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Heuristics usability evaluation [要訣式易用性評估]

heuristics 取意自 heuristics reasoning: 捷徑推理:

捷徑式推理是在問題情境中,大多數人還是不知道邏輯推論法則,因此他們不能在需要時使用運作這些法則,因此人們使用某些方法來克服這種形式知識的不足。而人們往往根據以往解決類似問題的經驗所累積的訣竅去推理解決問題的方法,其最大特徵是不按邏輯程序去思考,不按常理去看問題,在時間有限的情境下,由極具經驗的人使用,有時可收事半功倍之效,但結果卻未必保證成功,如賭徒謬誤(gambler’s fallacy)。捷徑式推理是遵循經驗法則(rule of experience)運作的(張春興,1992)。

heuristics usability evaluation 並非實徵的使用性評估,而依賴於專家根據某些已驗證過的經驗法則進行評估。

翻譯問題

坊間常見的譯法「啟發性評估」,並沒有傳達出原本採取這一種加快認知判斷的捷徑,兼有正面與負面的意涵。然而,目前在中文世界中,並沒有普遍公定的正確譯法。

若,也可以採取語用取徑考慮翻譯的問題。在使用性研究的領域中,Heuristics 在語用上很接近準則、標準或檢核表(guideline, criteria, checklist),或是藉此進行使用性評估的方法(heuristics evaluation)。而使用性隨著「使用經驗設計」領域的擴張,heuristic作為檢驗規範的用法也擴張到其他相關主題上,如可玩性、可社會性等等。

[2011-Oct-1]: 或可譯為「訣竅/竅門」? [2013-Feb-7]: 意思上比較像「心訣」,指一種加快認知判斷的捷徑,兼有正面與負面的意涵。若依照語用,在使用性研究的領域中,很接近準則或檢核表。)

  • Nielsen 使用性檢核規範的發展:最早是根據個人經驗所建立的檢查清單[1][2]。之後根據七組不同檢核規範的內容進行因素分析,重新歸納為九種[3],後來又增加一種為十種[4]。
    [1] Molich, R. & Nielsen, J.. Improving a human-computer dialogue. Communications of the ACM, 33, 3, (1990) 338-348
    [2] Nielsen, J., and Molich, R. Heuristic evaluation of user interfaces. In Proc. CHI'90, ACM (1990), 249-256
    [3] Nielsen, J. Enhancing the explanatory power of usability heuristics. In Proc. CHI 1994, ACM (1994), 152-158
    [4] Nielsen, J. Heuristic evaluation. In Nielsen, J., & Mack, R. L. (Eds.), Usability inspection methods. John Wiley & Sons (1994), 25-62
  • [22] Scapin, D.L. and Bastien, J.M.C. Ergonomic criteria for evaluating the ergonomic quality of interactive systems. In Behaviour & Information Technology, 6, 4-5 (1997), 220-231

Nielsen 10

Jakob Nielsen 建立的訣竅使用性評估十要點:

  • 狀態可視性 Visibility of system status
    系統必須告知使用者將前往何處,並在合理的時間內給予適當的回饋
    The system should always keep users informed about what is going on, through appropriate feedback within reasonable time.
  • 符合自然世界秩序 Match between system and the real world
    系統須符合自然世界的邏輯,與使用者熟悉的語言,而非系統導向的語言 The system should speak the users' language, with words, phrases and concepts familiar to the user, rather than system-oriented terms. Follow real-world conventions, making information appear in a natural and logical order.
  • 有控制的自由: 使用者可隨時退回或離開 User control and freedom
    Users often choose system functions by mistake and will need a clearly marked “emergency exit” to leave the unwanted state without having to go through an extended dialogue. Support undo and redo.
  • 一致與標準 Consistency and standards
    Users should not have to wonder whether different words, situations, or actions mean the same thing. Follow platform conventions.
  • 預防錯誤 Error prevention
    預防錯誤比提供良好的錯誤訊息更重要。 Even better than good error messages is a careful design which prevents a problem from occurring in the first place. Either eliminate error-prone conditions or check for them and present users with a confirmation option before they commit to the action.
  • 認得勝過於記得 Recognition rather than recall
    Minimize the user's memory load by making objects, actions, and options visible. The user should not have to remember information from one part of the dialogue to another. Instructions for use of the system should be visible or easily retrievable whenever appropriate.
  • 彈性與效率 Flexibility and efficiency of use
    Accelerators – unseen by the novice user – may often speed up the interaction for the expert user such that the system can cater to both inexperienced and experienced users. Allow users to tailor frequent actions.
  • 兼具美感與極簡的設計 Aesthetic and minimalist design
    Dialogues should not contain information which is irrelevant or rarely needed. Every extra unit of information in a dialogue competes with the relevant units of information and diminishes their relative visibility.
  • 協助使用者處理錯誤 Help users recognize, diagnose, and recover from errors
    Error messages should be expressed in plain language (no codes), precisely indicate the problem, and constructively suggest a solution.
  • 協助與文件 Help and documentation
    Even though it is better if the system can be used without documentation, it may be necessary to provide help and documentation. Any such information should be easy to search, focused on the user's task, list concrete steps to be carried out, and not be too large.

Gerhardt 根據認知原則的使用性檢核表

Jill Gerhardt-Powals: cognitive principles for enhancing computer performance

非常地認知導向。這份真的很「啟發」了,一般設計師在設計上較難實用,需要有較好的認知科學基礎。此外還有缺點,有些準則寫的是目的(ends),有的是手段(means),導致有幾條似乎互相重複。如減少心智計算vs融合資料。有些很模糊,準則或是檢核表內不應該有「appropriate」「judicious redundancy」這類描述,若知道什麼是「適當、判斷正確」那還需要參考準則嗎?

  • 自動化不必要的工作負荷 Automate unwanted workload:
    • 將認知資源運用在高階的任務上 free cognitive resources for high-level tasks.
    • 減少心智計算、權衡與比較 eliminate mental calculations, estimations, comparisons, and unnecessary thinking.
  • 降低不確定性 Reduce uncertainty:
    • 資料呈現應清楚明顯 display data in a manner that is clear and obvious.
  • 融合資料 Fuse data:
    • 將低階資料總結為較高階的摘要,以降低認知負荷 reduce cognitive load by bringing together lower level data into a higher-level summation.
  • 新資訊應有意義地的呈現,以助於理解 Present new information with meaningful aids to interpretation:
    • 利用熟悉的框架 use a familiar framework, making it easier to absorb.
    • 利用日常的詞彙、隱喻 use everyday terms, metaphors, etc.
  • 使用與功能相關的名稱 Use names that are conceptually related to function:
    • 與脈絡有關的 Context-dependent.
    • 有助於記憶與辨識 Attempt to improve recall and recognition.
    • 用一致性且有意義的方式群組資料,以節省搜尋時間 Group data in consistently meaningful ways to decrease search time.
  • 限制資料型任務 Limit data-driven tasks:
    • 減少吸收原始資料的時間 Reduce the time spent assimilating raw data.
    • 使用適當的顏色與圖形 Make appropriate use of color and graphics.
  • 每次只呈現需要的資訊 Include in the displays only that information needed by the user at a given time.
    • 適當時提供資料多重的面相 Provide multiple coding of data when appropriate.
    • 練習正當的節約 Practice judicious redundancy.

比較特定領域中,使用性檢核表評估與使用性測試研究

Dykstra, D. J. A Comparison of Heuristic Evaluation and Usability Testing: The Efficacy of a Domain-Specific Heuristic Checklist. Ph.D. diss., Department of Industrial Engineering, Texas A&M University, College Station, TX, (1993)

References