I am no expert in this matter, but the Yale Model of communication and attitude, developed in the 1950s, set out supposed rules about the relationship between communicators and their audience, especially in situations where the communicators are trying to persuade the audience to change their behaviour - for example in health education. I haven't found any websites which are very clear on the basics of the Yale Model - most of them seem to take its tenets for granted - but the following may be helpful:
http://users.ipfw.edu/bordens/social/persuas.htm
Consulting a textbook on social psychology may be your best bet.