在人機的互動中，操作介面為使用者與產品間之溝通橋樑，其設計良窳與否攸關產品使用性之高低；本研究以FUJIFILM公司所生產FinePix50i型「無中文化」介面之數位相機為對象，安排3個典型工作，檢測具數位相機操作經驗，但未曾使用過本廠牌數位相機之受測者，初次操作此數位相機介面操作之使用性問題；實驗進行採使用性評估之「回溯式測試(Retrospective Testing)法」，藉由與受測者共同回顧及討論錄影帶所記錄之內容，以探討數位相機操作介面之使用性問題及錯誤產生的原因，供日後進行數位相機操作系統或介面設計時之參考依據。根據研究結果發現，容易影響產品使用性問題發生之原因具有下列五項：1.使用者對產品操作之習慣模式。2.操作介面中具「方向指示性」之箭頭圖形「橫跨」不同功能介面時。3.操作介面之文字排列方式或區隔不當時。4.相同「圖像」介面造形於不同操作路徑之意義不一。5.具有相似目的之功能介面，其操作原理與方式不相同，以致於使用者無法藉由先前之學習經驗進行套用。

This research is regarded digital camera as the example, arrange three typical tasks, to examine who have digit cameras to operate experience but never use our factory's digital camera and observe those responders operating this digital camera will interface usability questions for the first time. The experiment is carried on the way of Retrospective Testing, with be reviewed and discussed the content written down to record the film video-tape together by the persons who examine, in order to probe into the reason why the usability question and mistake that the digital camera operates the interface produce, support the reference basis while carrying on the camera operating system of the digit or the interface design in the future. Find according to the result of study, apt to lead to the fact that the reason why the usability question of the products happens has the following five items: 1. Habit way that the user operates to the products. 2. Operate interface have arrow point figure "traverse" different function on 'direction instructive' when the interface. 3. The characters, which operated the interface, arranged the way or the district did not separate at that time. 4. The same the shaping of the interface differs in different meanings of operating the route for 'the picture'. 5. Have function interface of the similar purpose, however, it's operate principle and the mode do not the same way, causing on unable to apply mechanically by previous study experience user.