Nonverbal synchrony denotes the temporal coordination of motor behavior of two or more interacting individuals (i.e., “interactants”). It is given when the body motion of interactants is positively or negatively correlated to a degree exceeding random correlations. The existence and extent of nonverbal synchrony in various social situations are subjects of psychological research. Individuals in a conversation, for instance, synchronize not only their verbal utterances (“turn taking”) but also their body movement. During conversation, nonverbal synchrony arises when both interactants move in response to each other, by coordinating posture changes, seating positions, gestures, facial expressions, or head movements. Movements that have emotional expressive function, ranging from laughing to applauding to yawning, have been found to be socially contagious (i.e., they also occur in a synchronized ...