Cognitive WalkthroughEvaluation method based on the idea that the user learns about the interface in an exploratory way,the user has goals,the user is applying simple means-ends reasoning.

Cognitive WalkthroughEvaluation by an expert, who goes through a set task while imitating user performance

Preparation: We need four thingsUser description including level of experience with computers and any assumptions made by the designerSystem description including operations and performance (e.g. paper design)Task description specifying the task that the expert has to carry out from users point of viewAction sequence describing the system display and the user actions needed to complete the given task. One system display and one user action together are one step.

Process of carrying out a Cognitive WalkthroughPrototype, user description, system description, task description and action list has to be prepared by the designer/developerDesigner gives these document to an expert.The expert reads the descriptions.The expert carries out the task by following the action list.The expert asks the following questions with EACH step of the action list:

Questions Cognitive WalkthroughIs the next goal clear at this stage?Is the appropriate action obvious?Is it clear that this action leads to the goal?What problems are there in performing the action?

Example: the Automatic Nail PainterThe automatic nail painter is a machine with which one can have ones nails painted.

User Description Automatic Nail PainterThe users are assumed to have no prior knowledge of how to operate the Automatic Nail Painter. However, they are assumed to have experience in putting nail varnish on nails manually

System Description Automatic Nail Painter The system allows one finger to be placed into the machine at a time. The user programmes the machine for use by choosing: - the number of fingers to be varnished - the colours of the varnish to be used - the number of coatings to be applied

Task Description Automatic Nail PainterThe user must get all ten fingers varnished with one coat of purple varnish. The system is already switched on when the user begins his/her task. The task is completed, when the tenth fingernail is varnished.

Action list Automatic Nail PainterSystem: System displays How many fingers do you want to varnish? User action: user selects number 10 by pressing the + or the - button until the appropriate number is shown System: System responds by displaying the current number of fingers selected to be varnished. User action: User presses ok when the correct number has been displayed

Action list Automatic Nail Painter (cont.)System: System displays choose the colour of varnish you wish to apply. User action: User must select the colour purple by choosing from the colour menu. This includes scrolling up and down until s/he finds purple. S/he then has to press the OK button. System: Systems displays how many coats do you want to apply? User action: User selects the number of coats by pressing the + or - button until the 1 is shown.

Action list Automatic Nail Painter (cont.)System: System displays the number of fingers to be varnished, the colour of the varnish and the number of coats to be applied. System asks for confirmation User action: User presses OK to confirm System: System displays Press start to begin varnishing. User action: User presses start button etc.

Step 1- Question 1 Automatic Nail PainterFrom the action list: Step 1 System: System displays How many fingers do you want to varnish? User action: user selects number 10 by pressing the + or the - button until the appropriate number is shownQuestion 1: Is the goal clear at this stage? Not completely. The user is asked to state the number of fingers to be varnished. He could be thinking that the system deals with one hand at a time.

Step 1 - Questions 2, 3, and 4Automatic Nail PainterQuestion 2: Is the appropriate action obvious? No. The system dos neither indicate that the user has to use the + and - buttons nor explain their use.Question 3: Is it clear that this action leads to the goal? Yes If the user presses the + and - button the numbers are clearly displayed.Question 4:What problems are there in performing the action? The action is simple to perform once the user has discovered the use of the buttons.

Step 2 Question 1Automatic Nailpainter?