“…Because the concept is abstract and difficult to measure directly, evidence of mental models was often gleaned indirectly through participant observation and interviews. The existing research has examined characteristics of mental models, such as accuracy and completeness (Dimitroff, 1990;Zhang, 1998), their developmental phases (Katzeff, 1990), transfer of mental models between systems (Marchionini, 1986), mental models' effects on people's interaction with systems (Borgman, 1986;Muramatsu & Pratt, 2001), and factors that affect mental models'sophistication (Papastergiou, 2005;Otter & Johnson, 2000;Thatcher & Greyling, 1998). However, the fundamental questions, such as what elements constitute mental models, what relationships exist between the elements, and what forms mental models take, have received less attention in the current literature.…”