認知心理學之構念啟動與使用模式指出，構念若因外界重複刺激而長期被啟用後，可對相關評估產生長時性影響。本研究認為，媒介框架在具備強度與即時性時，可能重複啟動受眾知識倉儲相關構念，並因此發揮長期預設判準效應。本研究以核四案為例，探討預設判準效應（priming）與框架（framing）二項媒介作用的相關性，以及媒介框架在個人層次的運作機制與效應。內容分析與受眾調查分析顯示，核四案報導中，媒介主要框架同時具備強度與即時性，符合產生長期效果條件，且受眾是否採用媒介主要框架也顯著預測其核四政策立場。這說明媒介報導一議題時，跨時期使用的主要框架，可對閱聽人相關政策的評估產生長期預設判準效應。另外，核四主要框架的採用也是看核四新聞頻率與核四立場的中介變項。受眾看愈多核四相關新聞，愈易採用媒介主要框架認知核四，也因而愈傾向贊成續建。這指出，媒介主要框架所隱含的擁核立場可影響民意，主流新聞媒體是一替民進黨政府反核四政策「去正當化」（delegitimizing）的重要機構。

　　　　　The model of construct activation and use from cognitive psychology states that when particular constructs become subject to routine activation and use due to consistent stimuli over time, long-term effects may be expected. This study proposes that when media frames are both intensive and recent, they are likely to repetitively activate related constructs in audience members?knowledge store and then develop into long-term priming effects. Using the Fourth Nuclear Power Plant dispute as a test case, this study examines the relationship between two media functions, priming and framing, and the operative mechanisms of media framing effects on the individual level. Results of content analysis and an audience survey show that the primary media frames were indeed intensive and recent, and that the adoption of primary media frames significantly predicted audience members’ policy stances. This suggests that consistent media frames over time have long-term priming effects on audience members?policy evaluations. Furthermore, the adoption of primary media frames serves as a mediator between exposure to case-related news and policy stances. The more the audience members were exposed to case-related news, the more likely they would be to adopt the primary media frames and support the construction of the Fourth Nuclear Power Plant. This implies that the pro-nuclear stance of the primary media frames affected public opinion, and that the news media were conducive to delegitimizing the DPP's anti-Fourth Nuclear Power Plant policy.