Cognitive walkthrough
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The Cognitive walkthrough method is a usability inspection method used to identify usability issues in a piece of software or web site, focusing on how easy it is for new users to accomplish tasks with the system. The method is rooted in the notion that users typically prefer to learn a system by using it to accomplish tasks, rather than, for example, studying a manual. The method is prized for its ability to generate results quickly with low cost, especially when compared to usability testing, as well as the ability to apply the method early in the design phases, before coding has even begun.
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[edit] Introduction
A cognitive walkthrough starts with a task analysis that specifies the sequence of steps or actions required by a user to accomplish a task, and the system responses to those actions. The designers and developers of the software then walkthrough the steps as a group, asking themselves a set of questions at each step. Data is gathered during the walkthrough, and afterwards a report of potential issues is compiled. Finally the software is redesigned to address the issues identified.
The effectiveness of methods such as cognitive walkthroughs is hard to measure in applied settings, as there is very limited opportunity for controlled experiments while developing software. Typically measurements involve comparing the number of usability problems found by applying different methods. However, Gray & Salzman called into question the validity of those studies in their dramatic 1998 paper "Damaged Merchandise", demonstrating how very difficult it is to measure the effectiveness of usability inspection methods. However, the consensus in the usability community is that the cognitive walkthrough method works well in a variety of settings and applications.
[edit] Walking through the tasks
After the task analysis has been made the participants perform the walkthrough by asking themselves a set of questions for each subtask. Typically four questions are asked[1]:
- Will the user try to achieve the effect that the subtask has? Does the user understand that this subtask is needed to reach the user's goal?
- Will the user notice that the correct action is available? E.g. is the button visible?
- Will the user understand that the wanted subtask can be achieved by the action? E.g. the right button is visible but the user does not understand the text and will therefore not click on it.
- Does the user get feedback? Will the user know that they have done the right thing after performing the action?
By answering the questions for each subtask usability problems will be noticed.
[edit] History
The method was developed in the early nineties by Wharton, et al, and reached a large usability audience when it was published as a chapter in Jakob Nielsen's seminal book on usability, "Usability Inspection Methods." The Wharton, et al method required asking four questions at each step, along with extensive documentation of the analysis. In 2000 there was a resurgence in interest in the method in response to a CHI paper by Spencer who described modifications to the method to make it effective in a real software development setting. Spencer's streamlined method required asking only two questions at each step, and involved creating less documentation. Spencer's paper followed the example set by Rowley, et al who described the modifications to the method that they made based on their experience applying the methods in their 1992 CHI paper "The Cognitive Jogthrough".
[edit] References
- ^ C. Wharton et al. "The cognitive walkthrough method: a practitioner's guide" in J. Nielsen & R. Mack "Usability Inspection Methods" pp. 105-140.
[edit] Further reading
- Lewis, L. Polson, P, Wharton, C. & Rieman, J. (1990) Testing a Walkthrough Methodology for Theory-Based Design of Walk-Up-and-Use Interfaces Chi ’90 Proceedings pp235-242
- Jeffries, R. Miller, J. R. Wharton, C. Uyeda, K. M. (1991) User Interface Evaluation in the Real World: A comparison of Four Techniques Conference on Human Factors in Computing Systems pp 119 – 124
- Wharton, C. Bradford, J. Jeffries, J. Franzke, M. Applying Cognitive Walkthroughs to more Complex User Interfaces: Experiences, Issues and Recommendations CHI ’92 pp381-388
- Rowley, David E., and Rhoades, David G (1992). The Cognitive Jogthrough: A Fast-Paced User Interface Evaluation Procedure. Proceedings of CHI '92, 389-395.
- Sears, A. (1998) The Effect of Task Description Detail on Evaluator Performance with Cognitive Walkthroughs CHI 1998 pp259-260
- Gray, W. & Salzman, M. (1998). Damaged merchandise? A review of experiments that compare usability evaluation methods, Human-Computer Interaction 13, 203-61.
- Gray, W.D. & Salzman, M.C. (1998) Repairing Damaged Merchandise: A rejoinder. Human-Computer Interaction vol.13 no.3 pp325-335
- Spencer, R. (2000) The Streamlined Cognitive Walkthrough Method, Working Around Social Constraints Encountered in a Software Development Company CHI 2000 vol.2 issue 1 pp353-359
- Blackmon, M. H. Polson, P.G. Muneo, K & Lewis, C. (2002) Cognitive Walkthrough for the Web CHI 2002 vol.4 No.1 pp463-470
- Blackmon, M. H. Polson, Kitajima, M. (2003) Repairing Usability Problems Identified by the Cognitive Walkthrough for the Web CHI 2003 pp497-504
- Good, N. S. & Krekelberg, A. (2003) Usability and Privacy: a study of KaZaA P2P file-sharing CHI 2003 Vol.5 no.1 pp137-144
- Dix, A., Finlay, J., Abowd, G., D., & Beale, R. (2004). Human-computer interaction (3rd ed.). Harlow, England: Pearson Education Limited. p321
- Gabrielli, S. Mirabella, V. Kimani, S. Catarci, T. (2005) Supporting Cognitive Walkthrough with Video Data: A Mobile Learning Evaluation Study MobileHCI ’05 pp77-82
- Hornbaek, K. & Frokjaer, E. (2005) Comparing Usability Problems and Redesign Proposal as Input to Practical Systems Development CHI 2005 391-400
[edit] External links
[edit] See also
- Cognitive dimensions, a framework for identifying and evaluating elements that affect the usability of an interface.
- Comparison of usability evaluation methods
