Micro scenarios – A Theory-based Intervention to Alleviate Simulator Sickness for Older Drivers in Driving Simulators
Authors: Sun Chongren , Samuel Siby 
Published: June 2022

Driving continues to be the fundamental way for people to transit in North America. For older adults with physical or cognitive comorbidities, automobiles remain the most suitable method to increase mobility, independence, and quality of life. However, research shows that elderly drivers are more likely to be involved in traffic accidents. For instance, drivers over 65 are overrepresented in crashes at signalized and unsignalized four-way intersections. Driving simulator-based training interventions are a safe way for training elderly drivers, particularly on effective ways to negotiate intersections. However, driving simulators result in simulator sickness or simulation adaptation syndrome (SAS). SAS can cause nausea, disorientation, vertigo, vomiting, and sickness in humans. The adverse effects of SAS are more pronounced in older drivers over 65 compared to their younger counterparts. Studies show that the dropout rates for older drivers from simulation experiments are much higher than those for younger or middle-aged drivers. Evidence from literature largely corresponds to the Motion Cue Conflict theory by Reason and Brand. It posits that the precipitating factor for SAS is the disconnect between the participants’ visual system (in motion) and their vestibular system (stationary). Several other theories may potentially explain the occurrence of SAS, such as Poison theory, the Postural Instability theory, and the Rest-frame Theory. Treisman’s Poison theory is an evolutionary theory that identifies nausea as a natural body response to complex symptoms that resemble poisoning. Riccio and Stoffgren’s postural instability theory offers an ecology-based perspective where our action and perception systems continually attempt to maintain postural stability in our environment. According to this theory, participants get sick trying to maintain stability in a new or unfamiliar environment, such as a driving simulator. Lastly, Prothero’s rest-frame theory identifies conflicting rest-frames instead of conflicting cues as the precipitator for SAS. Across the four theories, the amount of visual flow in the simulator and the time participants spend in a simulator are the common factors potentiating SAS. To alleviate SAS, several methods and approaches have been developed and evaluated. These include galvanized vestibular stimulations, galvanic cutaneous stimulation, appropriate visual background manipulations, virtual guiding avatars, and the use of alternative sensory conditions. However, none of the above interventions have improved older driver secondary glance behavior. The current paper proposes a novel methodological approach - micro scenarios, which can effectively reduce optical flow to target older driver SAS problems, especially in scenarios involving the negotiation of left turns at intersections. Micro scenarios specifically aim to decrease the total exposure time and increase the frequency of rest breaks while striving to retain the effectiveness of the training itself. Microscenarios are driven by the Postural Instability theory and the Motion cue conflict theory. Simulator-based evaluations of micro scenarios produced very low dropout rates, and participants reported very low levels of simulator sickness compared to typical scenarios. Practitioners may use these findings to train and assess at-risk populations on driving simulators.