This book covers the problem of fidelity in the design of virtual environments with specific reference to the design of vehicle simulators. The default design goal has been on the physical replication of a given real-world environment and, in the case of vehicles, the specific appearance and function of vehicle components. This book discusses that perceptual, rather than physical, fidelity of a virtual environment, should be the design goal and the principal purpose is to produce human behavior. This book provides the rationale and design guidance to maximize perceptual fidelity in the development of virtual environments, and therefore maximize the costeffectiveness as well.