Human Capabilities: Mental Models

1
Human CapabilitiesMental Models

• CS352

2
Announcements

• Notice upcoming due dates (web page).
• Where we are in PRICPE
• Predispositions Did this in Project Proposal.
• RI Research is in process (studying users), due
  Friday. Should lead to Insights.
• CP Concept and initial (very low-fi) Prototypes
  due soon (see schedule).
• Evaluate throughout, repeat iteratively!!

3
Hints Team Process Improvement

• List risks and what youll do if they
  materialize.
• Agree on a process for working out disagreements
  in direction.
• We should use a web interface! No, we should use
  portable bar-code readers!
• eg votes? eg quality data from CogTool? eg
  joint visits to office hours?
• Do a post-mortem after every hand-in or grade
  received
• What went right in our process?
• Data, not finger-pointing we got an A-.
• What went wrong in our process?
• Data, not finger-pointing we had to pull an
  all-nighter because we started too late
• What will we do differently from now on?
• Write it down and revisit next time.

4
Mental Models

• How to use the system (and how the system
  works).
• Users build these in their heads.
• Developed over time.
• Why do users build these?
• Rote mem is hard, explained-by memory easier.
• Mental model is an explanation.
• If users mental model is correct, will have an
  easier time using the system.
• Not always correct (and usually not complete).
• Thermostat example.

5
How to help users mental model be correct

• Remember Normans 2 Gulfs?
• Gulf of Evaluation, Gulf of Execution
• We can use them to understand how to help
• Useful feedback in response to inputs
  (Evaluation).
• Ways of interacting with UI consistent with
  underlying workings (EvalExec).
• Context-sensitive devices for guidance
  (Execution).

6
Activity Thermostat

• Sketch a thermostat UI idea that does 1, 2, or 3.

7
How people do thingsthe 7 stages of an action

• Norman, at a conf in Italy.
• Speaker needed to show film, ad trouble threading
  it into projector.
• Many people came up to help, none succeeded.
• Finally technical was called, who quickly
  threaded it correctly.
• Q Why so hard?
• A Structure of an action as relate to the Gulfs.

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The 7 stages

• 1goal. 2,3,4execution. 5,6,7evaluation.
• (drawing)

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The 7 stages (cont)

• 1. goal what we want to do.
• Example.

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The 7 stages (cont)

• 2. execution intention (from what to how but
  top-level without details)
• Example.
• 3. execution sequence of actions.
• Example.
• 4. execution physically do them.
• Example.

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The 7 stages (cont.)

• 5. evaluation perceiving (senses) what the world
  did in response (with our eyes, etc.)
• Example.
• 6. evaluation interpreting (brain) the
  perception.
• Example.
• 7. evaluation comparison of interpretation with
  goal.
• Example.

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The 7 stages (cont.)

• Gulf of Execution.
• How to get from 1 to 2, 2 to 3, or 3 to 4.
• Example.
• Gulf of Evaluation.
• How to get to 5 at all, 5 to 6, 6 to 7.
• Example.

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The 7 stages as design aids

• To find problems, apply these to any task in a
  UIHow easily can determine ...
• 1. Goal ...the purpose of the device/feature?
• 2. Exec ... what actions are possible?
• 3. Exec ...the mapping from intention to
  specific physical movements?
• 4. Exec ...how to actually perform the action?
• 5. Eval ...what state the system is in?
• 6. Eval ...what that (feedback in UI) means?
• 7. Eval if system is in desired state?

14
Activity

• In pairs (cell phone owner, other)
• Cell phone owner drives (no thinking, just hit
  keys when told to).
• Other thinks (no access, just tell driver what
  to do).
• Task
• Make ALL display dimming go away. It should never
  dim at all under any circumstances.
• Ask the 7 questions at each stage.

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To find solutions

• Consider these remedies.
• Visibility to reveal
• state (5),
• show what actions available (2).
• Good mappings revealing
• relationships between actions and results (2),
• controls and effects (3),
• system state and what is visible (6, 7)
• Feedback
• every action provides immediate feedback of
  results (5,6,7)