Why Do Smells Trigger Memories?
What is it about our sense of smell that works to better trigger our memory and our emotions?
Whenever I smell the pages of a brand new book, I am reminded of all the late night reading I did as a kid. I can even feel the soft fabric on the arms of my favorite reading chair and sense the quiet of a house where everyone else is asleep. The stresses of the day start to give way a bit to feelings of calm and focus. We have an armchair in my daughter’s room very similar to my childhood reading chair, but sitting in it doesn’t quite conjure up those memories as effectively as that new book smell.
And I am not alone! Anecdotally, many of us have had experiences where a certain smell—perhaps chlorine, fresh baked cookies, or the salty beach air—floods our brain with memories of a distinct event or location that we associate clearly with certain emotions.
There have also been scientific studies using a variety of approaches to back up this anecdotal evidence. One of the first was a study led by Dr. Rachel Herz at Brown University in 2004. Herz and her collaborators found that a group of five women showed more brain activity when smelling a perfume with which they associated a positive memory than when smelling a control perfume they had never before smelled. The brain activity associated with the memorable perfume was also greater than that produced by the visual cue of seeing the bottle of perfume.
More recently, in another study in 2013, the researchers again found greater brain activity associated with olfactory stimuli (like the smell of a rose) than with visual stimuli (like the sight of a rose). Clinical case studies have also linked smells to strong negative emotions, a connection which can play a significant role in contributing to posttraumatic stress disorder.
So why is this? The majority of us clearly rely more on a sense of sight than our sense of smell day to day, so what is it about our sense of smell that works to better trigger our memory and our emotions? The link may simply be due to the architectural layout of our brain.
How does our sense of smell work?
The process through which molecules in the air are converted by our brain into what we interpret as smells and the mechanisms our brain uses to categorize and interpret those odors is, as you have probably guessed, a complicated one. In fact, the process is so complicated that the Nobel Prize in Physiology or Medicine was awarded in 2004 to the researchers Richard Axel and Linda Buck for their work in decoding it.