People in conversation highly mesh their bodily movements with each other. For instance, turning their gazes on the same object to share attention, showing similar postures or facial expressions when conversing in tune, synchronizing the speed of speaking or voice inflection, mimicking unconsciously the others' gestures. Conversation is not only the exchange of verbal information but also is the embodied interaction. Nonverbal behavior as embodied interaction probably underpin and facilitate the verbal communications.
Bernieri and Rosenthal conceptualize this kind of behavior meshing as 'interpersonal coordination'. Interpersonal coordination is "the degree to which the behaviors in an interaction are nonrandom, patterned, or synchronized in both timing and form". It can be categorized into two basic types: (1) behavior matching and (2) interactional synchrony.
[Bernieri, F. J. & Rosenthal, R. (1991). Interpersonal coordination: behavior matching and interactional synchrony. in Fundamentals of Nonerbal Behavior. Cambridge U. P., pp.401-432.]
1. Behavior matching
Congruence and similarity of physical behavior between interactants. Two people conversing may posture similarly, lean forward and back, or have their arms or legs crossed in the same way. They may appear to be mirrored reflections of each other.
2. Interactional synchrony
Timing aspect of interaction such as shared rhythm, simultaneous movement, and smooth meshing of interaction. Some interactions occur in a rapid fashion, others are slower or more fluid. Based on the shared rhythm, the interactants are entrained to a certain behavioral cycle and show the simultaneous movements in body orientation, postural change, gaze, vocal activity, facial expressions and so forth. This synchronization enables to mesh interactions of each other.
From the phenomenological side, interpersonal coordination in communication might be re-interpreted from the viewpoint of intercorporeality.