Human communication consists of an intricate combination of verbal and non-verbal signals. We shall see that the verbal aspects of messages are elaborated and supported in a number of ways by non-verbal ones. In order to understand human verbal communication we need to know about these non-verbal components. Non-verbal communication can be studied experimentally as a problem in encoding and decoding; it can also be studied as part of a sequence, using the methods of ethology or of linguistics. We shall (...) see that this kind of analysis has theoretical implications about the nature of human communication, and has practical implications in a number of fields. (shrink)