Talk about opinion leaders and their constraints and effects on the effectiveness of mass communication.

Answer: Opinion leaders are an important concept proposed by Lazarsfeld and others in the bipolar communication theory, which refers to those people in the crowd who are first or more exposed to mass communication information and spread the information after their own reprocessing to others. Opinion leaders intervene in the communication process, speeding up the process of information dissemination and expanding the impact of the disseminated information. They are characterized by: (1) the ability to influence and change the attitudes of others; (2) being more active in social situations; (3) being in the same group as the people they influence and having *** the same hobbies and interests; and (4) being knowledgeable about a particular issue and being willing to accept and disseminate information in this regard. In modern communication practice, the influence of opinion leaders on communication should be recognized, and the interpersonal communication effectiveness of opinion leaders should be used to improve the effectiveness of communication.