To make the browsing agent mimic the behavior of a typical user, we've used some psychological modeling techniques, which we describe below. Effectively and automatically measuring and comparing aspects of typical user experience is a tall order. But humans do behave consistently in many areas. They take longer to read long paragraphs than short ones. They take longer to find a choice in a list of 50 items than in a list of 5.
Reference models are an established tool in complex forms of analysis.
Consider the crash test dummy. At WebCriteria, we set out to develop a browsing-behavior reference model that describes the process of loading a page, scanning it for desired content, selecting links, loading the next page, and so on. We use a technique known to psychologists as GOMS modeling, which was first introduced in 1983, with the publication of The Psychology of Human-Computer Interaction by Stuart Card, Thomas Moran, and Allen Newell. A GOMS model decomposes any task and its associated user responses into a set of goals, operators, methods, and selection rules. Since there may be more than one method for accomplishing the goal, selection rules are used to choose among the multiple methods.