1. John Kelleher (IT Sligo) Cognitive Walkthrough

2. 1 Background Authors – Lewis & Polson (1991) Based on theory L&P CE+ Theory of Exploratory Learning Assesses the usability of a system in situations where the user is not an expert May be attempting a task that he or she has never done before. Conducted by evaluator, not users

3. 2 Behaviour Model 1. The user sets a goal to be accomplished with the system. A typical goal will be expressed in terms of the expected capabilities of the system, such as "check spelling of this document". 2. The user searches the interface for currently available actions. The availability of actions may be observable as the presence of menu items, of buttons, of available command-line inputs, etc. 3. The user selects the action that seems likely to make progress toward the goal. 4. The user performs the selected action and evaluates the system’s feedback for evidence that progress is being made toward the current goal.

4. 3 Evaluation Procedure Manual simulation of a user iteratively carrying out the stages of the behaviour model. A general description of the type of users who are expected to use the system, and the relevant knowledge that these users would be expected to have. A description of one or more representative tasks to be used in the evaluation. For each of the tasks, a list of the correct actions that should be performed in order to complete the task.

5. 4 Evaluation Procedure (contd.) Evaluator(s) consider interface at each step of task Examine interface & tell a story why the user would choose that action These stories then evaluated: 1. consider what the user’s current goal is; 2. evaluate the accessibility of the correct control; 3. evaluate the quality of the match between the control’s label and the goal; and 4. evaluate the feedback provided after action.

6. 5 Advantages of CW Focuses on one attribute of usability: ease of learning but this connected with functionality and ease of use Will push your design in the direction of ease of use. Finds task-oriented problems Helps define users’ goals and assumptions Usable early in development process Applicable to to-day’s GUI/DM environment

7. 6 Drawbacks of CW Not ideal for highly trained users or efficiency- oriented interfaces. Nuclear power plant operators Air traffic controllers Telephone operators Assumes that users will not read the manual first Time-consuming Need knowledgeable evaluators Needs task definition methodology Applies primarily to ease of learning problems

8. 7 Readings Short introduction by authors http://www.acm.org/sigchi/chi95/Electronic/documnts/tutors /jr_bdy.htm Lewis & Reiman Book ftp://ftp.cs.colorado.edu/pub/distribs/clewis/HCI-Design- Book/ ftp://ftp.cs.colorado.edu/pub/distribs/clewis/HCI-Design- Book/ Wharton, C., Rieman, J., Lewis, C., and Polson, P. The cognitive walkthrough method: A practitioner’s guide. In J. Nielsen and R. Mack (Eds.), Usability inspection methods. John Wiley & Sons, Inc., New York, NY, 1994.