Smile and you'll be believed: what psychologists have found out

Psychologists have found that smiling triggers a chain of trust in just seconds: we are more likely to involuntarily copy a happy facial expression and then evaluate a smiling person as more trustworthy and attractive. The work by an international team of scientists, including researchers from SWPS University and Humboldt University Berlin, is published in the journal Emotion.

What is emotional mimicry and why is it important

In everyday communication, people often "adjust" to each other: they repeat facial expressions, intonations and gestures. In the case of emotions, this is called emotional mimicry - when we, without noticing it, slightly repeat the smile, frown or expression of sadness of the interlocutor. Scientists believe that this "mirror" mechanism helps to understand the intentions of another person faster and strengthens social ties.

How the hypothesis was tested

The authors conducted three experiments where participants evaluated faces with expressions of joy, sadness and anger. Two of the experiments used facial electromyography (EMG), a technique that records the micro-movements of facial muscles to accurately measure how much a person "copies" the emotion they see.

• In the first experiment, people gave ratings of trustworthiness, attractiveness and confidence, and EMG showed: smiles were mimicked markedly more often than sadness or anger.
• In the second experiment, the researchers tested causality: whether another person's evaluation of another person changes if the participant's facial expressions artificially "nudge" imitation (or, conversely, interfere with it). The results supported the idea that happiness mimicry is associated with increased trust and may be a causal factor.
• In the third experiment, trust was measured by behaviour - through an 'investment game' where participants decided how many virtual points to give to a partner. Smiling faces were more likely to trigger mimicry and provoked more trusting behaviour.

Key finding

The study confirms a popular intuition: smiling people are more likely to be considered more trustworthy. But an important detail - trust is not only related to the fact that a person smiles, but also to how much you yourself (albeit imperceptibly) "picked up" his smile: the more intense the mimicry of joy, the higher the trust in the first impression.