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A smile can also cause a lot of stress


Facial expressions regulate the world

A smile is primarily interpreted as an act of kindness and warmth. But not every smile is positive. The human body reacts very differently to the different nuances of the smile. In a recent study, American scientists examined the effects of smiling on the human body.

A team of researchers led by Jared Martin, a doctor of psychology at the University of Wisconsin-Madison, is studying the physical reactions that a smile from the other person can cause in the study. A rewarding or warm smile can lower the partner's stress level and strengthen the bond. In contrast, a dominant, superior smile can result in an increase in stress hormones. The results of the study were recently published in the scientific reports.

Facial expressions regulate the world

"Our results show that subtle differences in the way facial expressions are used during a conversation can fundamentally change the body and feeling of the interlocutor," explains Martin in a press release from the university on the study results. "Facial expressions really regulate the world," says Martin.

The main types of smiles: dominance, belonging and reward

Martin works closely with the psychology professor Paula Niedenthal, whose emotional research has established three main types of smiles: dominance, belonging and reward. The dominant smile should convey the other person's own status. The belonging smile should strengthen the connection between the conversation partners and show that you are not a threat. The rewarding smile shows that you made someone happy.

Course of the study

In the study, 90 subjects had to give short speeches via a webcam and saw the reactions of the listeners to a screen. In fact, the responses were previously recorded responses, each with a certain type of smile, either reward, belonging, or dominance. In the meantime, the researchers monitored the speakers' heart rate and regularly took saliva samples to measure the stress hormone cortisol.

Dominant smiles caused stress

“When the test subjects got a dominant smile that they interpreted as negative and critical, they felt more stress,” says Niedenthal. As a result, her cortisol level also rose and remained elevated for a long time after the speech. In contrast, the rewarding smile was interpreted as approval and resulted in the subjects feeling less stress and producing less cortisol. The associated smile was more difficult to interpret in this context by the test subjects, but came closer to the effect of the rewarding smile.

People deal with social information differently

"People differ in how tolerant or able they are to deal with or understand social information," says Niedenthal. The parasympathetic nervous system, which manages breathing and heart rate, is responsible for the reactions.

Diseases can change reactions

"Heart rate variability is not innate and unchangeable," explains Martin. Some diseases and disorders such as obesity, cardiovascular disease, autism, anxiety and depression can pull heart rate variability down. This in turn could lead to people recognizing social signals such as dominance and reward more poorly and reacting differently.

Stress changes perception

"We are all individuals: one may be really scared, the other in good shape," Martin sums up. The things we carry around change the way we perceive the world in a very sensitive and personal way, the expert says. (vb)

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