell 
• Phantosmia – "hallucinated smell," often unpleasant in nature