The brain is constantly making decisions and filtering information. What gets into a person's long-term memory and what doesn't? "That's where smell comes in," says neurobiologist Jürgen Kornmeier from the Freiburg Institute for the Frontiers of Psychology and Mental Hygiene.
In a study whose results were published in the professional magazine "Nature", participants were given the task of learning Japanese words. They studied a total of 40 words for three days. All 165 subjects received a package of fragrances, only half of them actually had the fragrance inside, while others did not.
Those subjects who smelled roses while studying and also inhaled that scent at night had more success on the test - they knew more words. When the groups were compared, it turned out that the group that studied with the smell of roses was able to remember 8,5 percent more words.
Why does the brain remember better with smell?
"When we learn something, it's always about context," says Kornmeier. According to him, smells could play a certain role.
Words are associated with smell during learning. The brain remembers words better and remembers them better on the test. That is why the participants were allowed to smell the scent of the rose during the test. The brain quickly finds information that is associated with a smell, in this case a foreign word.
Smells particularly strongly activate the brain, this was shown by brain scans in earlier experiments. The hippocampus, which is the intermediary between short-term memory and long-term memory in the brain, is activated by smells. The theory says that the information obtained in this way is etched deeper into long-term memory.
Smell in sleep improves memory
And during sleep it is decided what the brain will remember. Earlier research in laboratory conditions showed that during deep sleep, the brain rearranges at least part of what is remembered and decides which information goes into long-term memory.
So with a smell, the content learned that day with the same smell should be reactivated when the brain recapitulates what was experienced and learned.
"Then the likelihood that they will take the learning content with them in the consolidation process increases," says Kornmeier.
The thesis of the scientist is - if the brain has already connected the information with the smell during the day, at night that smell alone can help to store it in long-term memory, the thesis states. Because the same nerve cells are activated that were already activated in the waking state during learning.
Possible daily use
Until now, other scientists have released the scent in their laboratories only during the deep sleep phase, so as not to disturb the other phases.
"But we can present the scent all night and it still works," says the neurobiologist. He adds that this is the first time that the fragrance has been used outside the laboratory, in home conditions. The participants of the Freiburg study studied at home, and not, as usual, in special rooms of the research team.
This means that application in everyday life is possible.
Scent to maximum effect
It is clear that the smell only supports the process. No one can renounce the effort of learning. But the smell helps with efficiency.
Kornmeier assumes that smell is effective above all when there is little time to study: "Smell could perhaps act as a kind of reinforcer." He believes that smells could help to reach one's own maximum in learning faster.
Smells do not seem to protect against forgetfulness. The positive effect of the smell was noticeable only in the first test, immediately after the learning phase. Already a week later, and especially after a month, it significantly weakened - the results of the group that used the rose scent were not significantly better than the results of the other group.
It's probably not just the scent of the rose that helps
Why the smell of roses? The largest number of studies used this very smell.
"It's a coincidence, that's how it was in the original research," says Kornmeier. All the studies that followed took the rose in order to be able to compare their results with that first study.
"But I firmly believe that other scents work as well. That has yet to be shown in future research."
The scent of lavender, orange, and many others could help with learning, at least in the short term. However, scientists are still in the process of understanding how the brain stores information and processes it at night. But one thing is for sure – smelling good could help you on your next test or exam.
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