A confession: I can tell my entire personal history through smells—baby powder and shampoo, my parents’ laundry detergent, the sea while growing up in Southeast Asia, tea tree oil I used to treat teenage acne, old books, lab chemicals, studio paints, and the many kitchens and apartments in the cities I have lived in. Smell can transport me to space and time, and thus, can serve as my olfactory timeline.

Helen Keller, who could neither see nor hear, used smell as a portal, too:

“Smell is a potent wizard that transports you across thousands of miles and all the years you have lived.”

Smell is our oldest sense and is the most powerful. About 2% of our genes are devoted to olfaction; other genes that can compare to this quantity are those for the immune system, which as we know are important for our survival. Hence, scientists believe that smell is more important than we think it is.

Smell is important for memory; this sense is processed in the brain’s limbic system where emotions are also processed. Hence, smell can be a very sentimental one. Impairment of smell has been found to be linked to Alzheimer’s disease, Parkinson’s disease, and aging. In literature, Proust’s encounter with the madeleine is often referenced, where eating the biscuit unleashed memories. A similar scene in Pixar’s 2007 film Ratatouille involves the food critic Anton Ego being transported to his childhood while eating Remy’s ratatouille. (Note that while these episodes involve eating, it is the smell that evokes emotion; consider pinching your nose while eating a meal. You will not be able to properly taste it.)

Anton Ego in Ratatouille (copyright Pixar 2007)

This obsession with smell led me to conduct a blind smell experiment using smells that were printed via microencapsulation.

I asked the participants to close their eyes and to do two things: 1) Describe the smell (and if they could, guess what they are smelling), and 2) Talk about a memory that comes to mind. Their eyes were closed so that they would not be influenced by what the label on the card said. Their responses, which were usually streams of consciousness, were recorded. When appropriate, I prompted them with additional questions, such as when the episode occurred, or if they were stumped with identifying it, to focus on describing the smell (e.g. sweet, sour, etc.) or mention metaphorical associations with it (e.g. smells like a flower, a dish, etc). In between sniffing the cards, they had the option of smelling a hot cup of coffee to clear their sinuses, or to pause for a bit to take some fresh air.

The results of this experiment were quite astonishing. Here are some highlights and what I’ve learned from them:

Fresh air – Unsurprisingly, smells of what we buy do linger in our olfactory consciousness. This participant was interesting in that he could associate the smell with a product, recall a specific episodic memory, and associate the smell with a color.

“It smells like that freshening block you hang in a toilet …  Not that it seems like an air freshener. I definitely get that synthetic quality to it. I thought of this house that I went to once. It was with an ex-girlfriend—I was maybe 16 or 17. It was with her and her mother and it was her friend’s house, which I’ve probably went to once in my life. It reminds me of color as well—a pale pink peach color.”

Eucalyptus  – Some smells could not trigger a specific episodic memory, but concrete associations.

“It smells like a woman, some florally perfume … I guess i could smell a grandma, not mine but what I imagine … like a fat grandma with big boobs.”

“I don’t know what it smells like. But if it had a sex, it would be male, not female because for me it’s strong and a little cold.”

Strawberry – Some memories were specific to a particular event or interaction.

“It reminds me of Strawberry Shortcake, the doll. When I was in fourth grade, I had a friend… he had a younger sister who had one. We were in the playroom … Yeah, smells like strawberry, smells like neapolitan ice cream.”

Tea tree – This was striking because the smell on the card was very faint, and the participant had a minor cold. This made me think that smell can indeed be trained; the participant grew up in India, perhaps similar to my experience growing up in tropical Manila where the smells are more potent.

“It smells like winter, not in a plant way, because I’m usually sick in winter. smells like the cold balm I would use … some sort of a minty, oily smell. It’s [the balm] is strong; despite having a cold, I can still smell it. It also reminds me of a really famous clothing store in India because it uses organic dyes. Eucalyptus, tea tree oil or mint smell to it.”

Burnt rubber – This was particularly interesting because of the divergent associations these two participants had. One had a traumatic incident involving this smell while the other did not and so picked up on the sweeter notes of the smell.

“Whoa. This reminds me of something. It reminds me of going to the dentist. The smell of rubber gloves maybe? Having a hand placed in my mouth. Getting braces … in the 6th-8th grade. Teeth started to hurt smelling this.”

“It reminds me of my grandfather’s old house they [grandparents] used to live in. It’s not a cooking smell, it’s not as fresh. It’s sort of a flowery smell close to parma violets. Lavender flower, I suppose. Maybe it’s something between flowers and sweets. It reminds me of a specific part of the house which is to the back of it … a cupboard that had sweet things and flowers. The memory made me smell the thing, but the smell itself didn’t remind me of these things.”

Update: The resulting project from this experiment is An Olfactory Memoir of Three Cities, a book of my smell memories.