Science Explains Why Smell Is The Strongest Trigger Of Emotional Memories

Ever randomly caught a whiff of perfume when walking around town and suddenly felt transported to a moment in your childhood? Maybe when you were first introduced to your favorite aunt or even to the teacher you hated the most as a kid?

Even the Director of the Laboratory of Cognitive Neurobiology at Boston University, Howard Eichenbaum, explains how the perfume of a random lady in an elevator transported him back to a memory in high school.


Anthropologically, our sense of smell is said to go back to our prehistoric ancestors who used it as a tool to avoid poisonous plants or sense danger from the smell of a wild animal, which is also something that helps us modern folk be able to tell if food has gone bad or if there is a gas leak, as some common examples.

However, it also plays a key role in memory recreation, almost as if we are literally re-experiencing something from our pasts. Although science has preached that smell is one of the strongest evokers of the past, new research studies have shown that scents from the past, stay in the dormant parts of our long-term memory, till they are triggered.


Our Aromatically Emotional Brain


Our other senses all play a role in triggering memories, but for some reason, smell is one of the stronger senses in sparking a flood of emotions attached to those memories.1


Here’s How It Happens:

-Once a smell enters our noses, it travels through the cranial nerve (one of the 12 important paired nerves in the brain), passes through the olfactory bulb (the area which helps us process and differentiate between various smells).


-The olfactory bulb also happens to be one of the many parts of the limbic system (nerve structures responsible for processing emotional behavior or responses). So being a  fellow worker in the limbic system, the olfactory bulb can easily connect with another member, i.e. the amygdala (the core nerve structure behind emotions, motivation, the ‘fight or flight’ reflex; who also works closely with the hippocampus a.k.a the memory creating and storing center).

-The olfactory bulb’s strong influence on the amygdala (including it’s own connection to the memory area of the brain), are what all swiftly merge together and turn that simple smell into an emotionally-tugging memory.


Essentially, our nostalgic sensations from smell may be the lovechild of the olfactory bulb and the amygdala.

According to Dr. Ron DeVere, the Director of a Taste and Smell Disorders Clinic in Austin, Texas, we actually do not make use of our emotional memory that much, because when we try to remember something consciously, we look at them as visual details NOT as feelings. Likewise, just as how smell is chummy with the emotional and memory parts of the brain, words are processed by the cerebrum (the biggest part of the brain which is responsible for thinking and your voluntary muscles).


This is why smell makes you feel emotional and nostalgic of a memory in a more vivid sense with less details, as opposed to ones processed by the thinking sector of your brain which are packed with tiny details.

In addition, when the smell of chocolate cake from your neighborhood bakery reminds you of your first visit to your grandmother’s house, it’s not a conscious identification, but an involuntary reflex, because you stored that smell as an association to that experience or memory.



The Odorous Experiments

Dr. Yaara Yeshurun, the researcher behind a study conducted at the Weizmann Institute of Science in Israel, explained that these smell-borne memories hold a VIP-like status in our memory bank. Yes!

Combing the results of earlier studies, those smell triggered memories are said to rank above memories associated with pictures, words, and even sounds, within our brains.

Who knew our brains had a class-system for memories!

Published in the Journal of Current Biology, the study involved 16 volunteers who were where asked to sniff mimicked smells that were responsible for creating their childhood memories.

The tests were conducted as the participants were inside a functional Magnetic Resonance Imaging (fMRI) scanner, a machine which supervises brain activity.

First, the participants were shown the image of an object while they had to sniff the scent of a pear or fungus at the same time.

Around 90 minutes later, they were shown the same image but were made to sniff a different smell.

When looking at their MRI scans, the hippocampus region of the brain ‘sparked’ vibrantly at the moment the participants were exposed to their first smell.

But their brains did not respond in the same way when the volunteers sniffed the second smell.

Giving the gap of around 7 days later, the participants were called back by the scientists. Upon exposing the participants to the first smell, the scientists noted how strongly they associated that smell to the image they saw.

Moreover, the hippocampus region of their brain lit up in a similar manner, as it did before, when they were trying to recall that first smell from a week earlier.

To take this study a step further, the experiment was conducted again by using sound instead of smell, to know if sound has a similar impact as smell on memory.

But what they found was that those odor based memories had unique ‘signature’ traits which were totally different from other kinds of  memories.

The brains form something called “odor memories”, just like earlier mentioned association of a perfume to a person, which counts for both good and bad smell memories. More importantly, these first impression memories of a smell cannot be rewritten by any secondary association to that smell. 2

Which is probably the reason why you may hate the smell of any chemical mouthwash as it reminds you of your first ever visit to the dentist. No future memory after that can replace that deeply etched odor memory into your mind.

On the whole, the participants strong recall of unpleasant smells over pleasant ones, showed that we also remember bad memories better than good ones, especially the very first experiences which become a memory and those formed in the earliest stages of our lives.

This may be our noses way of sniffing out past experiences, which we thought we lost forever, even if we REALLY don’t want to remember them as much.