Smiling during conversations often elevates the experience of knowing someone, but this understanding has been subjective. A new study by Fujita Health University researchers investigated the reciprocal relationship between people who indulge in smiling during face-to-face conversations. The researchers found that speakers smile more when listeners smile more, particularly in paired individuals of the same biological sex. These findings provide evidence of synchronized smiling behavior, highlighting the influence of facial expressions on interpersonal relationships.