A team of researchers has discovered that memories tend to be stronger when unpleasant odors accompany the original experiences. The new research strengthens the basic understanding of what can drive Pavlovian responses and points to how negative experiences influence a human's ability to recall past occurrences.
According to the assistant professor in New York University's Department of Psychology and the senior author of the paper, Catherine Hartley, these outcomes 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. The findings of the study appear in the journal Learning and Memory.
The lead author of the study and an NYU post-doctoral fellow, Alexandra Cohen, said that because their findings spanned different age groups, this research suggests that aversive odors might be used in the future to examine emotional learning and memory processes across development.
As it is familiar to us, the effect of negative experiences on memory has long been revealed. For instance, when a dog bites you, you may develop a negative memory of the dog that bit you, and your negative association may also go on to generalize to all dogs. Furthermore, due to the trauma surrounding the bite, you are likely to have a better recollection of it than you would other past experiences with dogs.
According to Hartley, the generalization and persistence in memory of learned negative associations are the core features of anxiety disorders, which often emerge during adolescence.
For the researchers to understand better how learned negative associations influence memory during this stage of development, the team 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 survey, the scientists used bad smells because they can be ethically administered in studying children.
Included in the task was the viewing of a series of images belonging to one of two conceptual categories; objects like a chair, and scenes such as a snow-capped mountain. As the participants of the study viewed the images, they wore a nasal mask connected to an olfactometer. When participants viewed images from one category, unpleasant smells were sometimes circulated through the device to the mask, while viewing images from the other category, unscented air was used. This method allowed the researchers to examine memory for images associated with a bad smell as well as for generalization to related images. In other words, if the image of a chair was associated with a bad smell, would memory be enhanced only for the chair or for objects in general?
The findings of the surveys revealed that both adolescents and adults showed better memory specifically for images paired with the bad smell 24 hours after they saw these images. The investigator discovered that people 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 delivered, had better memory 24 hours later. This suggests that unpredictability or surprise associated with the result leads to better memory.
