identity and, consequently, trigger increased processing. In some circumstances, for example, when the message was strong, this increased processing could result in acceptance of an appeal delivered by an outgroup member.
At a more general level, this program of research highlights the important impact of who says what to whom. The identity, shared or otherwise, of the individuals in source and audience roles can have considerable impact on both the processing and eventual effectiveness of persuasive appeals. Such results remind us that even when message variables appear to determine persuasion, the cognitive processes that mediate their effectiveness often presuppose, assume, and depend on an appropriate social context. The role of assumed consensus or social agreement, for example, seems to be a particularly important concept that should receive more attention in persuasion research. As Kelley ( 1952) made clear, consensus information is a powerful determinant of informational validity, leading as it does to external attributions. In addition to the impact that explicit consensus has in conformity and majority influence situations, consensus may have much wider effects because it is implicitly assumed. Phenomena such as false consensus and pluralistic ignorance no doubt owe their persuasive capacity to perceived consensus. Additionally, the persuasive power of statistical and expert evidence also may reside in their appearing to embody an appropriate consensus. Thus, social processes are just as essential to conferring validity on information and producing persuasion as are the more popularly investigated cognitive processes. With the means of assessing the processing pathways by which distal factors make their persuasive contribution now in hand, the time is ripe for a return to concern with social psychology's early focus on the social roots of persuasion and an integration of the persuasion and social influence literatures is now in order.
This chapter was written with the partial support of Grant SBR 9507628 from the National Science Foundation to Diane Mackie and a National Science Foundation Graduate Fellowship to Sarah Queller.