If there’s one thing drilled into us as we begin a career in fragrance evaluation, it’s that panelists should come to the test session free of scent. This makes sense inside the industry—if you want accurate judgments about a trial perfume, you don’t want the assessments muddled by other brands. In fact, we often take it further and don’t wear our own personal scents when visiting a client—we want the focus entirely on the sample we’re showing.
The same taboo is widely observed in academic smell research. It’s a reasonable precaution when conducting a study on human body odor, but a bit of a stretch when the panelists are sniffing dish detergent or shampoo. After all, the real world is a constantly changing smellscape and we experience these products in that context. One wonders: does the prohibition make any difference to the test results?
What is remarkable about the taboo on scented panelists is that, like a lot of conventional wisdom, it has never been put to the test. At least until now.
Beekman et al. at the University of Arkansas have taken a swing at the issue. Over the course of three test sessions they had panelists “wear” (on scented smocks) either no scent, a “just about right” amount of perfume, or “excessive” perfume. All panelists, male and female, were given the same unisex fragrance, namely Marc Jacobs Decadence EDP. Then the panelists were given the full Sniffin’ Sticks olfactory test battery (threshold, discrimination, and identification tests).
The results were pretty clear: odor threshold and odor discrimination were significantly reduced with increasing doses of Decadence. However there was no effect on odor identification.
The way I read it, the presence of perfume interfered with technical measures of odor perception, but not with the more robust real world task of odor identification. It’s the rare consumer research study that inquires about minimum perceptible concentration (threshold) or about fine differences between samples; that sort of discrimination task is left to trained panelists.
The authors discuss their results with respect to adaptation, defined as a “decrease in sensitivity or response to an odor stimulus following repetitive stimulation.” But is that what they actually studied? The repetitive stimulus was a Marc Jacobs perfume, while the response probes were a selection of (unspecified) smells in the Sniffin’ Sticks battery. The authors make no attempt to cross-reference the probes to the perfume. For example, if there was a rose note in the test battery and a rose note in Decadence, were the rose test items differentially affected?
In the end, I’m glad they did the study. But I’m not sure the effects they found have much consequence for typical consumer research on scent.
Thadeus L. Beekman, Kaushik Luthra, Shady Afrin Jeesan, Rebecca Bowie and Han-Seok Seo. (2022). Should panelists refrain from wearing a personal fragrance prior to sensory evaluation? The effect of using perfume on olfactory performance. Foods 11:428.