Smell and MemoryThe Power of Scent: Understanding the Strong Connection Between Smells and Memories

The Power of Scent: Understanding the Strong Connection Between Smells and Memories

Whenever I smell mothballs, I go back in time. Suddenly, I’m back in my grandparents’ cabin in Maine, where I spent many summers growing up—and where the distinct, musty smell of mothballs wafted from the hall closet. If I catch even a whiff today, I’m instantly drawn back into that hallway, filled with a deep sense of comfort and security.

It seems a given that the sense of smell is closely related to memory. (Right now, you may be recalling your own odor-triggered memories.) In fact, lots of research have discovered a connection between smells, emotions and powerful memories. Neuroscientists have even used fMRI brain scan to show that smells evoke strong memories and emotions due to the brain areas responsible for processing them.

In short, the nose knows more than we think. Here’s what researchers have discovered about how smell, memory and emotion are intertwined.

Which parts of the brain control smell?

Scientists and scientists are discovering the connection between smell and emotional memory for well over a century. And while this connection is becoming better understood, our understanding of it is still quite primitive, says Venkatesh Murthy, a neuroscientist at Harvard University whose lab studies the neural basis of odor-guided behavior in animals.

Read more: Why some people love the smell of gasoline

However, the architecture of the brain itself may offer some clues. Odors are processed by olfactory bulb, a structure located in the front of the brain before being sent on a direct route to the limbic system—which includes the amygdala and hippocampus, the regions that regulate emotion and memory. These privileged connections between the olfactory system and the limbic system may help explain why smell, in particular, can trigger stronger emotional memories than our other senses.

“When we think about [the regions responsible for processing] memory and emotion, they just happen to be physically or geographically close to the parts of the brain involved in olfaction,” Murthy says. “One attractive idea is that perhaps it is the proximity of these connections; it takes fewer stations to reach directly [from smell to emotion and memory.]”

Emerging research seems to support this as well. The scientists used neuroimaging and intracranial electrophysiology – where electrodes are placed directly on the brain of an exposed participant to record their electrical activity – to show that the relationship between hippocampus and olfactory system is stronger than our other sensory systems, according to a study published in Advances in Neurobiology in 2021

What types of memory involve olfaction?

Not all types of memory are the same. Working memoryor short-term memory, refers to our ability to hold small pieces of current information in our minds—for example, when you think of a phone number while adding it to your contact list. Semantic memoryon the other hand, it refers to our general knowledge of the world, such as facts and abstract concepts.

But it is episodic memory, or memories of specific first-person events that are most closely related to our sense of smell. In other words, memories evoked by smells are usually autobiographical and deeply connected to the person experiencing them.

“Much of the power of smells to evoke certain memories comes from a particular life experience that an individual has had,” says Teresa L. White, a professor of psychology at Le Moyne College who studies learning, memory and sensory psychology. “Doing research with smells is so variable because people have had different experiences.”

How does taste affect smell?

What’s more, these memories can also include things we tend to associate with our sense of taste. (Try pinching your nose the next time you sink your teeth into a particularly tasty meal.) French writer Marcel Proust’s literary musings on memory were known trigger not from a specific smell, but from eating a Madeleine cake and a sip of tea.

“Instead of thinking about pure smells, if you think about foods, you know that people have very different tastes,” says White. “A lot of what comes from taste is smell.”

Read more: Why does our sense of taste change as we age?

Murthy agrees, noting that what we think of as “taste” or aroma is a combination of our senses of taste and smell. This is because when we bite into something, the molecules from the food we eat are broken down and sent to nasal epithelium and olfactory bulb for processing.

“When you eat, a lot of the sensation you get is actually smell, because chewing evaporates this stuff and it goes to the back of your mouth and eventually your nose,” Murthy adds.

Why does smell trigger memory?

Let’s summarize: A growing body of research has discovered connections between smells and strong, emotionally charged memories. Scientists believe that memory and smell may be more closely linked than the other senses because the structure of the brain allows rapid connections between the olfactory system and the limbic system, where emotions and memory are processed.

What’s more, researchers believe that odor-triggered memories tend to be associated with unusual scents or scents from long ago that we don’t think about often—like, in my case, the musky scent of mothballs. When this happens, it can feel like we’re re-experiencing those emotions for the first time.

“When we notice something that we haven’t smelled in a particularly long time, it can bring us back to that episodic memory and connect us to it,” says White.

For White, the smell of gardenias takes her back to childhood, when she had gardenia bushes outside her house and her aunt’s house as a little girl.

“I remember being there with my aunt cutting them, and literally smelling them until they were brown,” she says. “It takes you back to that time and something early in life.”

“I think that’s one of the reasons why smells stand out to people,” adds White. “The memories they reveal are not ones we think about very often. Most people are surprised to get back into it.”

Read more: What happens in your brain when you make memories?

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