For Years Communications Practitioners have been vitally concerned with their believability. Since Aristotle's famous treatise on rhetoric, propagandists, ministers, writers, advertisers and other professional persuaders have sought the key to belief. The one group which has paid most attention to the believability of persuasive communications is advertisers.

Two basic premises have been implicit in advertisers’ traditional investigations of believability: first, that there are two alternative and mutually exclusive audience reactions to an advertisement once it has been noticed and understood: people will either believe it or disbelieve it; and second, that consumers’ overt analyses or ratings of an ad's content predict its effect.