1. COMP5047 Pervasive Computing: 2012 Extended Cognitive Walkthrough Judy Kay CHAI: Computer human adapted interaction research group School of Information Technologies

2. COMP5047 Pervasive Computing: 2012 2 Overview Predictive method Cognitive Walkthrough Benefits Disadvantages (About 446,000 results from Googl)‏

3. COMP5047 Pervasive Computing: 2012 3 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

4. COMP5047 Pervasive Computing: 2012 4 Focus on learnability Appropriate for novice or casual users cf Think-Aloud? Does not focus on speed cf Think-Aloud? Sequence is not known prior to inspection Assesses user success and recovery from errors Conducted by experts cf Think-Aloud?

5. COMP5047 Pervasive Computing: 2012 5 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?

6. COMP5047 Pervasive Computing: 2012 6 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)‏

7. COMP5047 Pervasive Computing: 2012 7 Example 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 Adapted from Newman and Lamming, Interactive System Design, 1995 )‏

8. COMP5047 Pervasive Computing: 2012 8 The interface

9. COMP5047 Pervasive Computing: 2012 9 The task buy a one-way ticket to Town Hall

10. COMP5047 Pervasive Computing: 2012 10 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?

11. COMP5047 Pervasive Computing: 2012 11 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

12. COMP5047 Pervasive Computing: 2012 12 2. Will user understand instructions? 3. Will user interpret machine action correctly?

13. COMP5047 Pervasive Computing: 2012 13 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)‏

14. COMP5047 Pervasive Computing: 2012 14 Correct action obvious? 2. Will user understand instructions? 3. Will user interpret machine action correctly?

15. COMP5047 Pervasive Computing: 2012 15 Correct action obvious? –Yes 2. Will user understand instructions? –Yes 3. Will user interpret machine action correctly? –Yes

16. COMP5047 Pervasive Computing: 2012 16 Paying 1. Correct action obvious? 2. Will user understand instructions? 3. Will user interpret machine action correctly?

17. COMP5047 Pervasive Computing: 2012 17 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)‏

18. COMP5047 Pervasive Computing: 2012 18

19. COMP5047 Pervasive Computing: 2012 19 Buying a Ticket: Insufficient Money? 1. Correct action obvious?

20. COMP5047 Pervasive Computing: 2012 20 Summary of Flaws (so far)‏ Confusion about need for steps 1 and 2 No feedback on amount deposited No means to get money back So far …...

21. COMP5047 Pervasive Computing: 2012 21 Goals and Tasks In this example: Goal: buy a ticket Sub-goals: (determine fare) and pay User tasks: concrete cases used in CW

22. COMP5047 Pervasive Computing: 2012 22 Extended cognitive walkthrough Adding user's mental model What does user believe? How do you find this out?

23. COMP5047 Pervasive Computing: 2012 23 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?

24. COMP5047 Pervasive Computing: 2012 24 Summary Really useful technique, even for designer Better if done by Outsider Expert Part of early usability evaluation because Low cost No users needed