Monday, 23 January 2012

Do smells really trigger particularly evocative memories?

We wore ankle-length blue coats at my school, in the Tudor-style. When it rained, the wool of the coat gave off a pungent smell, rather like wet dog. Now when I encounter a similar scent, it propels me back in time to my school days. This effect is called the "Proustian phenomenon". The name comes from Proust's description in Remembrance of Things Past of how the smell of a tea-soaked madeleine biscuit transported him back in time to his childhood.

Smells do have this uncanny, evocative power, don't they? It's because of the relative proximity of the olfactory bulb (which processes smells) and the hippocampus and amygdala, which are involved in memory and emotions. Right?

Not so fast. In fact very little research has investigated whether smells really do evoke vivid and emotional memories, more than other sensory cues. What follows is a new, rare attempt.

Marieke Toffolo and her collaborators invited 70 female student participants to watch a disturbing 12-minute film featuring road traffic accidents, surgery and reports on the Rwandan genocide. Whilst the students watched the film, the smell of Cassis, a neutral berry-like odour, was sprayed into the room; coloured lights were projected onto the back wall; and inoffensive background music was played over speakers (no mention was made to the students of these cues; pilot work established that they were equally noticeable, pleasant and arousing). The researchers chose to focus only on female participants to keep things simple, because it's known that there are sex differences in olfactory perception.

A week later the students were called back and asked to write down as many memories about the film as they could. As they did so, either the smell, the lights or the music were presented again. The students also answered questions about the quality of their memories. The main finding is that students exposed again to the smell of Cassis rated their memories of the film as more detailed, unpleasant and arousing (but no more transporting or vivid) than students re-exposed to the music. However, the students re-exposed to the odour rated their memories no differently from students re-exposed to the lights. In other words, smell appeared to be more evocative than music, but no more evocative than lights.

"It could be argued that a necessary implication of the Proust phenomenon is that odours are more effective triggers of emotional memories than other-modality triggers," the researchers said. "Under such strong assumptions the results reported here do not confirm the Proust phenomenon. Nonetheless, our findings do extend previous research by demonstrating that odour is a stronger trigger of detailed and arousing memories than music, which has often been held to provide equally powerful triggers as odours."

Toffolo, M., Smeets, M., and van den Hout, M. (2012). Proust revisited: Odours as triggers of aversive memories. Cognition and Emotion, 26 (1), 83-92 DOI: 10.1080/02699931.2011.555475

Post written by Christian Jarrett for the BPS Research Digest.


Gordon Ingram said...

Yes, but the phenomenologically interesting thing about olfactory memory is the way it can transport you back over many years - as in Proust's and your own example. Testing people after one week just doesn't cut it, although I suppose it does provide a good baseline for the follow-up study. I look forward to seeing the real results in five or ten years' time!
(Another interesting thing to test would be tactile memory: a few months ago I revisited the street where I grew up, for the first time in many years. I was surprised - and a little frustrated - by how visually unfamiliar it seemed. Yet when I ran my hand along the stone wall of the church at the bottom of the street, a wall that I had touched many times as a child, it felt exactly the same and it was as though I was standing there as a child once again.)

Unknown said...

Hi Gordon - you're absolutely right. The timescale is a major weakness of the study and in fairness the authors do acknowledge that problem in their discussion. Also really interesting to hear about that tactile memory experience you had. I wonder if the point about Proustian memories isn't to do with one sensory modality more than another, but something to do with the uniqueness of the original sensory experience. If you've never felt a wall like that since your childhood, perhaps it makes sense that feeling it again transported you back in time?

netmarcos said...

A casual whiff of fresh white glue always takes me back to the summer of 1975. I imagine a play list of songs, the dim lights of the lower level of our home and the complicated balsa and tissue-paper bi-plane that I built that summer and flew in the park across the street from our home. The music doesn't do it, the lighting doesn't do it. Looking at pictures of the house and the park don't immediately bring to mind the same memories, but the smell of Elmer's glue always does.

Jonathan Bollag said...

I think it would have been interesting if they did a seperate study using male participants. I understand their write off of using both genders mixed in one experiment, but it would be interesting to see if males had a similar preference or different vs other males.

Anonymous said...

From a personal POV music can definitely transport me back, particularly if it's a song I haven't listened to for a number of years but listened to a lot over a certain period of my life.

The example with the wall is also interesting. I don't think I've ever experienced anything like that.

Megan Kerr said...

I think that uniqueness of the sensory experience is key - you can choose to listen to a song again, and gradually rid it of its associations, but it's hard to access the exact same smell. Also, the memories that people are talking about when they talk about smell are much richer, more personal, and longer-lasting, than what happened in a film. Smell seems to take one back to an era, rather than to one specific event.

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