New study reveals the power of smile synchronization

Smiling during conversations creates warmth, making people feel more comfortable and connected. For example, a friendly smile when meeting someone new can ease nervousness. A smile can soften tension in a debate, showing respect among the participants despite disagreement. In fact, extensive studies have been conducted in the past in an attempt to understand smiling interactions in a natural conversation. Despite these studies, however, little is known about the extent to which one's smile influences or gets affected by the other person's smile during a conversation.

A new study sought to investigate this by quantifying the influence of smiling in face-to-face conversations. The study, led by Professor Yohei Otaka from the Department of Rehabilitation Medicine, Fujita Health University School of Medicine, Japan, found that the amount of smiling by the speaker increased as the listener's smile intensity increased, particularly in same-sex pairs. The study also involved lead researchers Dr. Yota Obayashi, Dr. Shintaro Uehara, and Dr. Akiko Yuasa from the same university. Their findings were published in Frontiers in Behavioral Neuroscience on 09 August 2024.

The main purpose of this study was to develop a methodology for assessing dementia symptoms, given the affected individuals tend to lose their facial expressions. We also intend to evaluate the rehabilitation treatment efficacy in these individuals." Adding further, he says, "This study is, in fact, the first step towards the larger, above-mentioned goal by evaluating the reaction of people to the smile of others in young healthy participants."

Yohei Otaka, Professor, Department of Rehabilitation Medicine, Fujita Health University School of Medicine

The study involved 40 participants (20 men and 20 women) in three-minute, face-to-face conversations. During these interactions, listeners were asked to smile at different levels-;lesser, moderate, and greater-;and the speakers' smiles were observed in response. A specialized software was used to measure the intensity and frequency of the smiles during the conversations.

Results revealed that speakers smiled more when listeners smiled more, especially in conversations between two individuals of the same-sex-;men smiled more when talking to other men who smiled, and women smiled more when talking to other women who smiled. Interestingly, this effect was less pronounced in mixed-sex conversations, suggesting that individuals did not show the same level of mutual smiling as they did when conversing with same-sex partners. However, the researchers speculate that in mixed-sex pairs, the speakers smiled more often than the listeners in order to build interpersonal relationship.

Another key finding was that the more the listener smiled, the more positive the speaker felt about the interaction. Speakers reported feeling friendlier and enjoying the conversation more when their partner smiled frequently. This finding highlights the emotional importance of smiling in conversations, as it enhances feelings of connection and rapport between individuals. Explaining these findings further, Prof. Otaka says, "If one smiles more during a conversation, the other person will also smile more, which can lead to a better interpersonal relationship with each other."

Additionally, the study found that smile synchronization occurred consistently across all types of pairs-;both same-sex and mixed-sex. This implies that, regardless of who was talking to whom, people smiled simultaneously, reinforcing that smiling is a reciprocal behavior.

In summary, the study reveals that smiling is a powerful, dynamic part of face-to-face conversations. Speakers' smiles are influenced by how much and how intensely the listener smiles, particularly in conversations between individuals of the same-sex. Also, smile synchronization is essential in creating social bonds and fostering positive feelings during interactions.

These findings emphasize the importance of nonverbal communication, especially facial expressions, in everyday conversations. Furthermore, this study suggests that the interaction between two individuals can be helpful in assessing dementia and psychological dysfunctions.