There is a reason perfumes are usually expensive. Aside from having a beautiful fragrance, they also get etched in your memories. Even recent studies back this up. According to recent findings, memories are stronger when the original experiences are accompanied by unpleasant odours. The study broadens our understanding of what can drive Pavlovian responses and points to how negative experiences influence our ability to recall past events.
"These results demonstrate that bad smells are capable of producing memory enhancements in both adolescents and adults, pointing to new ways to study how we learn from and remember positive and negative experiences," explained Catherine Hartley, assistant professor in New York University's Department of Psychology.
"The generalization and persistence in memory of learned negative associations are core features of anxiety disorders, which often emerge during adolescence," Hartley noted. In order to better understand how learned negative associations influence memory during this stage of development, the researchers designed and administered a Pavlovian learning task to individuals aged 13 to 25. Mild electrical shocks are often used in this type of learning task. In this study, the researchers used bad smells because they can be ethically administered in studying children.
What constitutes a "bad" odor is somewhat subjective. In order to determine which odors the participants found unlikable, the researchers had the subjects--prior to the start of the experiment--breathe in a variety of odors and indicate which ones they thought were unpleasant. The odors were blends of chemical compounds provided by a local perfumer and included scents such as rotting fish and manure. As the subjects viewed the images, the scientists measured perspiration from the palm of the subjects' hands as an index of arousal--a common research technique used to confirm the creation of a negative association (in this case, of a bad smell). A day later, researchers tested participants' memory for the images.
Their findings showed that both adolescents and adults showed better memory specifically for images paired with the bad smell 24 hours after they saw these images. The researchers also found that individuals with larger arousal responses at the point when they might experience either a bad smell or clean air while viewing the image, regardless of whether or not smell was actually delivered, had better memory 24 hours later. This suggests that unpredictability or surprise associated with the outcome leads to better memory.