A crucial issue in communication research relates to the nature of changes (if any) that are brought about by a particular communication or type of communication. It is not enough to know that there has been some measurable change in attitude; usually we would also want to know what kind of change it is. Is it a superficial change, on a verbal level, which disappears after a short lapse of time? Or is it a more lasting change in attitude and belief, which manifests itself in a wide range of situations and which is integrated into the person?s value system? Or, to put it in other terms, did the communication produce public conformity without private acceptance, or did it produce public conformity coupled with private acceptance? (Cf. 1, 4.) Only if we know something about the nature and depth of changes can we make meaningful predictions about the way in which attitude changes will be reflected in subsequent actions and reactions to events.