January 18, 2016

The Science of Smell

“Smell is the most direct of all our senses,” wrote Diane Ackerman in her 1990 book “A Natural History of the Senses.”

Studies continue to show our sense of smell to be the most complex, sophisticated and powerful of all our senses. Over 8 million sensory receptors enable our noses to pick up an enormous range of scents and fragrances. In fact, research from the early 20th century found that the human nose can recognize over 10,000 distinct smells.

More significant, though, is the fact that our sense of smell is intimately tied to our long-term memory. Ever notice that catching a whiff of a familiar smell—a perfume or a favorite meal from childhood—can evoke strong memories from years, even decades, ago? Because of this, the smells we encounter can greatly affect our mood and outlook. But why is smell so hard to quantify, and how does smell affect our lives?

the science of smell

Image: Flickr

The indescribable nature of smell

“Smells coat us, swirl around us, enter our bodies, emanate from us,” Ackerman writes. “We live in a constant wash of them. Still when we try to describe a smell, words fail us like the fabrications they are.”

Ackerman puts forth the claim that while smell and long-term memory are strongly bonded, the connection between smell and the portion of our brain that forms words is much weaker, which makes describing smell, and thus the acceptance of perfumes, essential oil blends and handcrafted scents as an art form harder to swallow.

In his review of “Perfumes,” an exhaustive collective of perfume reviews, Rishidev Chaudhuri writes that the difficulty of describing smell is in part due to how we as a culture approach scents.

“Smell is almost always seen as a primitive, noble-savage sort of sense, pre-verbal and inextricably linked to sex and memory,” Chaudhuri writes.

He also questions whether the scarcity of words we have at our disposal to describe smell is the cause or the effect of the difficulty to describe the various odors we encounter.

“Smell frustrates in the paucity of the language we have attached to it,” Chaudhuri writes. “Perhaps this is a consequence of the way it intuitively seems primitive and direct and strongly evocative of the memory, or perhaps this is the cause … .”

incense sticks with essential oils

How Smell Affects Us

Smell plays a huge role in how we perceive the world around us. In fact, our sense of smell even determines 90 percent of how we perceive the taste of food. Taste, as it turns out, is an incredibly limited sense compared to smell. Our taste buds are capable of perceiving only sweet, sour, salty, bitter, richness and astringency. All the other subtle taste of foods we know so well comes from the nose, which explains why food turns so bland when we’re sick and congested.

In regard to how our mood is affected by smell, Rachel S. Herz, a psychology professor at Brown University, told the Scientific American that smell affects us through a sort of Pavlovian association.

“Odors do affect people’s mood, work performance and behavior in a variety of ways, but it isn’t because odors work on us like a drug, instead we work on them through our experiences with them,” Herz said. “That is, in order for an odor to elicit any sort of response in you, you have to first learn to associate it with some event.”

This doesn’t mean that crafted scents like essential oil blends, incense or candles are arbitrary or meaningless—quite the opposite actually! You might attach the smell of citrus, for example, to a long-past memory of a wonderfully relaxing tropical vacation with loved ones. Smelling citrus now subconsciously brings back those feelings of happiness and relaxation. Especially when choosing essential oils, recognizing how smells shape our thoughts and feelings can allow them to better aid us in our everyday lives.

Try shaping your environment yourself to test this theory. Why not try to re-create a re-create a spa experience at home or even make your own car air freshener using essential oils? Using essential oils to shape your mood is a great way to inspire your mind and awaken your senses in ways that may surprise you.


Hutton Marshall

Hutton Marshall is a freelance writer and photographer currently based in San Jose, Costa Rica. Contact him at jhuttonmarshall@gmail.com.