It’s well-known that a person’s sense of smell is associated with taste. But could the way we smell things also be determined by how we see it, say, on labels? A new study by researchers at the University of Montreal’s Department of Psychology looked into exactly that, testing how people perceived scents based only on their descriptions. As you might expect, they were pretty easily influenced.
For the study, researchers recruited 50 people, all of whom were asked to smell four distinct odors: essential oils of pine, geraniol (used in perfumes and soap, and the primary part of rose oil), cumin, and parmesan cheese. Each participant was asked to smell the odors, which were randomly given a positive or negative description, through a mask. The scent for pine oil was described as either “pine needles” or “old solvent." Geraniol was presented as “fresh flowers” or “cheap perfume.” Cumin was given the label of “Indian food” or “dirty clothes.” And parmesan cheese was described plainly as “cheese” or as “dried vomit.”
Every single participant rated the positive descriptions better than the negative descriptions. They even went so far as to describe the positive odors as not only pleasant, but edible — why someone would want to eat pine needles deserves another study. Those who rated the negatively-labeled odors badly also said that they were inedible. “It shows that odor perception is not objective, it is affected by the cognitive interpretation that occurs when one looks at a label,” Simona Manescu, a co-author of the study, said in a press release. Johannes Frasnelli, another co-author of the study, added: “Moreover, this is the first time we have been able to influence the edibility perception of an odor, even though the positive and negative labels accompanying the odors showed non-food words.”
A human’s sense of smell, known as olfaction, is often considered to be the least powerful of the senses. Of the 1,000 genes in the olfactory gene family, only about 350 encode olfactory receptors in humans — these allow for distinction of odors. By comparison, dogs have about 811 working olfactory receptors. With less working receptors, it’s much easier for us to become confused by what we smell. Researchers from a 2001 study looking into basically the same thing as Frasnelli and Manescu called this an olfactory illusion, because although the “stimulus is invariant,” its “context alters its perception.”
Source: Manescu S, Frasnelli J, Lepore F, et al. Now You Like Me, Now You Don’t: Impact of Labels on Odor Perception. Chemical Senses. 2014.