From mental effort to perceived usability

In many cases, practitioners and researchers of Human-Computer Interaction and Usability Engineering rely on users' subjective product quality assessments. Such an assessment of, for example, perceived usability is believed to summarize previous experiences made with the according software. The present study shows that such summary assessments of perceived usability do not reflect a whole experiential episode, but rather its most recent incidents. Additional measurement strategies, such as repeated measurements of perceived usability throughout the experiential episode, are explored.