Scientists found a subtle social cue that reveals your choices

An experimental study in Israel found that participants were more likely to prefer a movie synopsis when their positive facial expressions mimicked the facial expressions of the person they were interacting with. This facial mimicry predicted participants’ choices better than the participants’ own facial expressions alone. The paper was published in Communications Psychology.

Facial mimicry is the tendency to spontaneously and often unconsciously reproduce the facial expressions we observe in other people. When someone smiles, frowns, or shows another emotion, our own facial muscles may respond with a subtle version of the same expression.

This behavior appears very early in life and has been linked to empathy, emotional understanding, social bonding, and affiliation. Mimicry may help us understand other people by partially recreating their emotional state in our own facial muscles and brain systems.

At the same time, it is not simply an automatic reflex, because people mimic others more or less depending on social context, relationships, goals, and whether an emotional expression seems appropriate to the situation. People are also generally more likely to mimic individuals they like, identify with, cooperate with, or regard as socially important.

Study author Liron Amihai and colleagues conducted a study in which they explored whether facial mimicry can predict preferences in a situation when people choose between two options during natural, two-person interactions. They hypothesized that facial mimicry would predict participants’ choices and that it would be a more accurate predictor of these choices than facial expressions alone.

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Study participants were 120 women. Their average age was 23 years. They were grouped into pairs, and the researchers made sure that members of a pair did not know each other previously.

The study authors selected 16 book synopses from GoodReads.com as stimuli to be used in the study. They were selected from a wider set of 25 books that were released around the time of selection, for which there was no previous Hebrew translation, and that did not have notable popularity in Israel.

The synopses of these books were rated by a different group of 30 participants, and the study authors selected a set of 16 synopses that received similar ratings. Although the synopses were derived from books, the study authors presented them as movie synopses to the study participants. Of the 16 synopses, they chose 8 and recorded an actress reading them.

At the start of the experiment, the study authors fitted electromyography (EMG) electrodes—small sensors used to measure the electrical activity of muscles—on participants’ faces, allowing them to track participants’ facial movements. They then calibrated the system by asking participants to imitate the facial expressions of an actor in a video.

After that, they proceeded to the reading phase of the experiment. In this phase, one participant in the pair read two selected synopses to the other member of the pair, while that member was seated opposite and was able to view the reader’s face. After reading the synopses, each participant indicated which movie they would prefer.

In the listening phase, participants in a pair remained seated face to face, but listened to two synopses read by an actress (the one the study authors previously recorded, audio only). In two of the four trials, they were instructed to indicate which of the two movies they preferred, and in the other two, they indicated which of the two movies their partner would prefer.

Results showed that participants were more likely to choose a synopsis when they showed higher levels of facial mimicry of muscles associated with positive emotions. As the study authors hypothesized, the listener’s choice was better predicted by the speaker-listener’s facial mimicry than by the listener’s own facial expressions alone. The results remained the same even when only smiling mimicry was measured in the listening situation (i.e., in the part of the experiment where they listened to the audio recording of the actress reading the synopses).

“Our findings suggest that facial mimicry is a powerful non-verbal cue that is correlated to and might influence agreement, interpersonal judgments and preferences, offering important implications for understanding the mechanisms behind social cognition and interaction,” the study authors concluded.

The study contributes to scientific knowledge of the role of facial mimicry in interpersonal interactions. However, it should be noted that the study focused exclusively on women. Results on men might differ.

The paper, “Facial mimicry predicts preference,” was authored by Liron Amihai, Elinor Sharvit, Hila Man, Yael Hanein, and Yaara Yeshurun.