Because the part of the brain that processes smells and the cerebral area involved in memory and emotions are relatively close together, scientists long assumed that aromas have a stronger evocative power than visual or other sensory input. But new research may prove them wrong.

Marieke Toffolo and her collaborators at Utrecht University in the Netherlands had 70 female volunteers watch a disturbing 12-minute film featuring car accidents, surgery, and reports on the Rwandan genocide. During the viewing, the smell of Cassis, a neutral berry-like odor, was sprayed into the room, coloured lights were projected onto the back wall, and inoffensive music was played.

A week later, the participants returned. Then, while either the smell, the lights or the music were presented again, they wrote down as many memories about the film as they could, and also answered questions about the quality of their memories.

The results showed the volunteers re-exposed to the smell of Cassis rated their memories of the film as more detailed, unpleasant and arousing — but no more transporting or vivid — than the people re-exposed to the music. However, the participants re-exposed to the odor rated their memories no differently that those re-exposed to the lights.

In other words, while smell appeared to be more evocative than music, it wasn’t any more evocative than lights.

“The present study demonstrated that aversive memories evoked by olfactory triggers were more detailed, arousing and unpleasant than memories evoked by auditory triggers,” the researchers wrote in Cognition and Emotion. “However, odors were not more evocative or emotive than visual triggers.”

The authors also noted that because their study only involved female volunteers, the results may not apply to everyone. But since more women than men suffer from PTSD, the new findings could be particularly meaningful for women.