A Source Like Any Other? : Field and Survey Experiment Evidence on How Interest Groups Shape Public Opinion

Abstract

Interest groups increasingly communicate with the public, yet we know little abouthow effective they are in shaping opinions. Since interest groups differ from otherpublic communicators, we propose a theory of interest group persuasion. Interestgroups typically have a low public profile, and so most people are unlikely to havestrong attitudes regarding them. Source-related predispositions, such as credibilityassessments, are therefore less relevant in moderating effects of persuasive appeals byinterest groups than those of high-profile communicators. We test this argument inmultiple large-scale studies. A parallel survey and field experiment (N¼4,659) estab-lishes the persuasive potential of low-profile interest groups in both controlled and re-alistic settings. An observational study (N¼700) shows that substantial portions ofthe public are unable to assess interest group credibility. A survey experiment(N¼8,245) demonstrates that credibility assessments moderate the impact of partybut not interest group communication.