How other people's emotions affect our sense of smell

Whether something smells good or bad isn't solely a matter of the nose. The emotional expressions of others influence how we perceive a given scent—positively or negatively. This effect appears to be based on a brain area relevant to smelling, which activates before we begin to perceive the scent.

The above statement was made by neuropsychologists from Ruhr-Universität Bochum. They published their findings in the journal Scientific Reports. When we see someone contorting their face because they smelled an unpleasant odor, the same odor also seems unpleasant to us , says Dr. Patrick Schulze, one of the authors of the study.

The same scent always smells different

Dr. Schulze's team used functional magnetic resonance imaging (fMRI) to investigate how the brain processes the combination of emotional information and odors. Participants viewed a photo of a person with a happy, neutral, and disgusted facial expression. They were then asked to rate one of 12 odors. The facial expression image influenced the perception of odors. Participants rated the odor higher when first shown a happy face. When first shown a disgusted face, they rated the odor lower. These ratings were for caramel, lemon, garlic, and sweat. Only the odor of feces was not "rewarded" by a positive facial expression.

Expectations influence reception

The piriform cortex—a specific part of the olfactory brain—is responsible for these different perceptions. This brain region activates before a person detects an odor. The piriform cortex processes what we see and creates expectations about what something will smell like. These expectations influence how we perceive smell. Functional magnetic resonance imaging data showed that cells in the piriform cortex were activated before the odor began to waft through the air. "In previous studies, scientists always presented participants with images and smells at the same time. Only now, when we analyzed the interplay of olfactory and visual information at the appropriate moment, could we see that the piriform cortex is activated before we smell anything, " explains Dr. Boris Suchan.