Stress Sweat May Make Women Seem Untrustworthy, Study Suggests

Stress sweat isn't just stinky and unsightly: For women, it could also affect how they are perceived, a new study suggests.

Published in the journal PLOS ONE, the research shows that women with stress sweat -- sweat that comes about because of a stressful condition, which is different from sweat that comes from exercise or from heat -- are more likely to be perceived as untrustworthy or lacking in confidence.

The study was conducted by researchers at the Monell Chemical Senses Center. While Proctor & Gamble Beauty provided funding, the study said "the funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript."

Forty-four women participated in the study by offering up samples of armpit sweat that came from three different conditions: sweat from 15 minutes of exercise, stress sweat and stress sweat that had been treated with P&G's Secret Clinical Strength deodorant. The stress sweat was induced by having the women undergo the Trier Social Stress Test, which involved five minutes each of public speaking, speech preparation and mental arithmetic.

After all the sweat samples were obtained, researchers had 120 other study participants, both male and female, come in to judge perceived stress, confidence, trustworthiness and competence of the women based on the sweat. They smelled the sweat samples from the three conditions, and also watched videos of the women who offered up the sweat samples as they went about everyday lives.

Stress sweat stunk in the ratings. When males smelled the stress sweat and watched the videos of the women, they perceived the women as being less confident, trustworthy and competent, than when they smelled the treated stress sweat. However, these social judgments were only held by men; women did not seem to find a difference in confidence, trustworthiness or competence between the three sweat sample conditions.

Both men and women were, however, equally likely to say that the women were stressed when they smelled untreated stress sweat and watched the videos of the women. The two groups also rated the women in the videos as being more confident, trustworthy and competent when they smelled the treated stress sweat.

TIME explained the difference between stress, exercise and heat sweat:

Each is driven by a slightly different body process -- exercise and heat sweat come from the body’s eccrine glands, which pump out clear, odorless water on the surface of the skin that is tinged with a bit of salt (these are the glands responsible for damp foreheads and clammy palms and feet). Stress sweat, however, comes from the more hirsute regions of the body -- think scalp, armpits and groin -- and is saturated with fats. Those aren’t odoriferous per se, but they serve as food for the bacteria that blanket the skin, and it's those bugs that emit the hallmark BO signalling sweat under pressure.

Sweat isn't the only thing that can affect perceived trustworthiness. Another study published earlier this year in the same journal showed that eye color can influence how likely we are to trust someone. Researchers from Charles University in Prague and the Universite Laval in Canada found that people think brown-eyed humans are more trustworthy than blue-eyed humans. However, some of this perception could actually be due to face shape rather than eye color, researchers noted.