Analysis: The part of our brain that processes smell is also the part that processes emotions and memories
The scent of freshly cut grass reminds you of playing with friends on summer holidays, the smell of a roast brings back good times at family dinners and the distinct odour of cheap body spray conjures up the image of being in a classroom in secondary school. Whatever the memory, many of us will have been reminded of certain feelings and emotions by smell alone. While we rely on sight and hearing to navigate the world, smell is a powerful sense whose influence is underestimated.
Why scents have such an impact on our emotions and memories is down to how our brains are designed. The section of your brain that processes smell is connected to another part that processes emotions and memories.
"The part of the brain that's doing the conscious processing of olfaction (the sense of smell) when you smell something is the same part of the brain that’s doing two other jobs," explains Dr Rachel Herz, neuroscientist at Brown University. "One is processing emotion and emotional memory, while the other is learning associations and other forms of memory."
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From RTÉ Radio 1's The Ray D'Arcy Show, how taste and smell are interconnected
The link between smell and emotions
How this happens is down to the limbic system - a group of structures in your brain that regulate emotions, behaviour and memory. In particular, the limbic system has two conjoined regions: the amygdala, which processes emotions and emotional memory, and the hippocampus, which is linked to various aspects of learning and cognition.
Your sense of smell is directly connected to these two structures which is why your brain learns to associate certain smells with specific memories. Usually, when a smell conjures up a memory, it’s because the scent is distinctive and unique.
You also have to be able to physically perceive the scent; any smells that are subliminal or subconscious won’t affect us. Sometimes you may not be able to recall the memory associated with a scent, but the emotion tied to it will still emerge.
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From RTÉ Radio 1's The Ryan Tubridy Show, Dr Caro Verbeek speaks about reconstructing smells for museums that are associated with historical events.
"It can be the case that a feeling will just come back to you, where you wonder why you’re suddenly getting a nostalgic, wistful sensation," adds Herz. "You may not realise it is because you're washing your hands with the soap that your grandmother used to have, but if someone were to tell you what the soap is, you might go 'yes, that’s what’s triggering it’".
Smells are all around us, and we tend to ignore them as scents are invisible, but every now and again, specific smells will trigger particular memories. The smell of a Sunday roast or Christmas dinner can conjure pleasant memories, but it can be tied to other associations, like the emotional comfort of being with your family.
"Food is a comfort and a nutritional necessity, so it’s emotional in and of itself," she said. "Especially the foods that our caregivers, like our family, make for us, as it makes us feel taken care of."
Creating associations through smell
While we might not think much about smell in our daily lives, much of our lives would be affected if we lost that sense. One example is that flavour is mainly determined by smell, which is why food can taste bland when you have a cold and your nose is blocked. When Covid hit, some people reported a loss of taste when in reality it was their sense of smell that was impacted.
You can utilise smell to help with memory and evoke particular emotions. Herz conducted a research study in which participants memorised a list of words in a room with a specific scent. When they were asked to recall them, they recalled more words if the same scent was present than in a room with a different scent or no scent at all.
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From RTÉ Radio 1's Liveline, listeners describe what it was like to lose their sense of smell
You can use this to help you get into a particular mood or recall certain information. Herz recommends picking a novel and distinct scent, one you don’t associate with an existing mood or memory, and practice with that scent.
"Associating what you’re learning with that smell will definitely help you recall it later on, as well as getting into certain emotional states," she explains. "If I want to get myself calm and centred, and I meditate with a certain scent, I can then pull out that scent later without having to spend 10 minutes trying to get into that calm state."
So the next time a memory strikes you, or you’re feeling nostalgic, take a note of what you're smelling. Chances are it's playing a bigger role than you think.
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The views expressed here are those of the author and do not represent or reflect the views of RTÉ
