A familiar smell can suddenly bring a childhood scene vividly to mind. One study compared this experience with looking at a photograph of the same object.
In an experiment involving 170 students, people who smelled Vicks VapoRub, selected for its association with childhood, rated their memories as more vivid than those who saw its image. The same difference was not found for vinegar. The results suggest that connections with memories matter, rather than every odor working in the same way.
- How can richer memories be compared?
- Selecting an odor associated with childhood in advance
- One hundred seventy participants revisited memories chosen from names
- Higher ratings for the smell of VapoRub
- The clearest difference was in vividness
- No difference in emotion words in written memories
- Cues to nostalgia depend on experience
- Summary
How can richer memories be compared?
The study concerned memories of personally experienced past events, known as autobiographical memories. Unlike experiments in memorizing words, it dealt with memories formed in everyday life.
Comparisons in odor-and-memory research are difficult. If people smelling an odor and people viewing a picture recall different events from the outset, any difference could reflect the original memories rather than the cues. The effects of smelling an odor can also overlap with recognizing the product.
The team therefore first presented an object’s name and asked participants to choose a memory, then presented either its odor or image. This double-cueing procedure added a sensory cue after an initial verbal cue. It allowed the researchers to examine whether odors enhanced the subjective richness of memories more than images did.
Selecting an odor associated with childhood in advance
A pilot study presented ten odors to 17 students and staff at a Dutch university. For stimuli including peanut butter, baby powder, cinnamon, coffee, and sunscreen, participants were asked whether they could identify the odor and how strongly they associated it with childhood.
Vicks VapoRub was readily recognized and strongly associated with childhood, so it was selected as the childhood-related stimulus. Vinegar was relatively recognizable but had a weaker childhood association, making it a contrasting stimulus.
Childhood-related here describes the odor’s position within this pilot sample. It is not a universal property extending to people who have never used the product; it depends on what was familiar while growing up.
One hundred seventy participants revisited memories chosen from names
The main experiment involved 170 psychology students at a Dutch university. Their mean age was 20, and the sample included more women than men. Everyone first recalled and briefly wrote down a childhood memory for each of VapoRub and vinegar.
They were then randomly assigned either to smell the actual substances or to view images of the products. Odors were presented in opaque metal containers labeled to identify their contents. The images also showed readable product names and appeared on screen for ten seconds.
Each participant experienced both VapoRub and vinegar, with presentation order counterbalanced. After each presentation, they described the initially selected memory in as much detail as possible and rated its vividness, detail, and emotional intensity.
Half the sample, 85 people, also rated the same three items before the sensory cue. The paper’s no-cue condition refers to this pre-cue assessment, not to a separate control group of 85 people who received no stimulus.
Higher ratings for the smell of VapoRub
The main analysis averaged vividness, detail, and emotional intensity into a composite score of subjective memory quality. Among participants who also rated their memories before cue presentation, composite scores rose after sensory cues for both VapoRub and vinegar. This comparison included both odor and image conditions.
In the study’s central direct comparison of odors and images, the VapoRub composite score was 4.09 in the odor condition and 3.57 in the image condition, a significant advantage for odor (p = 0.04). Vinegar showed no significant difference between odor and image cues.
Thus, even after participants knew the object’s name and had already selected an event to recall, adding VapoRub’s actual odor enhanced their ratings of the memory experience.
The clearest difference was in vividness
Examining the three items separately makes the results more specific. VapoRub vividness ratings were 4.58 with odor and 3.85 with an image, a significant difference (p = 0.01).
Although mean ratings of detail and emotional intensity were higher with odor, their differences from the image condition were not significant (p = 0.18 and p = 0.17, respectively). Rather than treating the higher composite score as evidence that every detail and emotion became stronger, recognizing vividness as the clearest finding preserves the meaning of the results.
For vinegar, none of these individual measures differed significantly between odor and image conditions. This comparison of two stimuli supports the possibility that childhood-associated odors can act as cues that make memories from that period feel more vivid.
No difference in emotion words in written memories
The team also examined the language used in participants’ memory descriptions. Using the Dutch version of the LIWC text-analysis tool, they compared the proportions of words relating to overall emotion, positive emotion, and negative emotion.
Neither VapoRub nor vinegar showed significant differences between odor and image conditions. Ratings of how a memory feels and the proportion of emotional words in a written account are different measures.
The authors discuss how recalling a vivid memory does not necessarily mean that every aspect of the experience appears in writing. Including the null text-analysis findings helps clarify that the study primarily captured a change in subjective memory experience.
Cues to nostalgia depend on experience
Because everyone was asked to choose childhood memories, the study did not test whether odors retrieve older memories than pictures. Nor did it check how accurately recollections matched the actual events. Feeling that a memory is vivid must be distinguished from remembering accurately.
Only two stimuli were used, and VapoRub and vinegar differ in ways other than their childhood associations. The researchers did not choose an individually optimal nostalgic odor for each participant, nor directly measure how important each memory was to that person. Selecting stimuli for different cultures, generations, and individual experiences is a task for future research.
Furthermore, the procedure began with deliberate recall prompted by a name, so it did not directly reproduce the experience of a street-corner smell suddenly bringing back a forgotten memory. Instead, fixing the memory first made it easier to compare what adding an odor changed.
Summary
For VapoRub, selected for its childhood associations, adding an odor to a memory chosen from its name produced higher composite and vividness ratings than viewing an image. Vinegar did not show the same significant differences, and neither separate ratings of detail and emotional intensity nor emotion words in written accounts showed clear odor-versus-image differences.
By deciding which event to recall before making the comparison, the study captured what odor adds to the experience of remembering. Not only the identity of a fragrance, but the experiences accumulated with it, may matter for its ability to make memories vivid.
The authors reported no potential conflicts of interest requiring disclosure.
References
de Bruijn MJ, Bender M. (2017 online). Olfactory cues are more effective than visual cues in experimentally triggering autobiographical memories. Memory. Original paper.
