Although it is winter now, autumn is a season that brings with it numerous scents that are characteristic for that period of the year. For example, the smell of bonfire smoke, or perhaps the most recognizable smell of autumn air. But no matter what the smell is, it is known that it can, in some way return you to the past and bring you some memories.
So, certain scents can be a trigger for you to recall some of the events or memories that this smell reminds you on. But what is the cause of such a reaction of our brain?
Actually, it’s because of brain anatomy. The first thing that recognizes and treats the scent is the olfactory bulb, which is in the nose and which is associated with some parts of the brain. These parts of the brain are amygdala and hippocampus and they are linked to memory and emotions.
This connection with amygdala and hippocampus is crucial, because, for example, the information we receive through the eyesight, the sense of hearing or the sense of touch do not come into contact with them. And that’s the main reason, why the sense of the smell is stronger than any other sense in our body.
In one study, Herz and his colleagues at Brown University tested ten years ago the connection of smells with emotions and memory. Testing was performed with perfumes that reminded participants of the test of a particular memory they then described. After that the test was continued in the laboratory where they were subjected to the fMRI experiment.
The experiment meant that the participants were in the scanner, and that they were shown two images of perfume bottles during that time. The first was the image of the selected perfume (EV-the experimental visual), while the other was a picture of a perfume that did not contain any marks (CV-the control visual). It was a visual part of the test, while the olfactory part contained the fragrance of both perfumes (EO-the experimental odor and CO-the control odor). If the samples used in the test caused some kind of emotion or memory, the participants should have remembered it, in order to use it later in the test.
This test showed that increased activity was present in the amygdala and parahippocampal area when participants were exposed to the experimental odor. This means that there is a connection between memory and emotions and certain smells. Also, this test also showed a great power of smell. It should be noted that five women participated in the test. However, to be completely sure of the results of this test, it must include both men and women, in order to make the results valid.
There are some more tests and research that show a strong connection of scents with memories and emotions, and that the scents are more powerful than visual stimuli. After Herz’s research, some tests were performed that showed the relationship between smell and autobiographical memory.
The research conducted by Arshamian with the help of his colleagues showed a power of smell stimuli versus audio stimuli. For example, increased activity in the hippocampus and amygdala area were noticed at participants when they felt the smell of roses, more than when they heard the word “rose”.
In addition to the fact that different scents can refer to some positive memories or events, they can also remind us of some negative memories. For example, this is particularly pronounced in people with posttraumatic stress disorder. This was demonstrated by Vermetten and Bremner ten years ago in one their research.
On that occasion, one test participant had problems when he felt the smell of diesel. He would, whenever he felt the smell of diesel, feel guilt and helplessness, which was the consequence of the Vietnam war. He could not help his fellow soldiers to escape from burning vehicle, and that later caused posttraumatic stress disorder. That’s why the smell of diesel has always brought negative and traumatic memories back to him. This participant could see scenes from the war that remained forever in memory, even after more than 30 years.
Also, Herz and von Clef in one test showed that people respond differently to smells that are similar in chemical composition. For example, participants rated the sample marked positive (“parmesan cheese”) with the higher score rather than the identical sample that was marked negatively (“vomit”).
Although the smells are very powerful and they bring back different memories, we hope that they will remind you only of positive ones.
