Car sickness in real driving conditions: Effect of lateral acceleration and predictability reflected by physiological changes

With the development of autonomous vehicles, car sickness may affect increasing numbers of car occupants. Car manufacturers have a real need to understand the causes of these symptoms, which occur mainly when car occupants are not engaged in a driving task. This study is the first to evaluate, in real driving conditions, the impact of lateral acceleration level and vehicle path predictability on car sickness incidence and severity, and the potential relationship with physiological changes. 24 healthy volunteers participated as front seat passengers in a slalom session inducing lateral movements at very low frequency (0.2 Hz). They were continuously monitored via physiological recordings and provided subjective car sickness ratings (CSR) after each slalom, using a 5-point likert scale. CSR reveal that (i) the greater the lateral acceleration and (ii) the less predictable the vehicle path, the more severe the car sickness symptoms in real driving conditions. An increase in several physiological parameters is also found simultaneously with higher CSR, demonstrating activation of the sympathetic nervous system. Moreover, the linear regression applied to our data suggests that these physiological parameters can be used to indicate car sickness severity. Moreover, the linear regression applied to our data suggests that the evolution of these physiological parameters may reflect the CSR level indicated by participants.