Mental models are mental representations of the external world that humans constantly use when they interact with the environment and systems within it. These mental models are in part constituted by an underlying structure of associated concepts that are modified as a person gains experience with a sys- tem or domain. Video games provide a context that encourages the development of sophisticated mental models. The current research sought to understand how mental model structures differ between video game players of varying experience levels. Participants were recruited both over internet forums and through Mechanical Turk. Mental model structures were mea- sured using relatedness ratings between pairs of con- cepts that were derived from players with high levels of experience playing League of Legends. Relatedness ratings were transformed into Pathfinder networks that were used to analyze mental model structures. Results revealed structural differences in mental mod- els between experience levels. A three-stage model of mental model structure development is proposed to explain the results, which suggest that some structural characteristics appear earlier in mental model develop- ment than others. The role of mental model structural characteristics is discussed in light of both the design of training programs and video games. Keywords: declarative memory, experience, knowl- edge organization, knowledge structure, mental models, pathfnder network, topics, training, video game People do not interact with technological artifacts; they interact with their mental models of those artifacts (e.g., Norman, 1983). Consequently, people frequently use mental models as they complete daily tasks. Simple tasks, such as driving to work, operating a computer, and cooking a meal require the use of mental models for successful completion (Gentner, 2002; Norman, 1983). Mental models are also useful when performing more complex tasks, such as air traffic control and the medical care activities by physicians and nurses (Mogford, 1997; Smith & Koppel, 2014). The pervasiveness of mental models in routine human activity, especially as it relates to inter- action with technology, reveals the importance of understanding how these models are formed, used, and adjusted over time. To further our understanding of mental models, the current research examined how the memory structures of mental models differed between people who have varying degrees of experience playing a video game. Mental Models Defining the term. The roots of the term mental model can be traced back to Kenneth Craik’s (1943) book The Nature of Explanation. Craik suggested that humans hold small-scale models of reality in their minds that are used to reason and solve problems in their environment. Later, Johnson-Laird (1983) posited that people create analogical models of aspects of the envi- ronment, which they use in deductive problem solving. Another pioneer of mental models, Norman (1983), suggested that people construct internal representations of the systems with which they interact and that these representa- tions “provide predictive and explanatory power for understanding the interaction” (p. 7). He described mental models as knowledge about objects and the environment gathered from interaction with that environment. Rouse and Morris (1986) warned that defining mental models too broadly could result in a definition that is no different from general knowledge and provides no additional theoretical or practical utility. We suggest a useful definition of mental models that avoids these concerns. First, mental 773236EDM XX X 10.1177/1555343418773236Journal of Cognitive Engineering and Decision MakingMental Models: Structure and Experience 2018 Address correspondence to Caleb S. Furlough, Department of Psychology, North Carolina State University, Raleigh, NC 27606, USA, csfurlou@ncsu.edu Mental Models: Structural Differences and the Role of Experience Caleb S. Furlough and Douglas J. Gillan, North Carolina State University Journal of Cognitive Engineering and Decision Making 201X, Volume XX, Number X, Month 2018, pp. 1–19 DOI: 10.1177/1555343418773236 Copyright © 2018, Human Factors and Ergonomics Society.