When people describe a perfume as energizing or relaxing, they link a scent with a mood in words. Could that connection be captured without directly asking for their impressions?
A study published by Cereghetti and colleagues in 2024 measured how quickly people responded to mood-related words after smelling an odour. The researchers developed an olfactory priming task, or OPT, to evaluate a method for measuring associations between odours and emotional words.
What asking how it feels may miss
Self-ratings of fragrance impressions are useful, but can be influenced by how easy an impression is to put into words or how people want to appear to others. The team therefore devised a task that did not require participants to directly report their impression of the odour.
The approach tests whether a preceding odour facilitates processing a subsequent word. If one odour helps people classify energizing-related words more quickly and another helps them classify calming-related words, this may reveal connections between the odours and those meanings.
Traditional association tasks sometimes compare combinations of two odours and two meanings together, making it difficult to separate which odour drives the result. OPT was designed to examine, for each individual odour, which category of words elicited faster responses.
First single odorants, then finished perfumes
The first experiment used menthol and vanillin. The second used two finished perfumes containing multiple ingredients to see whether the method also worked with more complex scents.
The perfume brands were not disclosed. Perfume 1 was described as citrus-aromatic, including bergamot and lemon, with floral notes layered with elements such as cedar and sandalwood.
Perfume 2 was described in the paper as oriental-floral, with elements including hawthorn, blackcurrant, violet, jasmine, vanilla, opoponax and white musk. These are descriptions of the scent composition, not formulas disclosing ingredient quantities.
Previous research had associated Perfume 1 with energizing feelings and Perfume 2 with relaxation. Rather than randomly selecting perfumes with subtle differences, the researchers first tested the new method using clearly differentiated stimuli.
Classifying two words after each odour
Each experiment recruited 46 employees, temporary employees, trainees and others at fragrance company DSM-Firmenich. Two people per experiment were excluded for technical reasons, leaving 44 in each analysis. In the perfume experiment, one further participant with extremely slow responses was excluded from reaction-time analysis only, leaving 43.
Participants first rated odour intensity, liking, familiarity and the extent of energizing or relaxing feelings. They then performed the word-classification task. Odours were delivered to the nose by an apparatus, not applied to the skin.
The targets were four French words related to relaxation and four related to energizing feelings. Participants saw a word on screen and pressed a key to identify its category as quickly and accurately as possible. They were instructed to ignore the odour.
Two words appeared in sequence after each odour delivery. The test phase comprised 96 classifications; the task took about 15 minutes. The design also aimed to provide a short measurement while limiting repeated odour delivery that could lead to habituation.
The first word showed a congruent response advantage
Responses were faster to energizing-related words after menthol and to relaxing-related words after vanillin. Finished perfumes produced results in the same direction.
After the citrus Perfume 1, mean reaction time to the first energizing-related word was 808 milliseconds, versus 844 milliseconds for relaxing-related words. After Perfume 2, the corresponding means were 797 milliseconds for relaxing-related words and 829 milliseconds for energizing-related words. These differences of roughly 0.03–0.04 seconds were small but statistically significant.
However, this pairing effect was not found for the second word following an odour. Neither experiment confirmed that odour-congruent words were classified more accurately.
Initial self-ratings also associated menthol and Perfume 1 more strongly with energizing feelings, and vanillin and Perfume 2 with relaxation. Indeed, the paper reports larger effects in self-ratings than in reaction times. The results do not show that OPT outperformed direct reports in every respect.
Why might responses become faster?
The authors suggested that an odour might activate emotional memories linked to past experience or representations of the corresponding feeling, facilitating the processing of related words. This draws on the idea that associations between odours and moods are learned through experience.
However, the faster responses cannot all be assumed to be unconscious. Approximately 3 seconds elapsed between the inhalation cue and the first word, allowing participants time to recognize the odour and anticipate what kind of word might follow. The authors acknowledged that the design did not separate automatic associations from conscious expectations.
Possible explanations for the absent second-word effect included the influence of the odour fading over time and the variable interval caused by different response times to the first word. The authors suggested that future versions might omit the second word.
A tool for measuring impressions, not perfume benefits
The study measured word-classification speed and self-ratings of odours. It did not use heart rate or similar measures to establish physiological calming or arousal, nor did it measure work efficiency or sustained mood change. It also cannot establish a general cognitive improvement relative to an odourless condition.
The authors see OPT as a tool for investigating links between odours and emotion. Whether it can distinguish subtle impressions or handle more odours at once remains to be tested. The present task was limited to two feeling categories; it does not capture complex impressions such as nostalgia or sensuality in a single assessment.
The participants were affiliated with the company, not a random sample of perfume consumers. Three authors also disclosed employment at DSM-Firmenich.
Summary
With both single odorants and finished perfumes, people tended to respond more quickly to associated feeling words at the first presentation. This provides a way to examine links between scent and mood-related impressions beyond whether a fragrance is liked.
Self-ratings and word reaction times approach fragrance impressions from different angles. Combining them may enable more detailed investigation of how consumers experience scents. The study offers a measurement method while identifying questions about its precision and underlying mechanisms that still need to be resolved.
References
Cereghetti, D., Coppin, G., Porcherot, C., Cayeux, I., Sander, D., & Delplanque, S. (2024). Beyond self-report measures of arousal: A new priming task to capture activation of relaxing and energizing feelings elicited by odors. Food Quality and Preference, 119, 105227. DOI: 10.1016/j.foodqual.2024.105227 / Full text. Original article license: CC BY-NC 4.0.
