Opinion leadership is leadership by an active media user who interprets the meaning of media messages or content for lower-end media users. Typically the opinion leader is held in high esteem by those who accept their opinions. Opinion leadership comes from the theory of two-step flow of communication propounded by Paul Lazarsfeld and Elihu Katz. Significant developers of the theory have been Robert K. Merton, C. Wright Mills and Bernard Berelson. This theory is one of several models that try to explain the diffusion of innovations, ideas, or commercial products.
Merton distinguishes two types of opinion leadership: monomorphic and polymorphic. Typically, opinion leadership is viewed as a monomorphic, domain-specific measure of individual differences, that is, a person that is an opinion leader in one field may be a follower in another field. An example of a monomorphic opinion leader in the field of computer technology, might be a neighborhood computer service technician. The technician has access to far more information on this topic than the average consumer and has the requisite background to understand the information, though the same person might be a follower at another field (for example sports) and ask others for advice. In contrast, polymorphic opinion leaders are able to influence others in a broad range of domains. Variants of polymorphic opinion leadership include market mavenism, personality strength  and generalized opinion leadership. So far, there is little consensus as to the degree these concepts operationalize the same or simply related constructs.
In his article "The Two Step Flow of Communication", Elihu Katz, found opinion leaders to have more influence on people's opinions, actions, and behaviors than the media. Opinion leaders are seen to have more influence than the media for a number of reasons. Opinion leaders are seen as trustworthy and non-purposive. People do not feel they are being tricked into thinking a certain way about something if they get information from someone they know. However, the media can be seen as forcing a concept on the public and therefore will be less influential. While the media can act as a reinforcing agent, opinion leaders have a more changing or determining role in an individual's opinion or action.
Factors for leadership
Opinion leaders are individuals who obtain more media coverage than others and are especially educated on a certain issue. They seek the acceptance of others and are especially motivated to enhance their social status. In the jargon of public relations, they are called thought leaders. Research has also found that opinion leaders tend to be boundary spanners.
In a strategic attempt to engage the public in environmental issues and his nonprofit, The Climate Project, Al Gore used the concept of opinion leaders. Gore found opinion leaders by recruiting individuals who were educated on environmental issues and saw themselves as influential in their community and amongst their friends and family. From there, he trained the opinion leaders on the information he wanted them to spread and enabled them to influence their communities. By using opinion leaders, Gore was able to educate and influence many Americans to take notice of climate change and change their actions.
Matthew Nisbet describes the use of opinion leaders as intermediaries between scientists and the public as a way to reach the public via trained individuals who are more closely engaged with their communities, such as "teachers, business leaders, attorneys, policymakers, neighborhood leaders, students, and media professionals." Examples of initiatives that take this approach include Science & Engineering Ambassadors, sponsored by the National Academy of Sciences, and Science Booster Clubs, coordinated by the National Center for Science Education.
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