Inspection techniques are widely used during systems design as a supplement to empirical evaluations of usability. Psychology-based inspection techniques could give important insights into how thinking shapes interaction, yet most inspection techniques do not explicitly consider users’ thinking. We present an experiment comparing two psychology-based inspection techniques, cognitive walkthrough (CW) and metaphors of human thinking (MOT). Twenty participants evaluated web sites for e-commerce while keeping diaries of insights and problems experienced with the techniques. Using MOT, participants identified 30% more usability problems and in a reference collection of problems achieved a broader coverage. Participants preferred using the metaphors, finding them broader in scope. An analysis of the diaries shows that participants find it hard to understand MOT, while CW limits the scope of their search for usability problems. Participants identified problems in many ways, not only throug...