Pair of techniques for effective interface evaluation: Cognitive walkthroughs and think-aloud evaluations

Developing effective user interfaces is an iterative process. Early evaluations tend to focus on finding severe problems that need to be fixed as early as possible. As the design evolves, attention shifts toward smaller details so less severe problems are also of interest. To succeed, it is important to apply the most effective evaluation techniques at each stage. In this paper, we explain why cognitive walkthrough and think-aloud evaluations complement each other and report the results of a study that compares these techniques for use late in the development process. Our study shows that cognitive walkthroughs find the most severe usability problems along with desirable new features and functionality, while think-aloud evaluations find all types of usability problems. This paper adds to our understanding of interface evaluation techniques and provides practical advice for developers searching for techniques that are effective throughout the development process.