1Fall 2005 6.831 UI Design and Implementation 1 Fall 2005 6.831 UI Design and Implementation 2 Plenty to choose from Nielsen s 10 principles One version in his book A more recent version on his website Tognazzini s 16 principles Norman s rules from Design of Everyday Things Mac, Windows, Gnome, KDE guidelines Help designers choose design alternatives Help evaluators find problems in interfaces (heuristic evaluation)Fall 2005 6.831 UI Design and Implementation 3 User-centered design Know your users Understand their tasks Fitts s Law Size and proximity of controls should relate to their importance Tiny controls are hard to hit Screen edges are precious Memory Use chunking to simplify information presentation Minimize working memory Color guidelines Don t depend solely on color distinctions (color blindness) Avoid red on blue text (chromatic aberration) Avoid small blue details Norman s principles of direct manipulation Affordances Natural mapping Visibility FeedbackFall 2005 6.831 UI Design and Implementation 4!"# $$%& Use common words, not techie jargon But use domain-specific terms where appropriate Don t put limits on user-defined names Allow aliases/synonyms in command languages Metaphors are useful but may misleadSource: Interface Hall of Shame2Fall 2005 6.831 UI Design and Implementation 5'"( ) Principle of Least Surprise Similar things should look and act similar Different things should look different Other properties Size, location, color, wording, ordering, Command/argument order Prefix vs. postfix Follow platform standardsSource: Interface Hall of ShameFall 2005 6.831 UI Design and Implementation 6*+( Internal External MetaphoricalFall 2005 6.831 UI Design and Implementation 7(,( Inconsistency is appropriate when context and task demand it Arrow keys But if all else is (almost) equal, consistency wins QWERTY vs. Dvorak OK/Cancel button orderFall 2005 6.831 UI Design and Implementation 8-" Users don t read manuals Prefer to spend time working toward their task goals, not learning about your system But manuals and online help are vital Usually when user is frustrated or in crisis Help should be: Searchable Context-sensitive Task-oriented Concrete Short3Fall 2005 6.831 UI Design and Implementation 9."( Provide undo Long operations should be cancelable All dialogs should have a cancel button User-provided data should be editableSource: Interface Hall of ShameFall 2005 6.831 UI Design and Implementation 10/"0+) ) 1 Keep user informed of system state Cursor change Selection highlight Status bar Don t overdo it Response time < 0.1 s: seems instantaneous 0.1-1 s: user notices, but no feedback needed 1-5 s: display busy cursor > 1-5 s: display progress barSource: Interface Hall of ShameFall 2005 6.831 UI Design and Implementation 11/"0+) ) 1Fall 2005 6.831 UI Design and Implementation 122"3 ++ )$ Provide easily-learned shortcuts for frequent operations Keyboard accelerators Command abbreviations Styles Bookmarks HistorySource: Interface Hall of Shame4Fall 2005 6.831 UI Design and Implementation 134" 5 Selection is less error-prone than typing But don t go overboard Disable illegal commands Keep dangerous commands away from common onesSource: Interface Hall of ShameFall 2005 6.831 UI Design and Implementation 14 Intended action is replaced by another action with many features in common Pouring orange juice into your cereal Putting the wrong lid on a bowl Throwing shirt into toilet instead of hamper Going to Kendall Square instead of Kenmore Square Avoid actions with very similar descriptions Long rows of identical switches Adjacent menu items that look similarFall 2005 6.831 UI Design and Implementation 15( A sequence of actions is replaced by another sequence that starts the same way Leave your house and find yourself walking to school instead of where you meant to go Vi :wq command Avoid habitual action sequences with common prefixesFall 2005 6.831 UI Design and Implementation 16# Modes: states in which actions have different meanings Vi s insert mode vs. command mode Caps Lock Drawing palette Avoiding mode errors Eliminate modes Visibility of mode Spring-loaded or temporary modes Disjoint action sets in different modes5Fall 2005 6.831 UI Design and Implementation 17# # Fall 2005 6.831 UI Design and Implementation 18"% 67% # Use menus, not command languages Use combo boxes, not textboxes Use generic commands where possible (Open, Save, Copy Paste) All needed information should be visibleSource: Interface Hall of ShameFall 2005 6.831 UI Design and Implementation 198" %66% 5 Be precise; restate user s input Not Cannot open file, but Cannot open file named paper.doc Give constructive help why error occurred and how to fix it Be polite and nonblaming Not fatal error, not illegal Hide
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