Extended Cognitive Walkthrough

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Extended Cognitive Walkthrough

• Judy Kay
• CHAI Computer human adapted interaction research
  group
• School of Information Technologies

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Overview

• Predictive methods
• Cognitive Walkthrough
• Benefits
• Disadvantages
• (gt45,000 Google matches)?

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Postconditions for this week (incl studio)?

• Describe the uses of Cognitive Walkthrough
• Describe the processes for conducting Cognitive
  Walkthrough analyses
• Describe advantages and limitations
• Ability to perform a Cognitive Walkthrough study
• Justify the use of Cognitive Walkthrough in the
  overall testing of a pervasive computing
  application

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• Focus on learnability
• Appropriate for novice or casual users
• Does not focus on speed
• Sequence is not known prior to inspection
• Assesses user success and recovery from errors
• Conducted by experts (similar to ...)?

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Model of Exploratory Learning

• User has task
• 0. will user understand this sub-task is needed
• Explores system for useful elements
• 1. will correct action be obvious? eg button
  visible
• 2. will user understand instructions? eg user
  understands the label on the button
• Selects one to try
• User interprets system response
• 3. will user know if progress has been made?

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• User has task
• 0. will user understand this sub-task is needed
  (given their mental model)?
• Explores system for useful elements
• 1. will correct action be obvious?
• (given their mental model)?
• 2. will user understand instructions?
• (given their mental model)?
• Selects one to try
• User interprets system response
• 3. will user know if progress has been made?
• (given their mental model)?

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Example (Adapted from Newman and Lamming)?

• Design a cash-operated machine for quick, easy
  purchase of train tickets by passengers
• Determine fare to pay
• indicate destination
• indicate one-way or return
• Dispense ticket
• pay money
• get ticket and change

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The interface
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The task

• buy a one-way ticket to Town Hall

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• 0. Task?
• Buy one-way ticket to Town Hall
• 1. Is correct action obvious?
• Two possibilities
• Destination
• One way / return
• Will user know both must
• be set?

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• How to Help the User?
• Indicate extra information needed
• Indicate steps 1 and 2 can be done in either
  order
• Reorganise layout so that Steps 1 and 2 display
  fare

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• 2. Will user understand instructions?
• 3. Will user interpret machine action correctly?

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• 2. Will user understand instructions?
• Yes due to labels and instructions
• 3. Will user interpret machine action correctly?
• Yes (buttons light up, new state appears)?

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• Correct action obvious?
• 2. Will user understand instructions?
• 3. Will user interpret machine action correctly?

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• Correct action obvious?
• Yes
• 2. Will user understand instructions?
• Yes
• 3. Will user interpret machine action correctly?
• Yes

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Paying

• 1. Correct action obvious?
• 2. Will user understand instructions?
• 3. Will user interpret machine action correctly?

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Paying

• 1. Correct action obvious?
• Yes
• 2. Will user understand instructions?
• Yes
• 3. Will user interpret machine action correctly?
• Unclear (no feedback on money accepted so far)?

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(No Transcript)
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Buying a Ticket Insufficient Money?

• 1. Correct action obvious?

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Summary of Flaws (so far)?

• Confusion about need for steps 1 and 2
• No feedback on amount deposited
• No means to get money back
• (Haven't yet assessed fare type option)?
• (Goals and subgoals
• Sub-goals (fare-determination vs ticket
  dispensing)?
• Are all sub-goals needed (no - we might know the
  fare)?

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Extended cognitive walkthrough

• Adding user's mental model
• What does user believe?
• How do you find this out?

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Summary of uses

• Relatively inexpensive
• Desk check
• No users
• Better with expert evaluators
• Generally applicable
• Novice, casual, intermittent users
• Focus on learnability
• Relevance for Pervasive?