Newswise — A new study suggests that a person’s sense of smell may reveal a weight bias, one that is likely more pervasive than previously believed.

The study, which was first reported in the International Journal of Obesity, discovered that visual cues associated with overweight or obese individuals can influence a person’s sense of smell.

“This is the first study to show that negative bias toward heavy individuals — something that is initially a visual experience — could transfer into an olfactory or smell experience,” says Andrew Ward of Swarthmore College, who worked on the study with A. Janet Tomiyama and Angela Incollingo Rodriguez, both of UCLA.

In two related studies, the team of researchers showed subjects one of two sets of images. Both sets contained photographs of different people — half who were visibly overweight or obese, and half who were normal weight or thin — along with a series of distractor objects.

Each image was paired with a scent sample — a fragrance-free lotion (Eucerin) mixed with two drops of food coloring.

As each image appeared, the experimenter placed the scent sample under the participant’s nose. Participants were instructed to rate each scent from 1 to 11. The more positive the rating, the more positive the reported smell.

The researchers found that when overweight or obese people were on the screen, participants gave worse ratings to the scent samples, despite the fact that the samples were unscented. Images of average-sized or thin people tended to trigger higher ratings.

The study also discovered that the perceiver’s body mass index (BMI) mattered. Participants with higher BMI tended to be more critical of heavier people, with higher-BMI participants giving scents a lower rating than lower BMI participants when scent samples were matched with an obese or overweight individual.

“It suggests that there isn’t a “self-enhancement” bias among people who are the target of the stigma,” Ward adds.

Going forward, Ward hopes the methodology used in the study can be useful in identifying other forms of bias, not just weight.

“We may have developed a new method for uncovering unconscious bias in individuals that they would normally not be willing to admit.”

If you are interested in speaking with Professor Ward about the study, please contact Mark Anskis in the Swarthmore College communications office ([email protected] /610-328-8271).

Journal Link: International Journal of Obesity