使用字典輔助閱讀為一項能解決學習者本身字彙量限制及文章脈絡線索等問題的有效方法。本研究目的為探討學習者使用電腦字典對於非刻意字彙習得(incidental vocabulary acquisition)的影響。將27位大學生隨機分配至實驗的三個組別:無提供字典之控制組(no-aid)、不同輸入模式字典之「點選型字典組」(click-on dictionary)及「輸入型字典組」(key-in dictionary)。透過眼動儀記錄學習者使用電腦字典閱讀的目標字查詢及字義搜尋歷程,以認知負荷的角度搭配字彙習得表現,探討認知歷程中對於學習者習得字彙是益處還是阻礙。本研究結果為:1.「有使用字典組」在目標字凝視平均時間顯著多於「無使用字典組」,但兩組在字彙習得表現,以及學習者感知文章內容與字彙之困難程度皆未達顯著差異。2.「輸入型字典組」在拼字測驗、目標字平均查詢時間、目標字平均凝視時間及學習者感知使用字典的困難程度皆顯著多於「點選型字典組」,增加的負荷為有助於認識字彙拼法之增生負荷。3.「輸入型字典組」在字典與文章遞移的平均次數及投入於找尋對的字義之心力顯著多「點選型字典組」,兩組在字義配對測驗表現、字典內容平均凝視時間與心力皆未達顯著差異。當「輸入型字典組」在目標字查詢歷程花費太多的時間查詢時,暫存於工作記憶中的文章內容及脈絡產生中斷,而在獲得字典內容後,則須補足對於文章內容的理解。根據本研究結果建議,以供實務及後續研究參考。To second language learners, using dictionary while reading helps them to solve the context clues mysteries and the problem of lack of vocabulary. The aim of this study is to explore the effect of computer-mediated dictionaries on incidental vocabulary acquisition.Twenty-seven college students were randomly assigned to three conditions: (1) no-aid (control), (2) click-on dictionary, and (3) key-in dictionary.The processes of headword finding and meaning finding were recorded using eye tracking. From the perspective of cognitive load and the learning performance of vocabulary, we explored if using a dictionary was beneficial or a hindrance to learners’ vocabulary acquisition. The results of this study were as follows: 1.The two groups which had dictionaries spent significantly more time on target words than the group without any aid. But the groups with and without dictionaries had no significant difference in the performance of vocabulary acquisition, and in the self-reported degree of difficulty of the article content and vocabulary.2.In the process of headword finding, the key-in group spent significantly more time than the click-on group on the spelling test, the average search time of target words, and the average fixation duration of target words. The key-in group also had significantly more self-reported degree of difficulty of dictionary use than click-on group. The increased cognitive load is called germane cognitive load, and it brought benefit to the spelling test for the key-in group.3.In the process of meaning finding, the key-in group had significantly more average number of transitions between the dictionary and the article, and paid more effort to find the suitable meaning. But the two groups had no significant difference in the performance of vocabulary meaning test, and in the fixation duration and effort spent on the dictionary content. Key-in group spent too much time on headword finding, and thus it caused to interrupt the process of storing the contents of the article in working memory, so the comprehension of the article needed to be complemented by the content of the dictionary after looking up words. Based on these results, this study can provide reference for practice and future researches.