<P> Some time has been spent analyzing the means by which the propaganda messages are transmitted . That work is important but it is clear that information dissemination strategies become propaganda strategies only when coupled with propagandistic messages . Identifying these messages is a necessary prerequisite to study the methods by which those messages are spread . </P> <P> The field of social psychology includes the study of persuasion . Social psychologists can be sociologists or psychologists . The field includes many theories and approaches to understanding persuasion . For example, communication theory points out that people can be persuaded by the communicator's credibility, expertise, trustworthiness, and attractiveness . The elaboration likelihood model as well as heuristic models of persuasion suggest that a number of factors (e.g., the degree of interest of the recipient of the communication), influence the degree to which people allow superficial factors to persuade them . Nobel Prize--winning psychologist Herbert A. Simon won the Nobel prize for his theory that people are cognitive misers . That is, in a society of mass information, people are forced to make decisions quickly and often superficially, as opposed to logically . </P> <P> According to William W. Biddle's 1931 article "A psychological definition of propaganda", "(t) he four principles followed in propaganda are: (1) rely on emotions, never argue; (2) cast propaganda into the pattern of "we" versus an "enemy"; (3) reach groups as well as individuals; (4) hide the propagandist as much as possible ." </P> <P> The propaganda model is a theory advanced by Edward S. Herman and Noam Chomsky which argues systemic biases in the mass media and seeks to explain them in terms of structural economic causes: </P>

Which is the most accurate statement of the purpose of the media piece