The way of communicating between people involves different implicit rules. There is of course the posture, the eye contact, and the gestures, which send a message to the other person on the inclination to enter in contact or not. Once two people are in contact, a certain rhythmicity is set in between them. This rhythmicity is a way of varying the flow of the speech, to adopt that of the other; or a way of exchanging moments of silence and speech. In fact, getting in touch is partly aiming to synchronize in order to be predictable for the other.