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Miller and Krosnick: News media impact on the ingredients of presidential evaluations

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Miller and Krosnick. 2000. News media impact on the ingredients of presidential evaluations. AJPS.

The Lit's Problem

The lit has (correctly) found priming effects: If the media covers an issue, then people evaluate politicians largely in terms of that issue. But the lit has incorrectly attributed this to "accessibility" effects. The real cause is "agenda setting," moderated by trust and political knowledge.


  • Mediators: The causal mechanism by which priming occurs ("accesibility" vs "agenda setting").
  • Moderators: Factors upon which mediators depend/interact in order to have their effect (trust and political knowledge).
  • Accessibility: Priming works by bringing certain considerations to the top of your mind.
  • Agenda setting: Priming works b/c prominent news coverage serves as a cue to viewers that informed people (news editors) consider the issue imporant--and therefore, voters infer that the issue must be important, and act accordingly.
  • Trust: If you trust the media, you are more likely to follow its agenda-setting cues.
  • Political knowledge: Those with more knowledge are more easily able to understand the story and its significance and to recall the story later. Knowledge only matters if you already trust the media.

The Model

  • News coverage --> Trust in media --> Knowledge --> Agenda-setting inference, thus priming
  • The agenda-setting variable interacts with both trust and knowledge. All three interact together to determine how strong the priming effect of news coverage is. The degree of priming depends on your knowledge, which only matters if you trust the media.

The Design

Experimental. Subjects view various news broadcasts, some of which have prominent stories about particular subjects included. (i.e. all viewers watched the same base set of stories, but some had stories about drugs, immigration, or crime inserted into their video.) Then they evaluate Clinton (both generally and in terms of the policy at hand).

  • If accessibility was the mechanism, then people who saw the additional topics should make evaluations about those topics more quickly. They don't.