在購買意願的影響因素中，除了消費者所具備的產品知識外，品牌也成爲一個備受矚目的指標。亦即，消費者在缺乏產品知識的情形下，將會依賴產品所提供的線索與自身的心理認知來進行購買行爲，此時產品的品牌形象會在購買决策上扮演相當重要的角色。過去學者對品牌效果的研究，多利用產品外顯線索提供的資訊，來探討消費者的購買意願。爲求探討更合理的消費者購買行爲影響因素，本研究藉由產品內在線索－消費者的產品知識與外在線索－品牌形象，來分別研究產品知識與品牌形象對購買意願的影響是否會受到產品類別的干擾。本研究針對某私立大學的學生進行問卷調查。在選擇受測產品時，根據相關文獻選擇4種績效不易客觀衡量的產品作前測，從中選擇各一種類別（便利品、特別品）的產品。正式實驗則爲一2(上標 *)2(上標 *)2的實驗組合。本研究得到下列研究結果：1.消費者所擁有產品知識程度愈高時，消費者的購買意願愈高。2.產品的品牌形象愈高，消費者的購買意願愈高。3.與便利品比較，特別品在高產品知識下有較高的購買意願。4.與便利品比較，特別品在高品牌形象下有較高的購買意願；與便利品比較，特別品在低品牌形象下有較低的購買意願。

When lacking of related product knowledge, consumers would depend on the clues offered by the product and the self-perceptions to do purchasing. In the past, most of the research regarding brand effects used only extrinsic clues to explore the consumers' purchase intention. To discuss more reasonable factors, the study examines the impact of product knowledge (intrinsic clue) and brand image (extrinsic clue) on purchase intention, moderated by product categories. By a 2(superscript *)2(superscript *)2 experimental design, we found that: 1. The higher the product knowledge the consumers have, the higher the purchase intention. 2. The better the brand image is, the higher the purchase intention. 3. In high product knowledge, consumers have higher purchase intention in specialty goods than convenience goods. 4. In high brand image, consumers have higher purchase intention in specialty goods than convenience goods; In low brand image, consumers have lower purchase intention in specialty goods than convenience goods.