System Image

Map Branches

• Good design
  • Use Knowledge
    • In the world
      • In the head
    • Conceptual model
      • Designer's model
        • User's model
        • Intermediary
          • System Image
  • Structure of tasks
    • Simplify
    • Cognitive load
      • Reduce
  • Make things visible
    • Bring the gulfs
      • Of execution
      • Of evaluation
  • Mappings
    • Get'em right
  • Constraints
    • Exploit
  • Errors
    • Design for it
      • Recoverability
        • Unsafe actions
          • Difficult
  • Standardize
    • When all else fails
• Goals
  • Form Goal
    • Determine functions of device ?
      • In front of a device, how can the user...
    • Mistakes
      • Wrong goal
        • Poor plans
          • Incomplete knowledge
      • Aids
        • System model
          • Organization metaphors
            • Procedure hints
• Execution
  • Formulate Intention
    • Tell what actions are possible?
    • Mistakes
      • Wrong goal
        • Poor plans
          • Incomplete knowledge
      • Aids
        • Aid memoirs
          • Block unsafe actions
            • Clear controls
        • System simulation
          • Operational metaphors
  • Specify action
    • Map intentions to physical movements?
    • Mistakes
      • Wrong rules
        • Incorrect context
      • Aids
        • Device affordances
          • Prompts cues
    • Slips
      • Wrong procedure selected
      • Aids
        • Preselect safe actions
          • Difficult unsafe actions
  • Execute action
    • Perform the action?
    • Slips
      • Motor failures
        • Attention errors
          • Interruptions
      • Aids
        • Safety locks
          • Simplify manipulations
            • Fail safe
        • Prevent dangerous actions
          • Validate inputs
• Evaluation
  • Evaluate state
    • Mistakes
      • Aids
        • Update system models
          • Situation awareness
          • Show implications of change
      • Poor reasoning
        • Incomplete knowledge
    • Tell system state ?
  • Interpret state
    • Slips
      • Aids
        • Clear messages
          • Repeat warnings
      • Perceptual
    • Mistakes
      • Aids
        • Clear feedback
          • Set change in context
      • Poor reasoning
    • Map state to interpretation ?
  • Recognize effects
    • Error correction cycle
      • Execute corrective action
        • Action checklists
        • Highlight appropriate controls
        • Automatic correction
        • Clear corrective controls
      • Plan corrective action
        • Warn of side-off effects
        • List remedial procedures
      • Diagnose cause
        • Infer reasons
          • Assumption checks
        • List possible causes
          • Display failure history
      • Interpret problem
      • Recognize feedback
        • Show hazard effects
          • Show containment
        • Salient warnings
          • Locate hazard
    • Slips
      • Aids
        • Multimodal warning
          • Clear messages
            • Salient warnings
      • Distractions
        • Perceptual slips
    • Tell if system is in desired state ?

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