Handbook of Driving Simulation for Engineering, Medicine, and Psychology

Simulator and Scenario Factors Influencing Simulator Sickness

Authors
Heather A. Stoner, Realtime Technologies, Inc.
Donald L. Fisher, University of Massachusetts
Michael Mollenhauer, Jr., Virginia Tech Transportation Institute

Abstract
The Problem. The consequences and implications of simulator sickness for the validity of simulation can be severe if not controlled and taken into account (Casali, 1986). Many of today’s driving simulators are used to perform research, training, or proof of design activities. A prerequisite to generalizing the results found in research conducted in a simulator is an understanding of the validity of the resulting experience. Without question, simulator sickness is a factor that can affect the validity of research simulators. Given the potential consequences of simulator sickness, it is difficult to assess the value of the results obtained from a simulator study known to have significant sickness problems. Role of Driving Simulators. There are alternatives to driving simulators for studying most, if not all, issues. However, these alternatives are often unsafe, do not provide a well-controlled environment, and require large sums of money to implement. Thus, driving simulators are necessary and the associated issues of simulator sickness need to be addressed. Key Results of Driving Simulator Studies. Simulator sickness can affect a driver’s performance in a variety of negative ways due to inappropriate behaviors, loss of motivation, avoidance of tasks that are found disturbing, distraction from normal attention allocation processes, and a preoccupation with the fact that something is not quite right. On the positive side, simulator selection, participant screening, scenario design, and control of the environment can all reduce the incidence of simulator sickness. Scenarios and Dependent Variables. Examples of the sorts of scenarios that lead to extremes of simulator sickness are discussed. Additionally, the various measures that have been used against simulator sickness are highlighted, including some with predictive validity. Platform Specificity and Equipment Limitations. Simulator sickness appears to be most extreme in fully immersive environments and when head-mounted displays are used. A motion base does not necessarily reduce simulator sickness symptoms.

Keywords
Simulator Sickness, Vestibular System, Visual System, Vection

Key Points
• There is a difference between motion sickness and simulator sickness. While the symptoms of motion and simulator sickness overlap, there are clear differences in the causes of these two different types of sickness.
• There are several different theories of simulator sickness. These include theories that refer to inter- and intramodal sensory cue conflicts, the body’s response to position, postural instabilities, and rest-frame inconsistencies. No theory has yet explained or predicted simulator sickness completely.
• Arguably, conflicting cues from the vestibular and visual systems influence simulator sickness the most. The features of each system that are most often in conflict in a simulator are discussed.
• There are several well-validated measures of simulator sickness that could be used in almost any study where simulator sickness is expected as a problem. Because simulator sickness can affect all aspects of driving, without such measures one cannot safely generalize results from a simulator to real driving.
• There are various preventive measures for simulator sickness. These methods, such as screening participants, controlling environmental conditions, and scene and scenario design, should be used when possible to help reduce sickness.

Key Readings
Casali, J. (1986). Vehicular simulation-induced sickness, Volume I: An overview (IEOR Tech. Rep. 8501). Virginia Polytechnic Institute and State University, VA.

Kennedy, R., and Fowlkes, J. (1992). Use of a motion sickness history questionnaire for prediction of simulator sickness. Aviation, Space and Environmental Medicine, 63, 588–593.

Kennedy, R., Stanney, K., and Dunlap, W. (2000). Duration and exposure to virtual environments: Sickness curves during and across sessions. Presence: Teleoperators and Virtual Environments, 9(5), 463–472.

McCauley, M., and Sharkey, T. (1992). Cybersickness: Perception of self-motion in virtual environments. Presence: Tele-operators and Virtual Environments, 1, 311–318.

Pausch, R., Crea, T., and Conway, M. (1992). A literature survey for virtual environments: Military flight simulator visual systems and simulator sickness. Presence: Teleoperators and Virtual Environments, 1(3), 344–363.