恐懼訴求是一個被政府與非營利組織廣泛運用以說服標的群體的策略，而如何有效設計恐懼訴求訊息，俾改變標的群體的態度、意圖與行為，則是一項長期受到重視的探討議題。因此，本文試圖從延伸平行過程模型（EPPM）的角度來探究戒菸計劃的成效。依據EPPM的觀點，恐懼訴求的成敗係由個體對於威脅事件的知覺威脅感及知覺效能感二者共同決定。基於此一考量，本研究探討標的群體如何與為何對運用恐懼訴求的戒菸計畫訊息會產生不同反應，今將主要研究發現綜述如下： 一、標的群體愈易於受到吸菸危害者，其所產生的知覺威脅感程度愈高。 二、使用非尼古丁戒菸藥物的標的群體，與使用尼古丁替代療法或意志力戒菸者相比，傾向具有更高的知覺效能感。 三、就威脅訊息的內容而言，年長者較關注自己的健康，而青少年則是較在意其他人對其吸菸之反應及香菸價格的高低。 四、個體差異對於知覺效能感的影響並不顯著。 本研究的結果顯示，受到威脅訊息而產生戒菸動機的標的群體，往往是因為缺乏效能感訊息而致戒菸失敗。因此，在設計戒菸宣導活動時，應將重點置於提供更多有關可用非尼古丁戒菸藥物的訊息，俾能提昇標的群體的知覺效能感。 Fear appeal is a widely used strategy for persuading target audiences in governmental and non-profit organizations. Therefore, how to effectively design fear appeal messages to change the attitudes, intentions, and behaviors of the target audience has long been an important issue to explore. This thesis attempts to investigate the effectiveness of smoking cessation programs from the perspective of the Extended Parallel Process Model (EPPM). According to the EPPM, the perceptions of threat and efficacy of individuals toward a threatening event will jointly determine the success or failure of fear appeals. For this reason, this research examines how and why target audiences respond differently to fear appeal messages in smoking cessation programs. The major research findings are summarized below: First, individuals who are highly susceptible to the harm of smoking tend to have greater levels of perceived threat. Second, individuals using non-nicotine smoking cessation drugs have greater levels of perceived efficacy than people using nicotine replacement therapy or willpower to quit smoking. Third, for threat messages, older people are more concerned about their health whereas the youths are more concerned about other people''s reactions and the price of cigarettes. Last, individual differences do not have significant effects on perceived efficacy. The findings of this research indicate that individuals motivated to quit smoking by threat messages often fail as a result of lack of efficacy messages. Therefore, designing smoking cessation campaigns should put more emphasis on providing efficacy messages about available non-nicotine smoking cessation drugs to increase the perceived efficacy of the target audience.