When trying several perfumes, you may be offered coffee beans before smelling the next one. Smelling something different is supposed to make the perfumes easier to distinguish again. How much evidence is there for this kind of “nose reset”?
In 2011, Alexis Grosofsky and colleagues at Beloit College in the United States published an experiment comparing coffee beans, lemon, and air after repeated exposure to commercial perfumes. They asked whether what people smelled between samples changed their ability to identify a perfume they had not smelled before.
Finding the fourth perfume after smelling three
The participants were 63 college students. The researchers sprayed four commercial fragrances onto blotter paper, let the paper dry, and placed it in small vials. Participants smelled and rated three of the fragrances three times each. Asking them about pleasantness, intensity, and other impressions provided a reason to smell the same fragrances repeatedly.
After nine smelling trials, participants were randomly assigned to one of three conditions. They smelled coffee beans, lemon slices, or air in an unscented container for 10 seconds. They were then given the three previous fragrances and one new fragrance and asked to identify the one they had not smelled before.
No advantage was demonstrated for coffee beans
The new fragrance was correctly identified by 57% of participants after air, 62% after coffee beans, and 86% after lemon. Although these percentages differ, the difference among the three conditions was not statistically significant. The experiment did not find that coffee beans improved identification performance.
The highest percentage for lemon is not grounds for concluding that lemon can reset the nose, either. Nor does the absence of a significant difference prove that the three methods are exactly equivalent.
Was the nose sufficiently fatigued in the first place?
An important point when reading this study is that the authors themselves acknowledged that the experiment might not have induced sufficient olfactory fatigue. Randomly choosing among four fragrances would give a 25% success rate, but more than half the participants answered correctly in every condition. The authors interpreted this performance as suggesting that fatigue had not reached the point of preventing fragrance discrimination.
The experiment therefore does not directly show which method restored a thoroughly fatigued sense of smell. Neither the duration of smelling nor the amount inhaled was tightly controlled, and participants did not receive a formal test of olfactory ability. The familiar procedure of picking up a vial to smell it also made precise control of conditions more difficult.
Conclusion
This small experiment did not demonstrate any special benefit from smelling coffee beans between perfumes. The authors suggested reconsidering the retail practice. However, because recovery from substantial olfactory fatigue was not established, the findings cannot be extended to mean that coffee beans are useless in every situation.
Putting this into practice when trying perfumes
One possible takeaway for everyday sampling is not to assume that your nose is back to normal simply because you have smelled coffee beans. If the differences become unclear, rather than trying to decide everything on the spot, note the perfumes that interest you and leave room to try them again. This was not a strategy whose effectiveness the study compared, but it is a way to avoid rushing to a judgment about your own impressions.
References
Authors: Alexis Grosofsky, Margaret L. Haupert, Schyler W. Versteeg
Article: An Exploratory Investigation of Coffee and Lemon Scents and Odor Identification
Journal: Perceptual and Motor Skills 112(2), 536–538 (2011)
DOI: 10.2466/24.PMS.112.2.536-538
