USER INTERFACE DESIGN PROCESS

USER INTERFACE DESIGN PROCESS

1. Dialog Design and Representation

   • Diagrammatic notations
     • -State transition Diagram(STN). -Hierarchical state transition nets. -Concurrent dialogs and combinatorial explosion of states.
   • Textual dialog notations
     • -Grammars. -Production rules. -Communicating sequential processes and event algebras.

2. Error Handling and Help

   • Perceptual Errors
     • Result from poor perceptual cues -Display of objects that are visually similar -Invisible or poorly expressed states -Failure to capture user’s attention =Lack of perceivable feedback
   • Cognitive Errors
     • Taxing the motor skills -Awkward movements -Highly similar motor sequences e.g., double click, click -Pressure for speed -Require a high degree of hand-eye coordination -Requiring special types of motor skills (type)
   • Motor Errors
     • Caused by taxing memory and thinking -Tax recall memory -Poor mnemonic aids Inconsistency -Lack of context or status information e.g., where came from in a menu -Mental calculations and translations
   • Error
     • Mistakes (Conscious)
       •    Example:  If I don’t understand the system, then I may make mistakes.   
     • Slips (Automatics behaviors)
       •    Example: If I understand a system, but mistype or accidently press the mouse button at the wrong time, I’ve made a slip. I formulated the correct action but it was not executed correctly.   
       • Types of slips :
         • Capture error
         • Description error
         • Data driven error
         • Loss of activation
         • Mode errors
         • Association activation
   • Error Prevention Guidelines
     • Eliminate modes or provide visible cues for modes
     • Allow reconsideration of action by user (e.g. removing file from trash)
     • Maximize recognition, minimize recall
     • Provide appropriate type of feedback
     • Nothing - Just don’t do anything (Careful, user must determine problem)
     • Use good coding techniques (color, style)
     • Design non-similar motor sequences or commands
     • Minimize need for typing
     • Test and monitor for errors and engineer them out
     • Warn user an unusual situation is occurring
   • Error Recovery Guidelines
     • Responses Self-correct - Guess correct action & do it Spell-check correction Dialog - System opens dialog with user Go into debugger on run-time crash Query - Ask user what should’ve been done, then allow error action as legal one Command language naming error Provide undo function Provide cancel function from lengthy operations in progress Require confirmation for drastic, destructive commands Provide reasonableness checks on input data Did you really mean to order 5000? Return cursor to error field, allow fix Tell them what to fix, how to fix it Provide some intelligence Guess what they wanted to do Provide quick access to context-sensitive help
   • ERROR MESSAGE WORDING - VOCABULARY
   • ERROR MESSAGE WORDING - TONE