A new study says it has confirmed for the first time that the smell of stress sweat does  significantly alter how women are perceived by both males and females.

Research has shown the ability of human body odor to communicate information between individuals. Not only have body odor signals been shown to convey messages about genetic connection, dating and general health, but body odors produced from individuals in specific emotional states have been shown to affect both the neural and behavioral states of the receiver, whether or not they are consciously aware of the source of the body odor. 

Researchers sampled 44 female donors who provided three types of axillary odor samples including; exercise sweat, stress sweat (untreated) and stress sweat (treated with Secret Clinical Strength deodorant). Results of the study indicate that these chemosignals of stress specifically impact social judgments of one's confidence, trustworthiness and competence.

"Researchers have studied the impact of stress sweat on emotional states and brain activity, but we have not previously evaluated how it influences social perception," said lead investigator Pamela Dalton, PhD. MPH, member of the Monell Chemical Senses Center. "For the first time, we have found that stress sweat odor impacts overall judgments of perceived confidence, trustworthiness and competence."


Mean and standard errors of the confidence, trustworthiness and competence ratings of the women depicted in the videos as a function of the sweat odor pairing condition. doi:10.1371/journal.pone.0077144.g003

"Stress-induced sweat, the worst smelling of the three causes of sweat, can occur unexpectedly at any point in the day, often becoming a vicious cycle. Research demonstrates there are three causes of sweat: physical exertion, environmental heat and stress. Sweat caused by physical activity (internal thermal stress) and environmental heat (external thermal stress) are produced by secretions from the eccrine sweat gland, while stress (emotional) sweat is produced by secretions from the eccrine and apocrine gland." said Dr. Susan Biehle-Hulette, Procter & Gamble and Secret brand senior scientist for product development, "and as this sweat mixes with bacteria on our skin, the result is a distinguishably foul odor."


Study Methodology


Participants wore comfortable clothes for exercising that would allow access to the underarm for sample collection, and were seated in a climate-controlled chamber where baseline recordings of heart rate and mood were obtained.

A different experimenter then administered the Trier Social Stress Test (TSST) which was comprised of:

  • Five minutes of speech preparation
  • Five minutes of mental arithmetic
  • Five minutes of public speaking

After the TSST, participants were asked to fill out the mood ratings and sweat samples were obtained. The participants were then informed they would exercise on a stationary cycle for 15 minutes and sweat samples would be collected as well as mood ratings.

Once the test was completed, 120 male and female evaluators, presented with samples of each type of sweat, watched videos of women performing every-day activities (office, home, childcare, etc.) in order to rate how stressed each woman appeared. All evaluators rated the females with treated stress sweat as significantly more confident (p=.02), trustworthy (p=.03) and competent (p=.048).

Results

Women evaluated in the presence of untreated stress sweat were equally rated by males and females as 'stressed.' In addition, male evaluators rated the women in the videos significantly less confident, competent and trustworthy when the videos were paired with the untreated stress sweat.

Citation: Dalton P, Mauté C, Jaén C, Wilson T (2013) Chemosignals of Stress Influence Social Judgments. PLoS ONE 8(10): e77144. doi:10.1371/journal.pone.0077144