Smells can transport us back to powerful and emotional memories from the past more effectively as compared to sounds, a new study has found.
A well-known idea called the "Proustian phenomenon" proposes that distinctive smells have more power than any other sense to help us recall distant memories, the Telegraph reported.
The theory is named after the French writer Marcel Proust, who in his novel 'A la recherche du temps perdu' (In search of lost time) describes a character vividly recalling long-forgotten memories from his childhood after smelling a tea-soaked madeleine biscuit.
Experts have suggested that the special impact of odour on our memory could be related to the proximity of the closeness of our olfactory bulb, which helps us process smells, and the amygdala and hippocampus brain regions which control emotion and memory.
However, although the theory is well-known anecdotally, no studies have been able to firmly establish that the phenomenon even exists.
Now researchers could have gone a step closer to proving it after an experiment showed smells trigger more detailed, arousing and unpleasant memories of painful experiences than sounds.
A team from Utrecht University in The Netherlands recruited 70 female students and played them video footage designed to provoke aversion, such as car accidents and reports on the Rwandan genocide.
While the film was played, the smell of cassis was pumped into the room, coloured lights were directed onto the back wall and neutral music was played in the background.
A week later, the participants were asked to recall their memories of the film while exposed to either the same smell, lights or sounds used in the initial screening.
Those who were given the cassis smell remembered more details about the film and found their memories more unpleasant and arousing than those who had the background music as a memory trigger, although the lights and the smell were equally effective.
Researchers said that there was no difference between the triggers in two other categories measuring how evocative and vivid the memories were.
Re-testing participants after a longer period than one week could produce more distinctive results, they said.
The researchers said that the findings "do not confirm the Proust phenomenon", but could prove useful for research into post-traumatic stress disorder, which causes patients to recall vivid and painful experiences.
The study has been published in the Cognition and Emotion journal.