Why Do Smells Trigger Specific Memories?

You're waiting in the never-ending line to pay at the cash counter at the grocery store when a batch of freshly baked croissants make their way to the nearby patisserie. The smell of butter, sugar and dough enter through your nose and evoke a powerful memory from your childhood—a baking competition in junior school, where your parents tried their hand at homemade croissants; the last time they laughed together. A profound sense of despair and anguish dawns upon you but vanishes as quickly as it came.

Let us guess your next thought: "what in the world was that?"

Here's what it was: Scent, memory, and emotion are intertwined. Odours often evoke vivid memories, taking a direct route to the limbic system, including the amygdala and the hippocampus. Dr Vinit Suri, Senior Consultant, Neurology, Indraprastha Apollo Hospitals, explains "Our memory is controlled by the limbic system of the brain and all sensations—visual, auditory, gustatory, tactile, and olfactory—are stored in the association areas. Hence, whenever an event is in reference to the memories of the association area, one gets reminded of an experience that took place previously."

Psychologist and M.Phil Scholar, Sanjoni Sethi adds, "When an odour occurs, emotional experience and meaning may be associated with the scent. This form of association comes from learning principles. Thus, a specific odour related to an individual’s experience becomes part of the autobiographical memory schemas. Smell elicited memories are known to uplift moods when compared to memories evoked by another sensory modality. Aromas that trigger specific personal memory such as nostalgic memory arouse feelings of happiness, optimism, and joy. On the other hand, researchers have found that negative emotions are particularly associated with the smell of a specific material—such as diesel or petrol—for individuals who have undergone traumatic events related to such materials (for instance, a car accident). 

Although, scent memories are often found to be more powerful as compared to those triggered by our other senses. Why? "The olfactory bulb has a direct connection with the limbic system, making smell an important sensory modality that can be instantly linked to previous memories. Plus, the limbic system contains information related to moods as well," informs Dr Suri.

In simpler terms, scientists believe that the brain regions accountable for the processes of memory, emotion, and smell functions (commonly known as olfactory sense) work hand-in-hand. The three brain regions are responsible for associating a smell with certain emotions and bringing back a particular memory, as the process is intertwined. A recent study published in Progress in Neurobiology explores the power of scent in triggering memories, indicating that this ability comes from the connection between the olfactory system and the hippocampus in the brain.