If it seems that you recall particular scents from childhood more vividly than other (more recent) smells, there may be a bona fide biological reason. New research suggests that these “first scents” occupy a privileged place in the brain.
For the study, appearing online in Current Biology, researchers at the Weizmann Institute of Science in Israel positioned volunteers in a functional magnetic resonance imaging (fMRI) machine and presented them with a visual image along with a combination of pleasant and unpleasant smells and sounds. They did this twice, 90 minutes apart. Then, a week later, the scientists put their subjects back in the fMRI machine and presented the same visual image combined with the combination of odors and noises. The goal was to test the subjects’ associations with the images and the smells.
The researchers found that the study participants remembered early associations more clearly when they were unpleasant, regardless of whether they were smelled or heard. The authors point out that from an evolutionary standpoint it makes sense that the brain prioritizes unpleasant memories over pleasant ones. But they also noted that early smell memories are special.
“We found that the first pairing or association between an object and a smell had a distinct signature in the brain,” even in adults, says Yaara Yeshurun, a neurobiologist and the study’s lead author.