Extended Cognitive Walkthrough Judy Kay CHAI: Computer human adapted interaction research group School of Information Technologies

HAI2008. Lifelong ambient companions: challenges and steps to overcome them Overview Predictive methods Cognitive Walkthrough Benefits Disadvantages (>45,000 Google matches)‏

HAI2008. Lifelong ambient companions: challenges and steps to overcome them 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

HAI2008. Lifelong ambient companions: challenges and steps to overcome them 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...)‏

HAI2008. Lifelong ambient companions: challenges and steps to overcome them 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?

HAI2008. Lifelong ambient companions: challenges and steps to overcome them 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)‏

HAI2008. Lifelong ambient companions: challenges and steps to overcome them 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

HAI2008. Lifelong ambient companions: challenges and steps to overcome them The interface

HAI2008. Lifelong ambient companions: challenges and steps to overcome them The task buy a one-way ticket to Town Hall

HAI2008. Lifelong ambient companions: challenges and steps to overcome them 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?

HAI2008. Lifelong ambient companions: challenges and steps to overcome them 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

HAI2008. Lifelong ambient companions: challenges and steps to overcome them 2. Will user understand instructions? 3. Will user interpret machine action correctly?

HAI2008. Lifelong ambient companions: challenges and steps to overcome them 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)‏

HAI2008. Lifelong ambient companions: challenges and steps to overcome them Correct action obvious? 2. Will user understand instructions? 3. Will user interpret machine action correctly?

HAI2008. Lifelong ambient companions: challenges and steps to overcome them Correct action obvious? –Yes 2. Will user understand instructions? –Yes 3. Will user interpret machine action correctly? –Yes

HAI2008. Lifelong ambient companions: challenges and steps to overcome them Paying 1. Correct action obvious? 2. Will user understand instructions? 3. Will user interpret machine action correctly?

HAI2008. Lifelong ambient companions: challenges and steps to overcome them 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)‏

HAI2008. Lifelong ambient companions: challenges and steps to overcome them

HAI2008. Lifelong ambient companions: challenges and steps to overcome them Buying a Ticket: Insufficient Money? 1. Correct action obvious?

HAI2008. Lifelong ambient companions: challenges and steps to overcome them 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)‏

HAI2008. Lifelong ambient companions: challenges and steps to overcome them Extended cognitive walkthrough Adding user's mental model What does user believe? How do you find this out?

HAI2008. Lifelong ambient companions: challenges and steps to overcome them 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?