Israeli Scientists Take a Whiff of our Brains
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Why is it that mom’s laundry always smells better? What is it in perfume that reminds us of a pleasant, distant memory? These are just some of the questions scientists at the Weizmann Institute’s “smell lab” in Israel are trying to figure out.
Throughout the years, everyone from artists to psychologists have tried to figure out the associations certain smells create in our minds. And until now, the most common answer to this phenomenon relates to the introductory event we have with that smell.
If, for instance, my girlfriend wore ginger-scented perfume when we met, I would likely associate the smell to that romantic evening three years ago. Meanwhile, another person may relate the smell of ginger to a horrible dish her mother used to make.
While this answer would suffice for most of us, researchers Yaara Yeshuroun and Prof. Noam Sobel believe there is more to be uncovered. In order to see if our common sense actually fits a scientific explanation, Ms. Yeshouroun hooked up a group of test subjects to an fMRI machine and started recording their brain waves, as they were presented with a variety of smells both pleasant and unpleasant. To make it even more complicated, each smell was matched with either a pleasant or unpleasant picture.
After doing this a number of times, the test group was sent home, only to be called back again for a questioning on the memories they had from the previous session. In that session, the scientists found that after one week, even if the subject recalled both odors equally, the first association revealed a distinctive pattern of brain activity. The effect was seen whether the smell was pleasant or unpleasant.
The pattern was so profound, it enabled the scientists to predict which associations would be remembered just by looking at the brain activity within these regions following the initial exposure. The scientists could look at the fMRI data on the first day of the experiment and predict which associations would come up a week later.
To see if other sensory experiences might share this tendency, the scientists repeated the entire experiment using sounds rather than smells. They found that sounds did not arouse a similar distinctive first-time pattern of activity. In other words, these results were specific to the sense of smell.
“For some reason, the first association with smell gets etched into memory,” says Prof. Sobel, “and this phenomenon allowed us to predict what would be remembered one week later based on brain activity alone.”
Although this prediction gives a somewhat cold and objective account to a phenomena we usually prefer more obscure, Yarra Yeshuroun argues that it doesn’t take away from the magic: “Childhood olfactory memories may be special not because childhood is special, but simply because those years may be the first time we associate something with an odor,” she says. “But since it is our first exposure to those smells, for us it will always remain unique.”
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