Mental model

  • an internal, simulatable understanding of external reality
    • design systems that act the way the user expects them to act
    • design systems that teach the user how they react
  • your goal is to teach the user how to use it WHILE they are using it
  • 5 tips
    • Predictability (gray button predictable that clicking wont work)
    • Syntesizability (see the sequence of actions that led to current state - hard! eg undo history)
    • Familiarity (similarity to other interface)
    • Generalizability (similarity)
    • Consistency (similar operations should be consistent in behavior eg cut n paste)

Representations

  • We get to choose how systems are visualized to users. Good relationships:
    • make relationships explicit
    • bring objects and relationships together
    • excludes extraneous details
    • expose natural constraints
  • metaphors and analogies
    • use something people have already seen
    • analogies make UI more learnable, but may constrain usage to outdated concepts
  • new funcitonality + old interfaces: learning curves are inevitable
    • rapid vs slow learning curves - chart analysis
  • slips and mistakes
    • slips: user has right model, but does the wrong thing anyway
      • action based slips - doing the wrong thing
      • memory lapse slips - forgets to do the right thing
    • mistakes: user doesnt even know right thing to do
      • rule based mistakes: correctly assesses state of the world, makes wrong decision
      • knowledge based: incorrectly assess the state of the wrodl
      • memory lapse: forgetting to fully execute a plan, not just forgetting what to do