R. Glen Hass Brooklyn College, City University of New York
A high proportion of the knowledge and attitudes that each of us possesses about our world was obtained from other people, and some persons who provide us with information have an easier time persuading us than others. The recognition that the persuasive impact of a communication can differ depending on the characteristics of its source stimulated some of the first carefully controlled experiments on the attitude change process (e.g., Hovland, Janis, & Kelley, 1953; Hovland, Lumsdaine, & Sheffield, 1949). The goal of those early experiments and much of the research on the persuasiveness of message sources during the next three decades was to identify specific characteristics of persuasive sources rather than to develop theoretical explanations for the phenomena.
Of course, it is important to know the characteristics that make a source more influential and the limits of those effects from situation to situation. This knowledge is important for many practical purposes. For example, who would you rather have act as your defense attorney before a jury in a small town -- a wellknown, prestigious New York lawyer or a country lawyer from the same small town? Who would be the better choice as the communicator in a television commercial for a new family car -- a well-known actor or actress, an engineer, or, the members of a "typical family"? Or in a commercial encouraging people to use car pools -- the actor or actress, a respected political figure, an environmental scientist, or an "average" commuter?
However, the knowledge of the persuasive effects of source characteristics and their limitations is also important for subsequent theory building. This chapter reviews some of the major findings of research designed to investigate the