Unix system mental models and Unix system expertise

A study is described, whose purpose was to develop a model of users' knowledge of the Unix operating system and thus to depict the relationship between user expertise and mental models of the Unix system. Thirty computer science and engineering majors with varying levels of expertise participated in the experiment. Expertise was measured by experience with the Unix system and computing, as well as by self-descriptions. Mental models were examined by asking subjects to: sort Unix system terms according to their similarity and construct a graph using Unix system terms. Models of experts possess more abstract and semantically bound information than models of those less expert in the Unix system. Experts best represent the higher levels of the Unix system; novices more fully represent the lower, more concrete levels of the system. The potential utility of the experts' representation is discussed with respect to performing tasks within the Unix system.<>